bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chronic motor cortex stimulation in patients with thalamic pain
Authors: Tsubokawa Takashi , Katayama Yoichi , Yamamoto Takamitsu , Hirayama Teruyasu , Koyama Seigou 
Published: May 2009

✓ Analysis of the authors' experience over the last 10 years has indicated that excellent pain control has rarely been obtained by thalamic relay nucleus stimulation in patients with thalamic pain. In the present study, 11 patients with thalamic pain were treated by chronic stimulation of the precentral gyrus. In eight patients (73%), the stimulation system was internalized since excellent pain control was achieved during a 1-week test period of precentral gyrus stimulation. In contrast, no clear effect was noted or the original pain was even exacerbated by postcentral gyrus stimulation. The effect of precentral stimulation was unchanged in five patients (45%) for follow-up periods of more than 2 years. In the remaining three patients, the effect decreased gradually over several months. This outcome was significantly better than that obtained in an earlier series tested by the authors with thalamic relay nucleus stimulation (p < 0.05). The pain inhibition usually occurred at intensities below the threshold for production of muscle contraction (pulse duration 0.1 to 0.5 msec, intensity 3 to 8 V). When good pain inhibition was achieved, the patients reported a slight tingling or mild vibration sensation during stimulation projected in the same area of distribution as their pain.
The authors discuss the possibility that, in deafferentation pain, sensory neurons below the level of deafferentation cannot exert their normal inhibitory influences toward deafferented nociceptive neurons because of the development of aberrant connections. Thus, while stimulation of the first- to third-order sensory neurons at the level of the thalamic relay nucleus or below cannot bring about good pain inhibition in patients with thalamic pain, activation of hypothetical fourth-order sensory neurons through precentral stimulation may be able to inhibit deafferented nociceptive neurons within the cortex. None of the patients developed either observable or electroencephalographic seizure activity.
Use of the excimer laser in high-flow bypass surgery of the brain
Authors: Tulleken Cornelis A. F. , Verdaasdonk Ruud M. , Berendsen Wim , Mali W. P. T. M. 
Published: May 2009

✓ The technique of laser-assisted anastomosis for high-flow bypass surgery using the excimer laser is described in 15 rabbits and in one patient. The left common carotid artery of the rabbits was excised and, with two anastomoses, connected to the right common carotid artery. An end-to-side anastomosis technique was used that obviated the temporary occlusion of the recipient artery. The end of the donor artery was connected for its full circumference with the exterior of the recipient artery and, with the aid of an excimer laser catheter (introduced via an artificial side branch of the donor artery), the wall of the recipient artery was evaporated. In two animals only, occlusion of the anastomosis sites occurred. In the remaining 13 animals both anastomosis sites were proven to be patent by inspection at different times, followed by scanning electron microscopy in six animals.
In a patient with hypoperfusion of the brain caused by bilateral internal carotid artery occlusion, revascularization of the right hemisphere was obtained by placing a shunt between the proximal superficial temporal artery and the intracranial portion of the internal carotid artery, using a free transplant of the right inferior epigastric artery. The anastomosis with the internal carotid artery was created using the excimer laser-assisted technique without occlusion of the recipient artery.
Intraoperative localization using an armless, frameless stereotactic wand
Authors: Barnett Gene H. , Kormos Donald W. , Steiner Charles P. , Weisenberger Joe 
Published: May 2009

✓ A technique of “frameless” stereotaxy that allows real-time intraoperative neurosurgical localization is described. The system is composed of four components: a hand-held probe containing two ultrasonic emitters, a microphone array that is rigidly affixed to the operating table in proximity to the surgical field, hardware to control and detect timing of signal production and reception, and a color graphics computer workstation with software to calculate and present the location of the probe tip on reconstructed neuroimaging studies. Unlike previously reported mechanical or sonic navigational devices, this system is adaptable to a wide array of neurosurgical instruments, allows free movement of the operating table and conventional patient draping, and has accuracy in the hostile operating room environment that rivals that of frame stereotaxy.
In the operating room environment, using four pulse pairs with the wand positioned optimally, reproducibility of a point in space is ± 0.6 mm. The wand has a broad range of orientations that maintain error at or below 1.0 mm. The mean error when measuring distances within a 1000-cu cm cube is 1.1 ± 1.0 mm (1.0% ± 0.7%). The ability to localize a fourth point (a target) in space is typically within 1.5 mm (using computerized tomography scans with a 1-mm slice thickness) but is dependent on several variables. This technology provides a powerful yet flexible tool in the neurosurgical operating room.
Tonsillar herniation: the rule rather than the exception after lumboperitoneal shunting in the pediatric population
Authors: Chumas Paul D. , Armstrong Derek C. , Drake James M. , Kulkarni Abhaya V. , Hoffman Harold J. , Humphreys Robin P. , Rutka James T. , Hendrick E. Bruce 
Published: May 2009

✓ Although the development of tonsillar herniation (acquired Chiari malformation) in association with lumboperitoneal (LP) shunting is well recognized, it has previously been considered rare. In order to ascertain the incidence of this complication after LP shunting, the authors undertook a retrospective study of all patients in whom this form of shunt had been inserted between 1974 and 1991 at The Hospital for Sick Children, Toronto. In the 143 patients, the mean age at insertion was 3.3 years and the indications for shunt placement were hydrocephalus (81%), pseudotumor cerebri (7%), cerebrospinal fluid fistula (6%), and posterior fossa pseudomeningocele (6%). The mean follow-up period was 5.7 years, during which time there was one shunt-related death due to unsuspected tonsillar herniation. Five other patients developed symptomatic tonsillar herniation treated by suboccipital decompression.
Review of all computerized tomography (CT) scans not degraded by artifact showed evidence of excess soft tissue at the level of the foramen magnum in 38 (70%) of 54 patients so studied. In order to confirm that this CT finding represented hindbrain herniation, sagittal and axial magnetic resonance (MR) images were obtained for 17 asymptomatic patients and revealed tonsillar herniation (range 2 to 21 mm) in 12 (70.6%). In addition, some of these asymptomatic patients had evidence of uncal herniation and mesencephalic distortion. Similarities and distinctions are drawn between the morphological changes occurring after LP shunting and those seen in association with the Chiari I and II malformations. Although less than 5% of this study population required treatment for tonsillar herniation, the incidence of this complication was high in asymptomatic patients; MR imaging surveillance for patients with LP shunts is therefore recommended.
Progressive myelopathy secondary to odontoid fractures: clinical, radiological, and surgical features
Authors: Crockard H. Alan , Heilman Alan E. , Stevens John M. 
Published: May 2009

✓ Late-onset progressive myelopathy, years after odontoid fracture, is considered a rarity. Sixteen patients with diagnosis of their odontoid fractures delayed from four months to 45 years have been studied and treated. Three had forgotten about the injury and, in the rest, the significance had been minimized by their clinicians. Fifteen patients had characteristic C-2 nerve root pain and 10 had noted weak hands and walking difficulties. Fifteen patients had Type II fractures, which were mobile in 11; hypertrophic pseudarthrosis was marked in two. In seven patients it was confirmed at surgery that all or part of the transverse ligament was interposed in the fracture. Transoral surgery, combined with a variety of posterior fusion techniques, has allowed cord decompression, an understanding of the pathomechanics, and sound posterior bone fusion with arrest of the myelopathic condition.
Measurements of craniovertebral angles and cord cross-sectional area in this series revealed a rough correlation, but the most striking relationship was between length of delay in diagnosis and diminished cord area in both non-union and malunion, suggesting a progressive injury mechanism. It is proposed that late myelopathy following odontoid fracture may be more common than hitherto believed and should be considered in the evaluation of patients with cervical spondylosis. The condition may be progressive. Finally, non-union may be due to interposition of the transverse ligament.
The radiobiology of human acoustic schwannoma xenografts after stereotactic radiosurgery evaluated in the subrenal capsule of athymic mice
Authors: Linskey Mark E. , Martinez A. Julio , Kondziolka Douglas , Flickinger John C. , Maitz Ann H. , Whiteside Theresa , Lunsford L. Dade 
Published: May 2009

✓ An experimental model with xenograft transplantation into the subrenal capsule of athymic (nude) mice was used to evaluate the early response of human acoustic schwannomas to stereotactic radiosurgery. After xenograft placement, 45 mice underwent radiosurgery with single doses of 10, 20, or 40 Gy using a 201-source 60Co gamma unit (4-mm collimator, single isocenter, 80% isodose line). The 45 radiosurgery-treated xenografts were compared with 15 untreated xenografts and 15 xenografts in mice that underwent “sham radiosurgery.” All five study groups were matched for the following pretreatment variables: patient of origin, animal weight, average xenograft diameter, and percentage of xenograft surface vascularity. Immediately prior to sacrifice of the mice all xenografts were evaluated in situ to determine the average tumor diameter, tumor volume, and percentage of surface vascularity. Mice were sacrificed 2 weeks, 1 month, or 3 months after radiosurgery. Blinded histological review was performed by an independent neuropathologist.
Tumor volume was reduced 33.6% after 2 weeks (p = 0.023) and 45% after 3 months (p = 0.018) in the 40-Gy radiosurgery group. Tumor volume was reduced by 46.2% after 1 month (p = 0.0002) and 35.2% after 3 months (p = 0.032) in the 20-Gy radiosurgery group. An average volume reduction of 16.4% was observed after 3 months (p = 0.17) in the 10-Gy radiosurgery group. At 3 months after surgery, tumor surface vascularity was reduced by an average of 19.7% (p = 0.043) in the 40-Gy radiosurgery group and 5.8% (p = 0.12) in the 20-Gy radiosurgery group and was unchanged in the 10-Gy radiosurgery group and both control groups. Histological examination demonstrated a higher incidence of hemosiderin deposits (p = 0.026) and vascular mural hyalinization (p = 0.032) in radiosurgery xenografts versus control.
The subrenal capsule xenograft in nude mice was an excellent model for studying the in vivo radiobiology of acoustic schwannomas after radiosurgery. Both cellular and vascular effects could be assessed serially in situ and the model was stable even 4 months after transplantation. Additional studies investigating radiobiology over periods better approximating the time course of clinical neuroimaging changes (6 to 12 months) are warranted.
The surgical treatment of painful traumatic neuromas
Authors: Burchiel Kim J. , Johans Timothy J. , Ochoa Jose 
Published: May 2009

✓ Pain following suspected nerve injury was comprehensively evaluated with detailed examination including history', neurological evaluation, electrodiagnostic studies, quantitative sensory testing, thermography, anesthetic agents, and sympathetic nerve blocks. Forty-two surgically treated patients fell into four discrete groups: Group 1 patients had distal sensory neuromas treated by excision of the neuroma and reimplantation of the proximal nerve into muscle or bone marrow; Group 2 patients had suspected distal sensory neuromas in which the involved nerve was sectioned proximal to the injury site and reimplanted; Group 3 patients had proximal in-continuity neuromas of major sensorimotor nerves treated by external neurolysis; and Group 4 patients had proximal major sensorimotor nerve injuries at points of anatomical entrapment treated by external neurolysis and transposition, if possible. Patient follow-up monitoring from 2 to 32 months (average 11 months) was possible in 40 (95%) of 42 patients. Surgical success was defined as 50% or greater improvement in pain using the Visual Analog Scale or pain relief subjectively rated as either good or excellent, without postoperative narcotic usage. Overall, 16 (40%) of 40 patients met those criteria. Success rates varied as follows: 44% in 18 Group 1 patients, 40% in 10 Group 2 patients, 0% in five Group 3 patients, and 57% in seven Group 4 patients. Twelve (30%) of 40 patients were employed both pre- and postoperatively.
It is concluded that: 1) neuroma excision, neurectomy, and nerve release for injury-related pain of peripheral nerve origin yield substantial subjective improvement in a minority of patients; 2) external neurolysis of proximal mixed nerves is ineffective in relieving pain; 3) surgically proving the existence of a neuroma with confirmed excision may be preferable; 4) traumatic neuroma pain is only partly due to a peripheral source; 5) demographic and neurological variables do not predict success; 6) the presence of a discrete nerve syndrome and mechanical hyperalgesia modestly predict pain relief; 7) ongoing litigation is the strongest predictor of failure; and 8) change in work status is not a likely outcome.
Referral bias in aneurysmal subarachnoid hemorrhage
Authors: Whisnant Jack P. , Sacco Sara E. , O'Fallon W. Michael , Fode Nicolee C. , Sundt Thoralf M. 
Published: May 2009

✓ The objective of this study was to assess the effect of referral bias on survival in patients with subarachnoid hemorrhage (SAH). The characteristics of 49 patients with aneurysmal SAH from a single community were compared with those of 328 patients referred from outside the community, all treated in the same medical care setting. In addition, referral patients who received surgery were compared by differential survival analysis with those still awaiting surgery at Days 1 to 3, Days 4 to 10, and Days 11 to 15.
There was a dramatic difference in the 30-day survival rate between referral patients (83%) and community patients (59%), but most of the difference had occurred by the 2nd day after SAH. In the referral patients, the variables present at first medical attention that were found to have an independent effect on survival were clinical grade, presence of coma, number of days from SAH to referral, diastolic blood pressure, and patient age. There was a higher survival rate at 1 year for patients who were surgically treated compared with those awaiting surgery for each of the three time periods. Patients who underwent early surgical treatment had a 1-year survival rate almost identical to that of patients with late surgery.
Referral patients had a better early survival rate than did community patients because the referral group did not include patients who died and some who were in poor clinical condition before the opportunity for referral. The differential survival analysis described provides a new method for estimating survival for treated and untreated patients with SAH.
Encapsulated intracerebral hematomas: a defined entity
Authors: Roda José M. , Carceller Fernando , Pérez-Higueras Antonio , Morales Carmen 
Published: May 2009

✓ Encapsulated intracerebral hematoma is an interesting and not widely appreciated entity. It can be defined as an intraparenchymal hematoma found in normotensive patients, usually caused by histologically confirmed vascular malformations, characterized by a gradual clinical onset, and presenting a well-defined capsule at operation. One case is presented and 25 previously reported cases are reviewed, all reflecting the above-mentioned characteristics. The hematomas reviewed here occurred in relatively young patients with a mean age of 35 years and a clear male predominance (19 males, seven females).
A ring of contrast enhancement around a lesion of variable density, usually with mass effect and perifocal edema, is the most relevant feature on computerized tomography. Findings on magnetic resonance images are described for the first time in the reported case. A vascular malformation was the most frequent cause found on histological examination (12 of the 26 total cases). No proven cause was found in the remaining 14 cases, although a small vascular malformation, destroyed or thrombosed after rupturing and bleeding, is the most likely etiology in these patients.
A study of safe entry zones via the floor of the fourth ventricle for brain-stem lesions
Authors: Kyoshima Kazuhiko , Kobayashi Shigeaki , Gibo Hirohiko , Kuroyanagi Takayuki 
Published: May 2009

✓ Direct surgery for intra-axial lesions of the brain stem is considered a hazardous procedure, and morbidity of varying degrees cannot be avoided even with partial removal or biopsy. The main causes of morbidity relate to direct damage during removal of the lesion, selection of an entry route into the brain stem, and the direction of brain stem retraction. The authors examined the possibility of making a medullary incision and retracting the brain stem, taking into account the symptomatology and surgical anatomy, and found two safe entry zones into the brain stem through a suboccipital approach via the floor of the fourth ventricle. These safe entry zones are areas where important neural structures are less prominent. One is the “suprafacial triangle,” which is bordered medially by the medial longitudinal fascicle, caudally by the facial nerve (which runs in the brainstem parenchyma), and laterally by the cerebellar peduncle. The second is the “infrafacial triangle,” which is bordered medially by the medial longitudinal fascicle, caudally by the striae medullares, and laterally by the facial nerve. In order to minimize the retraction-related damage to important brain-stem structures, the brain stem should be retracted either laterally or rostrally in the suprafacial triangle approach and only laterally in the infrafacial triangle approach.
Three localized intra-axial brain-stem lesions were treated surgically via the safe entry zones using the suprafacial approach in two and the infrafacial approach in one. The cases are described and the approaches delineated. Both approaches are indicated for focal intra-axial lesions located unilaterally and dorsal to the medial lemniscus in the lower midbrain to the pons. Magnetic resonance imaging is useful in selecting these approaches, and intraoperative ultrasonography is helpful to confirm the exact location of a lesion before a medullary incision is made. These approaches can also be used as routes for aspiration of brain-stem hemorrhage as well as for tumor biopsy.
Arteriovenous fistulas of the brain and the spinal cord
Authors: Tomlinson Francis H. , Rüfenacht Daniel A. , Sundt Thoralf M. , Nichols Douglas A. , Fode Nicolee C. 
Published: May 2009

✓ Arteriovenous (AV) fistulas of cerebral and spinal arteries are characterized angiographically by an immediate AV transition without a capillary bed or “nidus” as occurs in AV malformations (AVM's). The clinical presentation, morphology, radiology, and treatment of 12 patients with cerebral AV fistulas and of 12 patients with spinal AV fistulas are reviewed. In the patients with cerebral lesions, headache and seizure disorders were the most common presentations followed by subarachnoid hemorrhage, cardiac failure, progressive neurological dysfunction, and incidental detection on prenatal ultrasound study. In patients with spinal AV fistulas, weakness and sensory disturbance in the lower extremities were the most frequent clinical presentations followed by back pain, disturbances of micturition, and grand mal seizure. The etiology of the symptom complex produced by AV fistulas in each of these locations differed, with venous hypertension being important in spinal cord lesions.
Of the patients with cerebral lesions, nine had a single AV fistula, one had two fistulas, and two had multiple fistulas. An AVM was observed in five patients with fistulas (two large, three small). Nine patients exhibited extramedullary AV fistulas of the spine, of whom eight had a single fistula and one had three fistulas; three patients had intramedullary spinal AV fistulas. An arterial aneurysm was found in association with two fistulas, one cerebral and one spinal. Venous ectasias or varices, frequently exhibiting mural calcification, were observed to be prominent in all AV fistulas involving cerebral arteries and in two involving spinal arteries. The location and size of the venous complexes reflected the diameter of the fistula. In addition to conventional imaging techniques (cerebral angiography, computerized tomography, and magnetic resonance (MR) imaging), MR angiography was a helpful adjunct in the evaluation of fistulas. Treatment strategies employed for AV fistulas in both locations included open surgical and endovascular procedures, frequently used in combination. A satisfactory outcome was observed in all patients.
Moyamoya phenomenon after radiation for optic glioma
Authors: Kestle John R. W. , Hoffman Harold J. , Mock Antonio R. 
Published: May 2009

✓ The role of radiotherapy in the management of patients with optic pathway glioma is controversial. In a series of patients with optic pathway glioma treated at The Hospital for Sick Children in Toronto, five children were encountered who developed moyamoya phenomenon after radiotherapy. A retrospective review of the medical records was undertaken in order to assess the relationship between optic pathway glioma, neurofibromatosis type 1 (NF1), radiation therapy, and moyamoya disease.
Forty-seven patients with optic pathway glioma were operated on at The Hospital for Sick Children between 1971 and 1990. The moyamoya phenomenon did not occur in any of the 19 patients not receiving radiotherapy. Among the 28 patients who received radiotherapy, five developed moyamoya disease (two of 23 without NF1 and three of five with NF1). There was a statistically significant relationship between radiotherapy and moyamoya disease when the analysis was stratified according to the presence of NF1 (Mantel-Haensel chi-squared test 15.23, p < 0.01). The high incidence of moyamoya disease (three of five cases, or 60%) in patients with NF1 who have undergone radiotherapy suggests a synergistic relationship that should be considered when formulating a treatment plan for NF1 patients with optic pathway glioma.