bluuebunny/crossref_metadata_2025 huggingface dataset:
Relationship between cerebral blood flow and the development of swelling and life-threatening herniation in acute ischemic stroke
Authors: Firlik Andrew D. , Yonas Howard , Kaufmann Anthony M. , Wechsler Lawrence R. , Jungreis Charles A. , Fukui Melanie B. , Williams Robert L.
Published: June 2009

Object. The purpose of this study was to determine whether cerebral blood flow (CBF) measurements in acute stroke could be correlated with the subsequent development of cerebral edema and life-threatening brain herniation.

Methods. Twenty patients with aggressively managed acute middle cerebral artery (MCA) territory strokes who underwent xenon-enhanced computerized tomography (Xe-CT) CBF scanning within 6 hours of onset of symptoms were retrospectively reviewed. The relationship among CBF and follow-up CT evidence of edema and clinical evidence of brain herniation during the 36 to 96 hours following stroke onset was analyzed.

Initial CT scans displayed abnormal findings in 11 patients (55%), whereas the Xe-CT CBF scans showed abnormal findings in all patients (100%). The mean CBF in the symptomatic MCA territory was 10.4 ml/100 g/minute in patients who developed severe edema compared with 19 ml/100 g/minute in patients who developed mild edema (p < 0.05). The mean CBF in the symptomatic MCA territory was 8.6 ml/100 g/minute in patients who developed clinical brain herniation compared with 18 ml/100 g/minute in those who did not (p < 0.01). The mean CBF in the symptomatic MCA territory that was 15 ml/100 g/minute or lower was significantly associated with the development of severe edema and herniation (p < 0.05).

Conclusions. Within 6 hours of acute MCA territory stroke, Xe-CT CBF measurements can be used to predict the subsequent development of severe edema and progression to clinical life-threatening brain herniation. Early knowledge of the anatomical and clinical sequelae of stroke in the acute phase may aid in the triage of such patients and alert physicians to the potential need for more aggressive medical or neurosurgical intervention.
Surgical anatomy of the juxta—dural ring area
Authors: Oikawa Susumu , Kyoshima Kazuhiko , Kobayashi Shigeaki
Published: June 2009

Object. The authors report on the surgical anatomy of the juxta—dural ring area of the internal carotid artery to add to the information available about this important structure.

Methods. Twenty sides of cadaver specimens were used in this study. The plane of the dural ring was found to incline in the posteromedial direction. Medial inclination was measured at 21.8° on average against the horizontal line in the anteroposterior view on radiographic studies. Posterior inclination was measured at 20.3° against the planum sphenoidale in the lateral projection, and the medial edge of the dural ring was located 0.4 mm above the tuberculum sellae in the same projection. The lateral edge of the dural ring was located 1.4 mm below the superior border of the anterior clinoid process. The carotid cave was situated at the medial or posteromedial aspect of the dural ring; however, two of the 20 specimens showed no cave formation. The carotid cave contained the subarachnoid space in 13 sides, the arachnoid membrane only in three sides, and the extraarachnoid space in two sides. The authors propose that the marker of the medial side of the dural ring, which is more proximal than the lateral, is the tuberculum sellae in the lateral view on radiographic studies. In the medial aspect of the dural ring the intradural space can be situated below the level of the tuberculum sellae because of the existence of the carotid cave.

Conclusions. An aneurysm arising from the medial side of the juxta—dural ring area even below the tuberculum sellae is a potential cause of subarachnoid hemorrhage.
Effects of severity of host striatal damage on the morphological development of intrastriatal transplants in a rodent model of Huntington's disease: implications for timing of surgical intervention
Authors: Watts Colin , Dunnett Stephen B.
Published: June 2009

Object. The goal of this study was to investigate the effect of the severity of host neural damage on the morphological development of intrastriatal transplants in a rodent model of Huntington's disease.

Methods. Sprague—Dawley rats were subjected to unilateral striatal lesioning induced by administration of quinolinic acid (20 nM, 40 nM, or 90 nM). Seven days postlesioning, intrastriatal cell suspension grafts were placed in the right striatum in some of these animals. Grafts were also placed in the right striatum of additional animals that had not been subjected to lesioning. The rats were killed and processed for morphological analysis 8 weeks after grafting.

The results indicate that striatal grafts survive and grow much better when implanted into a lesioned striatum rather than into an intact striatum, as measured both by the volume and the numbers of medium-sized spiny neurons within the graft. Only a small or modest lesion is necessary to produce this effect. By some measures (such as graft volume) grafts survive less well when the lesion is more extensive. The presence of a graft reduced the extent of striatal atrophy induced by the lesions, but this effect was not caused by differences in the numbers of surviving neurons per se.

Conclusions. These results have significant implications for the timing of surgical intervention and patient selection with respect to current and future clinical trials of striatal transplantation in the treatment of Huntington's disease.
Reversal of cerebral vasospasm using an intrathecally administered nitric oxide donor
Authors: Wolf Erich W. , Banerjee Amit , Soble-Smith Jill , Dohan F. Curtis , White Richard P. , Robertson James T.
Published: June 2009

Object.Intrathecal bolus administration of (Z)-1-[N-(2-aminoethyl)-N-(2-ammonioethyl)aminio]diazen-1-ium-1,2-diolate (DETA/NO), a long half-life diazeniumdiolate-class nitric oxide (NO) donor, was evaluated for safety and efficacy in the treatment of delayed cerebral vasospasm in a canine model of subarachnoid hemorrhage (SAH).

Methods.The baseline basilar artery (BA) diameter of 25 dogs was measured with the aid of angiography on Day 0. Vasospasm was then induced by intracisternal injection of autologous arterial blood on Days 0 and 2. Repeated arteriography on Day 7 revealed an average BA diameter of 58% of baseline. Each dog was then randomized to one of four groups: a pathology control group (SAH only, four animals); a treatment control group (SAH plus 2 µmol of the inactive drug carrier DETA, eight animals); a low-dose treatment group (SAH plus 0.2 µmol DETA/NO, six animals); or a high-dose treatment group (SAH plus 2 µmol DETA/NO, six animals). The drugs were administered in a 2-ml intrathecal bolus via the cisterna magna. Arterial caliber was monitored by angiography over the subsequent 4 hours. A 2-µmol dose of the drug was then given and serial arteriography continued for an additional hour to screen for tachyphylaxis. Intracranial pressure and respiratory and hemodynamic parameters were continuously monitored. Histopathological analyses of the animals' brains were performed after the dogs were killed on Day 8.

The drug DETA/NO produced reversal of vasospasm in a dose-dependent fashion that roughly followed a double exponential time course. Doses of 2 µmol DETA/NO resulted in restoration of the angiographically monitored BA diameter to the prevasospasm size at 1.5 hours posttreatment, and this was sustained at 88% of baseline at 4 hours (p < 0.01, independent samples t-test). By contrast, the treatment control group remained on average at 54% of baseline diameter. The low-dose treatment group achieved only partial and more transitory relaxation. Histopathological analyses showed findings consistent with chronic SAH but did not demonstrate any toxicity associated with the NO donor. No adverse physiological changes were seen.

Conclusions.This study indicates that long-acting NO donors are potentially useful as agents to restore circulation in patients suffering from cerebral vasospasm.
Role of tyrosine kinase in erythrocyte lysate—induced contraction in rabbit cerebral arteries
Authors: Kim Chul-Jin , Kim Kee-Won , Park Jin-Woo , Lee Jung-Chung , Zhang John H.
Published: June 2009

Object.This study was undertaken to explore whether erythrocyte lysate, a proposed cause of vasospasm, produces vasoconstriction by activation of tyrosine kinase in rabbit cerebral arteries.

Methods.Isometric tension was used to monitor contractions in rabbit basilar arteries induced by erythrocyte lysate, 5-hydroxytryptamine (5-HT), or KCl in the absence or presence of tyrosine kinase inhibitors. Erythrocyte lysate, 5-HT, or KCl produced concentration-dependent contractions in rabbit basilar arteries. Preincubation with the tyrosine kinase inhibitors tyrphostin A23 and genistein (30 and 100 µM), but not diadzein, an inactive analog of genistein, attenuated significantly the contraction induced by erythrocyte lysate (p < 0.05). Tyrphostin A23, genistein, and diadzein (30 µM) failed to reduce the contraction caused by 5-HT. Genistein, but not tyrphostin A23 or diadzein (30 µM), attenuated significantly the contraction induced by KCl (p < 0.05). In another series, arterial rings were initially contracted with erythrocyte lysate, 5-HT, or KCl and the relaxant effect of genistein was then tested. Genistein relaxed rabbit basilar arteries that had been contracted by exposure to erythrocyte lysate, 5-HT, or KCl (30–100 µM; p < 0.05).

Conclusions.These data indicate that tyrosine kinase may play a role in the regulation of cerebral arterial contraction and tyrosine kinase inhibitors may be useful in the management of cerebral vasospasm.
Acute hearing loss following fractionated stereotactic radiosurgery for acoustic neuroma
Authors: Chang Steven D. , Poen Joseph , Hancock Steven L. , Martin David P. , Adler John R.
Published: June 2009

✓ Two cases of acute hearing loss are reported following fractionated stereotactic radiosurgery for acoustic neuroma. Both patients had neurofibromatosis type 2 and were treated with a peripheral tumor dose of 21 Gy delivered in three fractions (7 Gy each) with a minimum interfraction interval of 10 hours. One patient who had previously undergone surgical resection of the treated tumor presented with only rudimentary hearing in the treated ear secondary to an abrupt decrease in hearing prior to treatment. That patient reported total loss of hearing before complete delivery of the third fraction. The second patient had moderately impaired hearing prior to treatment; however, within 10 hours after delivery of the final fraction, he lost all hearing. Both patients showed no improvement in response to glucocorticoid therapy. Possible explanations for this phenomenon are presented.
Microsurgical C-2 ganglionectomy for chronic intractable occipital pain
Authors: Lozano Andres M. , Vanderlinden Graham , Bachoo Robert , Rothbart Peter
Published: June 2009

Object. The authors evaluated the effectiveness of microsurgical C-2 ganglionectomy in 39 patients with medically refractory chronic occipital pain. In this procedure the neurons transmitting sensory inputs from the occiput are removed and, unlike peripheral nerve ablation, axonal regeneration is not possible.

Methods. The patients in this series had symptoms for 1 to 43 years. In 22 patients the occipital pain was caused by trauma; in 17 patients the pain was spontaneous. Pain relief failed in 17 patients who had undergone a previous occipital neurectomy or C-2 rhizolysis. Twenty-three patients experienced pain that was described as shocklike, electric, shooting, jabbing, stabbing, sharp, or exploding (Group I). Eight patients described their pain as dull, pounding, aching, throbbing, or pressurelike (Group II). The patients underwent unilateral or bilateral C-2 open microsurgical ganglionectomies.

The postoperative follow-up period ranged from 19 to 48 months. Nineteen patients experienced an excellent result (> 90% reduction in pain). Pain caused by trauma or that described using Group I terms responded best to ganglionectomy (80% good or excellent response). In contrast, the majority of the patients with nontraumatic pain or those described using Group II descriptors did not achieve favorable results.

Conclusions. The authors conclude that: 1) patients who suffer from chronic occipital pain after having sustained injury obtain worthwhile benefit from microsurgical C-2 ganglionectomy; 2) patients suffering from migraine, tension, and vascular headaches involving the occipital area are most often not helped by this operation; and 3) terms such as “shock,” “electric,” “shooting,” “jabbing,” and “sharp” used to describe occipital pain predict a favorable pain outcome following a C-2 ganglionectomy.
Cost—benefit value of microscopic examination of intervertebral discs
Authors: Grzybicki Dana M. , Callaghan Edward J. , Raab Stephen S.
Published: June 2009

Object. Given the virtual absence of histologically detected, clinically unsuspected disease in intervertebral disc specimens, some authors have advocated that histological examination be discontinued. However, the examination of intervertebral disc specimens remains common practice in most pathology laboratories. No cost—benefit analysis of this practice has been made; therefore, the authors' goal in this study was perform such an analysis.

Methods. Using the University of Iowa surgical pathology database, 1109 patients who had undergone a laminectomy were identified retrospectively. These cases were classified into four categories based on the patients' preoperative clinical diagnosis and final histopathological diagnosis: insignificant clinical diagnosis/insignificant pathological diagnosis (ICIP), significant clinical diagnosis/insignificant pathological diagnosis (SCIP), significant clinical diagnosis/significant pathological diagnosis (SCSP), and insignificant clinical diagnosis/significant pathological diagnosis (ICSP). A significant clinical diagnosis was defined as one other than a benign, noninfectious indication for laminectomy. A significant pathological diagnosis was a diagnosis other than degenerative changes. The cost—benefit value of performing a histological examination in cases with significant or insignificant clinical diagnoses was examined. The cases were classified as: 1068 ICIP, 17 SCIP, 21 SCSP, and three ICSP. On chart review, in all three cases of ICSP an epidural abscess was identified perioperatively and the subsequent histological diagnosis did not affect patient care. The costs per case of identifying a significant pathological diagnosis with a significant and an insignificant clinical diagnosis were $44.79 and $8811, respectively.

Conclusions. Histological examination of intervertebral disc specimens is cost beneficial only if there is a significant preoperative clinical diagnosis.
A critical appraisal of syrinx cavity shunting procedures
Authors: Batzdorf Ulrich , Klekamp Jörg , Johnson J. Patrick
Published: June 2009

Object. This study was conducted to evaluate the results of shunting procedures for syringomyelia.

Methods. In a follow-up analysis of 42 patients in whom shunts were placed in syringomyelic cavities, the authors have demonstrated that 21 (50%) developed recurrent cyst expansion indicative of shunt failure. Problems were encountered in patients with syringomyelia resulting from hindbrain herniation, spinal trauma, or inflammatory processes. A low-pressure cerebrospinal fluid state occurred in two of 18 patients; infection was also rare (one of 18 patients), but both are potentially devastating complications of shunt procedures. Shunt obstruction, the most common problem, was encountered in 18 patients; spinal cord tethering, seen in three cases, may account for situations in which the patient gradually deteriorated neurologically, despite a functioning shunt.

Conclusions. Placement of all types of shunts (subarachnoid, syringoperitoneal, and syringopleural) may be followed by significant morbidity requiring one or more additional surgical procedures.
Functional image—guided surgery of intracranial tumors located in or near the sensorimotor cortex
Authors: Schulder Michael , Maldjian Joseph A. , Liu Wen-Ching , Holodny Andrei I. , Kalnin Andrew T. , Mun In Ki , Carmel Peter W.
Published: June 2009

Object. The purpose of this study was to evaluate the efficacy of noninvasive preoperative functional imaging data used in an interactive fashion in the operating room. The authors describe a method of registering preoperative functional magnetic resonance (fMR) imaging localization of sensorimotor cortex with a frameless stereotactic surgical navigation device.

Methods. The day before surgery, patients underwent blood oxygen level—dependent fMR imaging while performing a finger-tapping motor paradigm. Immediately afterward an anatomical stereotactic MR image was acquired. Raw fMR imaging data were analyzed offline at a separate workstation, and the resulting functional maps were registered to a high-resolution anatomical scan. The fused functional—anatomical images were then downloaded onto a surgical navigation computer via an ethernet connection. At surgery, the brain was exposed in the standard fashion, and the sensorimotor cortex was identified by direct cortical stimulation, the use of somatosensory evoked potentials, or both. This localization was then compared with that predicted by the registered fMR study.

Thirteen procedures were performed in 12 patients. The mean registration error was 2.2 mm. The predicted location of motor and/or sensory cortex matched that found on intraoperative mapping in all 12 patients tested. Maximal tumor resection was accomplished in each case and no new permanent neurological deficits resulted.

Conclusions. Compared with conventional brain mapping techniques, fMR image—guided surgery may allow for smaller brain exposures, localization of the language cortex with the patient under general anesthesia, and the mapping of multiple functional sites. The scanning equipment used in this method may be more readily available than for other functional imaging techniques such as positron emission tomography or magnetoencephalography.
Effect of reduced cerebral perfusion pressure on cerebral blood flow following inhibition of nitric oxide synthesis
Authors: Rise Ingunn R. , Kirkeby Ole J.
Published: June 2009

Object. The authors tested the hypothesis in a porcine model that inhibition of nitric oxide synthesis during reduced cerebral perfusion pressure (CPP) affected the relative cerebral blood flow (CBF) and the cerebrovascular resistance.

Methods. The CPP was reduced by inducing high cerebrospinal fluid pressure and hemorrhagic hypotension. With continuous blood and intracranial pressure monitoring, relative CPP was estimated using the laser Doppler flowmetry technique in nine pigs that received 40 mg/kg nitro-l-arginine methyl ester (l-NAME) and in nine control animals. The l-NAME caused a decrease in relative CBF (p < 0.01) and increases in cerebrovascular resistance (p < 0.01), blood pressure (p < 0.05), and CPP (p < 0.001). During high intracranial pressure there were no significant differences between the treated animals and the controls. After hemorrhage, there was no significant difference between the groups initially, but 30 minutes later the cerebrovascular resistance was decreased in the control group and increased in the l-NAME group relative to baseline (p < 0.05). Combined hemorrhage and high intracranial pressure increased the difference between the two groups with regard to cerebrovascular resistance (p < 0.05).

Conclusions. These results suggest that nitric oxide synthesis inhibition affects the autoregulatory response of the cerebral circulation after cardiovascular compensation has taken place. Nitric oxide synthesis inhibition enhanced the undesirable effects of high intracranial pressure during hypovolemia.
Effect of α-adrenergic blockade on the cerebrovascular response to increased intracranial pressure after hemorrhage
Authors: Rise Ingunn R. , Kirkeby Ole J.
Published: June 2009

Object. In this study the authors tested the hypothesis that hemorrhagic hypotension and high intracranial pressure induce an increase in cerebrovascular resistance that is caused by sympathetic compensatory mechanisms and can be modified by α-adrenergic blockade.

Methods. Continuous measurements of cerebral blood flow were obtained using laser Doppler microprobes placed in the cerebral cortex in anesthetized pigs during induced hemorrhagic hypotension and high cerebrospinal fluid pressure. Eight pigs received 2 mg/kg phentolamine in 10 ml saline, and 13 pigs served as control animals. During high intracranial pressure occurring after blood loss, cerebral perfusion pressure (CPP) (p < 0.01) and cerebral blood flow (p < 0.01) decreased in both groups. Cerebrovascular resistance increased (p < 0.05) in the control group and decreased < 0.005) in the phentolamine-treated group. The cerebrovascular resistance was significantly lower in the phentolamine-treated group (p < 0.05) than in the control group. Cerebrovascular resistance increased at lower CPPs in the control group (linear correlation, r = 0.39, p < 0.01) and decreased with decreasing CPP in the phentolamine-treated group (linear correlation, r = 0.76, p < 0.001).

Conclusions. This study shows that the deleterious effects on cerebral hemodynamics induced by blood loss in combination with high intracranial pressure are inhibited by α-adrenergic blockade. This suggests that these responses are caused by α-adrenergically mediated cerebral vasoconstriction.
Intracranial hypotension presenting with severe encephalopathy
Authors: Beck Carter E. , Rizk Norman W. , Kiger Lydia T. , Spencer David , Hill Laureen , Adler John R.
Published: June 2009

✓ A patient with severe and protracted symptoms from intracranial hypotension is described. The patient's presentation was marked by diffuse encephalopathy and profound depression of consciousness. This case report expands the presently known clinical spectrum of this uncommon and generally benign illness. The clinical and laboratory findings typically observed in the syndrome of intracranial hypotension are outlined. The pathophysiological mechanisms of the phenomenon are briefly discussed. Intracranial hypotension is a potentially severe illness with specific treatments that are distinct from the treatment of most neurological diseases. Three cardinal features—postural headache, pachymeningitis, and descent of midline cerebral structures—should prompt the diagnosis.
Rupture of a previously documented small asymptomatic intracranial aneurysm in a patient with autosomal dominant polycystic kidney disease
Authors: Schievink Wouter I. , Prendergast Virginia , Zabramski Joseph M.
Published: June 2009

✓ Intracranial aneurysms are common extrarenal manifestations of autosomal dominant polycystic kidney disease (ADPKD). Although their natural history is not completely understood, small asymptomatic intracranial aneurysms in patients with ADPKD often are not treated but are followed with serial magnetic resonance (MR) angiography. The authors report the unique case of a patient with ADPKD who bled from a previously documented asymptomatic 3-mm intracranial aneurysm.

This 42-year-old man with ADPKD suffered a subarachnoid hemorrhage (SAH) from a 7-mm left pericallosal artery aneurysm. This aneurysm was clipped and the patient made an excellent recovery. An irregular asymptomatic 3-mm right middle cerebral artery (MCA) aneurysm had also been demonstrated on angiography. While the patient was considering elective surgery for the MCA aneurysm, he suffered a hemorrhage from this lesion 10 weeks after the initial SAH. The aneurysm was clipped and the patient made a satisfactory recovery (he was moderately disabled).

In this report the authors indicate that small asymptomatic intracranial aneurysms are not always innocuous in patients with ADPKD, and they suggest that treatment should be strongly considered for these lesions in this group of patients when there is a history of SAH or the aneurysm is irregular in appearance. Because MR angiography studies may not adequately define the configuration of small aneurysms and irregularity may easily be missed, conventional angiography is recommended for patients with ADPKD who are found to have an intracranial aneurysm on screening with MR angiography.
Factors affecting excitatory amino acid release following severe human head injury
Authors: Bullock Ross , Zauner Alois , Woodward John J. , Myseros John , Choi Sung C. , Ward John D. , Marmarou Anthony , Young Harold F.
Published: June 2009

Object. Recent animal studies demonstrate that excitatory amino acids (EAAs) play a major role in neuronal damage after brain trauma and ischemia. However, the role of EAAs in patients who have suffered severe head injury is not understood. Excess quantities of glutamate in the extracellular space may lead to uncontrolled shifts of sodium, potassium, and calcium, disrupting ionic homeostasis, which may lead to severe cell swelling and cell death. The authors evaluated the role of EEAs in human traumatic brain injury.

Methods. In 80 consecutive severely head injured patients, a microdialysis probe was placed into the gray matter along with a ventriculostomy catheter or an intracranial pressure (ICP) monitor for 4 days. Levels of EAAs and structural amino acids were analyzed using high-performance liquid chromatography. Multifactorial analysis of the amino acid pattern was performed and its correlations with clinical parameters and outcome were tested. The levels of EAAs were increased up to 50 times normal in 30% of the patients and were significantly correlated to levels of structural amino acids both in each patient and across the whole group (p < 0.01). Secondary ischemic brain injury and focal contusions were most strongly associated with high EAA levels (27 ± 22 µmol/L). Sustained high ICP and poor outcome were significantly correlated to high levels of EAAs (glutamate > 20 µmol/L; p < 0.01).

Conclusions. The release of EAAs is closely linked to the release of structural amino acids and may thus reflect nonspecific development of membrane micropores, rather than presynaptic neuronal vesicular exocytosis. The magnitude of EAA release in patients with focal contusions and ischemic events may be sufficient to exacerbate neuronal damage, and these patients may be the best candidates for treatment with glutamate antagonists in the future.
Early changes in middle cerebral artery blood flow velocity after head injury
Authors: McQuire Joanne C. , Sutcliffe John C. , Coats Tim J.
Published: June 2009

Object. This study was designed to investigate the incidence of early abnormalities in the cerebral circulation after head injury by relating the results of the initial computerized tomography (CT) scan with transcranial Doppler (TCD) ultrasound readings to see if the side of injury and the outcome can be predicted by using these modalities.

Methods. Transcranial Doppler ultrasound measurements were obtained in the emergency room in 22 head-injured patients less than 3 hours after injury. The middle cerebral artery (MCA) was insonated using a standard technique. The TCD measurements in each MCA were examined individually; of 39 measurements, 22 (56%) showed a low mean blood flow velocity, 27 (69%) demonstrated a high pulsatility index (PI), and 18 (46%) showed both abnormalities. The side of the cerebrovascular abnormality measured by TCD ultrasound did not appear to be an accurate predictor of the side of the injury as determined on the initial CT scan. Of 13 patients in whom either a space-occupying hematoma or signs of swelling were shown on the initial CT scan, 10 (77%) had an increased PI in one or both MCAs, which is an indication of high flow resistance.

Conclusions. Transcranial Doppler ultrasound examinations performed while patients are in the emergency room may have a role in determining treatment priorities, especially in those with multiple injuries.
Cerebral monitoring by means of oximetry and somatosensory evoked potentials during carotid endarterectomy
Authors: Cho Hun , Nemoto Edwin M. , Yonas Howard , Balzer Jeffrey , Sclabassi Robert J.
Published: June 2009

Object. Cerebral ischemia that occurs during carotid endarterectomy is commonly monitored by means of somatosensory evoked potentials (SSEPs) and electroencephalography (EEG). The authors conducted this study to determine whether cerebral ischemia could also be reliably detected by cerebral oximetry.

Methods. Twenty-nine patients who underwent carotid endarterectomy were monitored by means of SSEPs, EEG, and cerebral oximetry with a model NIRO500 (20 patients) or INVOS3100A (nine patients) oximeter. Changes in amplitude of SSEPs were graded as follows: 0, no change; 1, decrease of less than 50%; 2, decrease of greater than 50%; and 3, 100% decrease. As measured with the NIRO500 oximeter, closing the common caro-tid artery decreased mean oxyhemoglobin levels twice as much (p < 0.005) in the group with SSEPs of 1 to 3 (−13.11 ± 5.59 µM [mean ± standard deviation], 12 patients) as in the group with SSEPs of 0 (−6.22 ± 5.59 µM, eight patients). The rise in deoxyhemoglobin was also greater (p < 0.05). Two of nine patients monitored with the INVOS3100A oximeter had SSEPs of 1 and 3, and their regional saturation of oxygen (rSO2) values fell by −11.50 and −11.51, respectively. In the remaining seven patients with SSEPs of 0, the rSO2 ranged between −2.00 and −6.10 with no overlap with the group with SSEPs of 1 to 3. The increase in oxyhemoglobin monitored using the NIRO500 oximeter and rSO2 monitored using the INVOS3100A machine after opening the external carotid artery was less than that seen after opening the internal carotid artery. Both types of oximeters could detect cerebral ischemia but whereas false negatives occurred with the NIRO500, none was observed with the INVOS3100A. Extracranial contamination was also four times less frequent with the INVOS3100A than with the NIRO500 monitor.

Conclusions. The results indicate that at least as measured with the INVOS3100A instrument, a decrease in rSO2 of −10 or more or a decrease below an rSO2 of 50 is indicative of cerebral ischemia of sufficient severity to decrease the amplitude of SSEPs.
Metastatic brain tumors with dural extension
Authors: Rumana Christopher S. , Hess Kenneth R. , Shi Wei Ming , Sawaya Raymond
Published: June 2009

Object.Twenty-two patients who had solitary metastatic brain tumors with dural extension were treated surgically over a 3-year period. Their cases were reviewed to characterize these lesions and to compare the patients with a similar cohort in which there was no dural involvement.

Methods.The median age of the patients was 58 years (range 11–68 years) and the male/female ratio was 12:10. The median preoperative Karnofsky Performance Scale (KPS) score in the group was 90 (range 70–100). The most common histological diagnoses seen in these patients included breast cancer, adenocarcinoma and squamous cell carcinoma of the lung, and renal cell carcinoma. All patients underwent gross-total resection of the tumor and 86% received radiation therapy. The median patient survival time was 11 months, with a median time to recurrent intracranial disease of 19 months. Survival was related to the histological diagnosis. Recurrent disease occurred in 41% of cases. Leptomeningeal disease occurred in three patients (14%). The frequency and time course of development of recurrent disease was not affected by dural resection nor was survival.

These results for patients having metastatic brain tumors with dural extension were compared with those for a cohort of 26 patients in which there were similar histological diagnosis, age, gender, and preoperative KPS score were distributed similarly but in which each patient had a single subcortical metastatic lesion. Those patients had a median survival of 10 months and the median time to recurrence was not reached. Leptomeningeal disease occurred in one patient (4%).

Conclusions.To the authors' knowledge, this is the first reported series of patients with metastatic brain tumors with dural extension. Patients with this disease may be more likely to develop recurrences along the dura and leptomeningeal disease, but the overall survival time in these patients is not different from those patients with intraparenchymal lesions.
Changing central nervous system control following intercostal nerve transfer
Authors: Malessy Martijn J. A. , Thomeer Ralph T. W. M. , Dijk J. Gert van
Published: June 2009

Object.The goal of this study was to find which central nervous system (CNS) pathways are involved in volitional control over reinnervated biceps or pectoral muscles.

Methods.Intercostal nerves (ICNs) were coapted to the musculocutaneous nerve (MCN) or the medial pectoral nerve (MPN) in 23 patients with root avulsions of the brachial plexus to restore biceps or pectoral muscle function. The facilitatory effects of respiration and voluntary contraction on cortical motor-evoked potentials of biceps or pectoral muscles were used to study CNS control over the reinnervated muscles. The time course of the facilitatory effect of respiration and voluntary contraction differed significantly. In the end stage of nerve regeneration, the facilitatory effect of voluntary contraction was significantly larger than that of respiration, indicating that the CNS control network over the muscle comes to resemble that of the recipient nerve (MCN or MPN) rather than that of the donor nerve (ICN).

Conclusions.The strengthening of previously subthreshold synaptic connections in a CNS network connecting ICN to MCN or MPN neurons may underlie changing excitability.
Fatal cyst formation after fetal mesencephalic allograft transplant for Parkinson's disease
Authors: Mamelak Adam N. , Eggerding Faye A. , Oh Daniel S. , Wilson Erika , Davis Richard L. , Spitzer Richard , Hay Jefferey A. , Caton William L.
Published: June 2009

Object. In recent years, fetal mesencephalic tissue transplant for the treatment of Parkinson's disease (PD) has been demonstrated to hold promise, but potential complications related to growth of allograft tissue have not been well described. This report explores the development and possible causation of a fatal cyst arising from a fetal transplant in the brain.

Methods. The authors report the case of a 52-year-old woman who underwent bilateral putamenal fetal mesencephalic allograft transplant for PD at another hospital. Twenty-three months later she presented to the authors' institution in a coma. Admission computerized tomography and magnetic resonance (MR) studies revealed a contrast-enhancing mural nodule and associated large cyst arising from the left putamen and causing brainstem compression. Despite surgical decompression of the cyst, the patient did not regain consciousness. Biopsy and autopsy specimens were obtained, along with an analysis of the cyst fluid. Genotyping of the nodule and the patient's peripheral lymphocytes by using polymerase chain reaction—based microsatellite analysis was also performed. Biopsy samples and autopsy histopathological studies showed inflammatory cells, hemosiderin-laden macrophages, and astrocytosis. Scattered neurons and multiple rests of choroid plexus were also noted. The cyst had a thin wall and contained liquid that was identical in composition to cerebrospinal fluid (CSF). Genotyping demonstrated the presence of alleles in the nodule DNA that were not present in lymphocytic DNA, indicating that the nodule contained allograft tissue.

Conclusions. The authors hypothesize that the choroid plexus tissue contained in the allograft resulted in CSF production and cyst formation at the transplant site, ultimately leading to the patient's herniation syndrome. The clinical history and large size of the mural nodule indicate slow growth of this allograft site and cyst over time. This case demonstrates that unusual patterns of tissue growth can occur in the brain after fetal tissue transplant and emphasizes the need for long-term monitoring of posttransplant patients by means of MR imaging. Cell sorting should be considered to ensure transplant of pure neuronal and astroglial populations.
The importance of accurate lesion placement in posteroventral pallidotomy
Authors: Eskandar Emad N. , Cosgrove G. Rees , Shinobu Leslie A. , Penney John B.
Published: June 2009

✓ Pallidotomy has become a widely used treatment for medically refractory Parkinson's disease. However, the optimal lesion size and location within the pallidum have not yet been determined, and the role of repeated pallidotomy remains undefined. The authors present two patients who had unsatisfactory results after their first unilateral pallidotomy but attained dramatic and long-lasting improvement with repeated surgery. The results obtained in these cases indicate that patients who have a good clinical outcome initially but relapse rapidly after surgery should be considered for repeated pallidotomy if the initial lesion was not placed in the optimal location.
Primary cervical melanoma with brain metastases
Authors: Salpietro Francesco M. , Alafaci Concetta , Gervasio Olga , La Rosa Giovanni , Baio Ambrogia , Cavallini Francolini Dario , Batolo Dario , Tomasello Francesco
Published: June 2009

✓ Primary intramedullary melanoma is a very rare tumor that occurs most frequently in the middle or lower thoracic spinal cord. The authors present a case of primary cervical cord melanoma that developed in a 62-year-old man who was surgically treated and subsequently underwent radiation therapy. Clinical and histogenetic features of this neoplasm and results of chemo-, radio-, and immunotherapy are reported. Both “dysembryogenetic” and “mesodermal” hypotheses on the origin of primary spinal melanoma are discussed.
Early magnetic resonance imaging of brainstem lesions after severe head injury
Authors: Firsching Raimund , Woischneck Dieter , Diedrich Michael , Klein Susan , Rückert Andreas , Wittig Holger , Döhring Wilfried
Published: June 2009

Object. The availability of magnetic resonance (MR) imaging data obtained in comatose patients after head injury is scarce, because MR imaging is somewhat cumbersome to perform in patients requiring ventilation and because, in the first hours after injury, its relevance is clearly inferior to computerized tomography (CT) scanning. The authors assessed the value of MR imaging in the early postinjury period.

Methods. In this prospective study MR imaging was performed in 61 consecutive patients within 7 days after they suffered a severe head injury. An initial CT scan had already been obtained. To understand the clinical significance of the lesions whose morphological appearance was identified with MR imaging, brainstem function was assessed by registration of somatosensory and auditory evoked potentials.

Brainstem lesions were visualized in 39 patients (64%). Bilateral pontine lesions proved to be 100% fatal and nonbrainstem lesions carried a mortality rate of 9%.

In singular cases circumstances allowed for a clear clinical distinction between primary and secondary brainstem lesions. On MR imaging all lesions were hyper- and hypointense after intervals longer than 2 days. Within shorter intervals (< 2 days) after the injury, primary lesions appeared isointense on MR imaging. In one secondary brainstem lesion there were no traces of blood.

Conclusions. Because mean intracranial pressure (ICP) levels in patients without brainstem lesions were similar to those in patients with brainstem lesions, the authors conclude that it was not mainly increased ICP that accounted for the high mortality rates in patients with brainstem lesions.

The authors also conclude that brainstem lesions are more frequently found in severe head injury than previously reported in studies based on neuropathological or CT scanning data. Early MR imaging after head injury has a higher predictive value than CT scanning.
Efficiency and safety of bilateral contemporaneous pallidal stimulation (deep brain stimulation) in levodopa-responsive patients with Parkinson's disease with severe motor fluctuations: a 2-year follow-up review
Authors: Ghika Joseph , Villemure Jean-Guy , Fankhauser Heinz , Favre Jacques , Assal Gil , Ghika-Schmid Florence
Published: June 2009

Object. The aim of this study was to evaluate the long-term safety and efficacy of bilateral contemporaneous deep brain stimulation (DBS) in patients who have levodopa-responsive parkinsonism with untreatable motor fluctuations. Bilateral pallidotomy carries a high risk of corticobulbar and cognitive dysfunction. Deep brain stimulation offers new alternatives with major advantages such as reversibility of effects, minimal permanent lesions, and adaptability to individual needs, changes in medication, side effects, and evolution of the disease.

Methods. Patients in whom levodopa-responsive parkinsonism with untreatable severe motor fluctuations has been clinically diagnosed underwent bilateral pallidal magnetic resonance image—guided electrode implantation while receiving a local anesthetic. Pre- and postoperative evaluations at 3-month intervals included Unified Parkinson's Disease Rating Scale (UPDRS) scoring, Hoehn and Yahr staging, 24-hour self-assessments, and neuropsychological examinations.

Six patients with a mean age of 55 years (mean 42–67 years), a mean duration of disease of 15.5 years (range 12–21 years), a mean “on/off” Hoehn and Yahr stage score of 3/4.2 (range 3–5), and a mean “off” time of 40% (range 20–50%) underwent bilateral contemporaneous pallidal DBS, with a minimum follow-up period lasting 24 months (range 24–30 months). The mean dose of levodopa in these patients could not be changed significantly after the procedure and pergolide was added after 12 months in five patients because of recurring fluctuations despite adjustments in stimulation parameters. All but two patients had no fluctuations until 9 months. Two of the patients reported barely perceptible fluctuations at 12 months and two at 15 months; however, two patients remain without fluctuations at 2 years. The mean improvements in the UPDRS motor score in the off time and the activities of daily living (ADL) score were more than 50%; the mean off time decreased from 40 to 10%, and the mean dyskinesia and complication of treatment scores were reduced to one-third until pergolide was introduced at 12 months. No significant improvement in “on” scores was observed. A slight worsening after 1 year was observed and three patients developed levodopa- and stimulation-resistant gait ignition failure and minimal fluctuations at 1 year. Side effects, which were controlled by modulation of stimulation, included dysarthria, dystonia, and confusion.

Conclusions. Bilateral pallidal DBS is safe and efficient in patients who have levodopa-responsive parkinsonism with severe fluctuations. Major improvements in motor score, ADL score, and off time persisted beyond 2 years after the operation, but signs of decreased efficacy started to be seen after 12 months.
Patterns of lateral sensory cortical activation determined using functional magnetic resonance imaging
Authors: Hodge Charles J. , Huckins Sean C. , Szeverenyi Nikolaus M. , Fonte Michael M. , Dubroff Jacob G. , Davuluri Krishna
Published: June 2009

Object. Functional magnetic resonance (fMR) imaging was performed in human volunteers to determine the lateral perisylvian cortical areas activated by innocuous cutaneous stimulation.

Methods. Eight volunteers who underwent 53 separate experiments form the basis of this report. Eight contiguous coronal slices were obtained using echoplanar fMR imaging techniques while participants were at rest and while somatosensory activation stimuli consisting of vibration or air puffs were delivered to various body areas. The data were analyzed using Student's t-test and cluster analysis to determine significant differences between the resting and activated states. The findings were as follows: the areas in the lateral cortex activated by the sitmuli were the primary sensory cortex (SI), the second somatosensory area (SII), the insula, the superior parietal lobule, and the retroinsular parietal operculum (RIPO). Somatotopy was demonstrable in SI but not in the other areas identified. There was a surprisingly low correlation between the amount of cortex activated in the various areas, which could mean separate inputs and functions for the areas identified. The highest correlation was found between activity in SII and RIPO (0.69).

Conclusions. The authors maintain that fMR imaging can be used to identify multiple lateral somatosensory areas in humans. Somatotopy is demonstrated in SI but not in the other lateral cortical sensory areas. The correlations between the amounts of cortex activated in the different lateral sensory areas are low. Recognition of the multiple lateral sensory areas is important both for understanding sensory cortical function and for safe interpretation of studies designed to identify the central sulcus by activating SI.
Functional evaluation using magnetic resonance imaging of the visual cortex in patients with retrochiasmatic lesions
Authors: Kollias Spyros S. , Landau Klara , Khan Nadia , Golay Xavier , Bernays Rene , Yonekawa Yasuhiro , Valavanis Anton
Published: June 2009

Object. The goal of this study was to evaluate the clinical potential of combining functional magnetic resonance (fMR) imaging with conventional morphological MR imaging and to assess its usefulness for objective evaluation of visual function as part of treatment planning in patients harboring space-occupying lesions involving the posterior afferent visual system.

Methods. It was hypothesized that regional activation of the visual cortex during visual stimulation would show an asymmetric response consistent with the well-known retinotopical organization of the human visual cortex. To test this hypothesis, the pattern of regional cortical activity detected by fMR imaging during binocular repetitive photic stimulation (10 Hz) was compared with the findings of conventional visual field testing. Functional mapping of the visual cortex was performed using a noninvasive blood oxygen level—dependent MR technique in 10 patients with intraaxial and two with extraaxial lesions. Experiments involving two of the patients were unsuccessful because of motion artifacts. In all the remaining patients functional activity was demonstrated in the primary visual area that corresponded to the anatomical location of the calcarine cortex. In nine patients, the identified patterns of activation in the visual cortex were consistent with the visual field deficits (seven homonymous hemianopsias, one homonymous central scotoma, and one inferior quadrantanopsia) and with the traditional teaching of retinotopical representation. Discordance between fMR imaging and perimetric findings was observed in one case.

Conclusions. These results demonstrate that fMR imaging can be performed routinely and successfully in patients with visual abnormalities as part of a conventional neuroradiological evaluation. The technique provides essential information about the function—structure relationship specific to an individual patient and holds promise not only for diagnosis and therapy planning, but also for understanding the topography and functional specialization of the human visual cortex.