Transtemporal Venous Decompression for Idiopathic Venous ...

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Abstract
Objective
To evaluate the clinical characteristics and present surgical outcomes of transtemporal venous decompression technique in the treatment of pulsatile tinnitus (PT).
Study Design
This is a prospective cohort study.
Setting
This study was done at the tertiary private neurotologic skull base clinic.
Participants
The primary author, between March 2012 and February 2013, evaluated 55 patients with the complaint of PT. Seven out of the 55 patients were diagnosed with severe, unrelenting idiopathic pulsatile tinnitus (IPT), and were placed into the study. These seven patients had temporal bone computed tomography, magnetic resonance imaging, arteriogram, videonystagmography, electrocochleography, and lumbar puncture based on the symptoms. All the seven patients underwent transtemporal venous decompression surgery.
Main Outcome Measure
Resolution of PT was determined as the primary outcome measure.
Results
Six out of seven patients had complete resolution of their PT immediately after surgery and at 3 to 4 years follow-up. One patient developed intracranial hypertension after 3 months requiring ventriculoperitoneal shunt, which resolved PT as well. No complications occurred.
Conclusion
A significant subset of the PT patient population has known reversible causes. The more common includes conductive hearing loss, superior canal dehiscence, benign intracranial hypertension, jugulosigmoid venous anomalies, stapedial myoclonus, etc. There exists a subset of patients who have IPT. Transtemporal venous decompression is a surgical technique that can be employed to give patients with IPT long-term relief.
PT is described as a conscious and undesired perception of the heartbeat in the ear.
1
Patients with pulsatile or pulse-synchronous tinnitus comprise ∼4% of tinnitus cases.
23
PT is associated with many identifiable causes such as atherosclerotic carotid artery disease, glomus tumor, aneurysms, arteriovenous malformations, jugular bulb abnormalities, sigmoid sinus wall defects, diverticulum, superior semicircular canal dehiscence, and conductive hearing loss. These entities have been successfully treated in the past with various medical and surgical techniques.
45
Intracranial venous diverticulum as a cause of PT has been treated successfully with endovascular treatment. These include venous sinus stenting and coil embolization.
6
Lenck et al described stenting of stenosis of the lateral sinus for PT in patients with a stenotic lesion. These lesions are difficult to diagnose and require transvenous monography, and should be included in the differential of patients with PT.
7
There exists a population of patients with PT where a definitive cause cannot be identified and for which symptoms are refractory to conventional treatment. This subset of patients is diagnosed with IPT. Cognitive therapy and vasoactive medications have shown unsatisfactory results in managing symptoms of patients with IPT.
8
Bae et al treated 10 patients with IPT using tinnitus-retraining therapy, 9 of the 10 patients experienced incomplete resolution of PT.
9
Internal jugular vein ligation had shown success in treating IPT initially, but is strongly discouraged due to high recurrence rate and serious complications such as florid intracranial hypertension.
10111213
PT also occurs in ∼60% of patients with idiopathic intracranial hypertension (IIH).
14
Although typical symptoms of IIH consist of headaches or visual disturbances, PT alone, or in association with hearing loss, dizziness, and aural fullness, has also been recognized as a manifestation of this condition.
151617
Acetazolamide and other medical treatments are successful in treating mild to moderate IIH, but PT is known to persist.
18
Cerebrospinal fluid diversion surgeries can treat PT in IIH patients, but these procedures are indicated in severe cases of advancing vision loss, debilitating headaches, and progressing neurological symptoms.
192021
Various surgical treatments have been used to treat PT secondary to venous anomalies, such as sigmoid sinus diverticulum, sigmoid sinus wall defects (dehiscence, thinning), and dominant sigmoid sinus.
22
Guo and Wang reported 24 patients treated by transmastoid venous compression of dominant sigmoid sinus in patients with PT. Most patients had significant resolution, but 8 of the 24 persisted with PT.
23
Contrary to the above-mentioned causes of PT, IPT has no successful medical or surgical treatment. The persistent nature and lack of effective treatment for IPT can significantly affect health and quality of life, leading to depression and even suicidal ideations in severe cases.
24
In this article, we address diagnosis and treatment of patients with IPT that is severe and intractable, despite multifarious attempts toward their management.
We propose transtemporal venous decompression as a surgical technique for treatment of PT in patients with IPT. This surgical treatment is proposed to be successful, by removing the bone over the area of the fixed wall in the sigmoid sinus responsible for the turbulent sound.
Materials and Methods
A prospective cohort clinical study was performed in a tertiary neurotologic skull base clinic from March 2012 to February 2013. The study was approved by the Seton Institutional Review Board of the Seton Family of Hospitals (CR-10-059).
Patient History and Physical Examination
The primary author evaluated a total of 55 patients complaining of unilateral PT. Detailed patient history along with demographic data, physical examinations of the ear, head, and neck regions were performed. Body mass index (BMI) was recorded (
Table 1
). Audiograms and tympanograms were performed to exclude serous otitis media or any other causes of conductive hearing loss. Tinnitus severity was categorized based on Tinnitus Handicap Inventory (THI). Light digital pressure was applied over the ipsilateral internal jugular vein and its effect on loudness of PT was recorded.
Seven of these 55 patients were identified who required further evaluation from a diagnostic standpoint due to negative findings. In six of the seven patients, it was observed that on application of light digital pressure over ipsilateral internal jugular vein or turning head to the same side, loudness of PT either diminished or resolved. Patient 5 did not observe any change. These seven patients were further evaluated using magnetic resonance venography (MRV), magnetic resonance angiography (MRA), 4-vessel arteriogram, videonystagmography, and electrocochleography based on individual requirements. Lumbar puncture (LP) was performed for all the seven patients to rule out IIH.
Medical Therapy
Medical therapy was determined based on the most likely cause of IPT specific to each patient. Two of these seven patients were prescribed niacin for their PT. One patient suspected to have (Meniere's disease) was treated with transtympanic steroids. Two patients were treated with acetazolamide for suspected intracranial hypertension. None of these patients observed any reduction in PT. The remaining two of the seven patients had IPT associated with mild elevated lumbar puncture opening pressure (LPOP; <30 cm/water). No other symptoms such as headache, blurring of vision, vision loss, papilledema, or morbid obesity of ICH were observed. These patients were encouraged to lose weight and low salt diet was advised. These two patients were treated with more aggressive doses of acetazolamide for up to 2 months. Acetazolamide treatment was discontinued after a maximum of 2 months, or if side effects necessitated the termination of therapy. There was no improvement in the severity of PT. Ventriculoperitoneal (VP) shunt was not indicated due to the absence of other morbid symptoms.
Operative Procedure
The primary author preformed all procedures, with the patient under general anesthesia. Standard postauricular incision was utilized with the patient in the supine position. The sigmoid sinus was skeletonized from the tegmen/sinodural angle as far inferior as possible to the jugular bulb. Dura was decompressed posterior and anterior to the sigmoid 1/2 cm as far inferior as possible. Emissary veins were obliterated when encountered. The venous system was meticulously decompressed to avoid venous trauma. If bone on the venous system was not practical to remove in total, it was left as thin as possible and in segments as small as possible. These segments were usually less than 2 to 3 mm in diameter (
Fig. 2
). The wound was closed in layers, without mastoid dressing. The patient was observed either in intensive care unit or a step-down unit, for 24 hours postoperatively. All patients were discharged on the first or second postoperative day.
Completed dural and venous decompression from sinodural angle to the jugular bulb region.
Results
Mean age was 52 years, and mean duration of PT was 27.2 months. Mean follow-up duration postsurgery was 33.4 months (
Table 1
). Audiogram showed preoperative average speech recognition threshold of 25 dB and postoperative speech recognition threshold of 26 dB. Preoperative pure tone average was 26 dB and postoperative was 28 dB in the operative ear. This shows a trend lower in the postoperative ear but is within test variability. Three out of seven patients had 10 to 15 dB difference in hearing compared with the nonsurgical ear. Two out of seven patients had 40 to 50 dB of low-frequency sensorineural hearing loss compared with the nonaffected ear.
Mean THI pre- and postsurgeries were 4.8 and 1.2, respectively. Six out of seven patients had complete resolution of PT immediately postsurgery and remained symptom free regardless of positioning or activity in the final evaluation at 3 to 4 years follow-up (
Table 2
).
Patient number 7 obtained almost 50% (THI grade 3) improvement immediately postsurgery and at 2 months follow-up. Her symptoms returned to preoperative level after 3 months postoperatively. This patient's preoperative LPOP was 26 cm/water. Postoperative LP and MRV were performed after 5 months. It was noted that her opening pressure had remained stable at 27 cm/water and postoperative MRV showed normal venous patency (
Fig. 3
). She complained of persistent PT and had developed headaches. The patient was referred to a neurologist and treated medically for IIH, eventually requiring a VP shunt. This resolved PT and headache.
Discussion
This is a prospective clinical study, in which six of seven patients, diagnosed with severe unrelenting IPT, were successfully treated by transtemporal venous decompression. One patient, number 7, had significant resolution of PT initially. She had significant weight gain postoperatively, and developed symptoms consistent with IIH.
Medical histories, physical examination, and imaging studies are important for differentiating the origin of PT. We identified seven patients, who were either nonresponsive to conventional medical treatment or had no identifiable cause for their PT.
Idiopathic Pulsatile Tinnitus
Although PT has varied etiologies, often no underlying pathology can be identified.
252627
Herraiz and Aparicio identified 10 such cases out of 80 and were diagnosed with “idiopathic” PT.
28
Extensive imaging studies are suggested in cases of subjective idiopathic PT, where no risk factors can be identified in the patient's medical history or physical examination.
2930
All our seven patients were diagnosed with idiopathic PT. Two had mild elevation LPOP, but still classified as idiopathic. Imaging and LP were performed for all seven patients. As stated previously, severity of PT in all our patients graded very severe to catastrophic (THI). One patient had suicidal ideations secondary to the IPT.
Several authors have advocated that if PT disappears on ipsilateral jugular vein compression, it signifies a venous cause. If it does not, an arterial cause exists.
1431
Patient 5 in our study did not observe any change in PT on ipsilateral compression of internal jugular vein. We believe that compression of jugular vein can be an important criterion for identifying venous PT but is not absolute. The compression strength may vary between clinicians, and strong neck compression may also decrease the arterial flow, resulting in lesser tinnitus.
32
On the contrary, too weak compression may not even be able to alter the jugular flow. Patient's anxiety and environmental sounds are other factors. Krishnan et al attempted to classify 16 patients with PT by compression of internal jugular vein but were unable to categorize 50% of the investigated patients because of the vague response of the patients.
33
Complete resolution of PT immediately postsurgery in this patient 5, without any complications, suggests venous origin. Resolution in this patient suggests a venous cause, even though preoperative venous compression had no effect on the PT. Thus, compression testing may indicate origin of PT but is not absolute.
A venous cause of IPT is the probable source, and this characteristic of IPT makes ligation of the ipsilateral internal jugular vein, a very tempting procedure. There are various reports in the literature describing successful resolution of IPT in patients who underwent internal jugular vein ligation.
3435363738
Duvillard et al argued that internal jugular vein ligation should be avoided because the jugular vein represents the dominant channel of cerebral venous outflow and its ligation poses a theoretical risk of causing intracranial hypertension.
39
It is also observed that this procedure has a high initial success, but high delayed failure rate, presumably due to the rapid development of collateral venous flow around the level of ligation, particularly through mastoid and condylar emissary veins.
40
Jackler et al also concluded that there is rarely, if ever, an indication for this procedure solely for the purpose of alleviating PT, and we agree.
22
Idiopathic Pulsatile Tinnitus with Mild IIH
Mild IIH was a factor in our cohort. Two out of seven patients were diagnosed with IPT with mild IIH. Both patients were obese females. Association of intracranial hypertension with obesity is well documented in the literature.
414243
Both patients were advised and had attempted weight loss in the past without success. Weight loss benefits patients with ICH, but its effect on PT, particularly in mild IIH patients is unknown. In addition, both patients were below the BMI requirements for bariatric surgery.
44
LPOP in the two patients with IIH was 26 and 29 cm/water. LP of 25 cm/water or more is considered diagnostic of increased intracranial pressure.
45
The classic symptoms of IIH include headache, visual disturbance, and PT; however, all the symptoms are rarely collectively present in each individual patient.
14
Our two patients with mild increase LPOP had only PT as a complaint.
Imaging abnormalities associated with raised intracranial hypertension include empty sella, tight subarachnoid spaces, flattening of the posterior globe, protrusion of the optic nerve head, and distension of the optic nerve sheath.
4647
Imaging was unremarkable for both our patients. It is likely that they were diagnosed early in course of the disease; well before any of these imaging signs appeared. This also highlights the important role otolaryngologists can play in identifying intracranial hypertension, before appearance of more severe morbid signs and symptoms.
Carbonic anhydrase inhibitors, such as acetazolamide, are the main medical treatment prescribed for intracranial hypertension and its symptoms.
14849
Acetazolamide dosage was graduated from 125 mg bid up to 1,000 mg a day in our patients. Both patients with IIH were treated with acetazolamide as the first line of treatment, without affecting the PT.
Shaw and Million in their series reported two patients with PT associated with IIH. They observed a complete resolution of symptoms of IIH, including PT, with acetazolamide therapy. As per their report, one of these patients remained symptom free for 1 year and the other was followed up for a few weeks.
14
Biousse et al reported two patients treated with acetazolamide for IIH. They noted that acetazolamide did help with headaches but the PT returned after 3 to 4 months, although it was intermittent and not as loud as before.
50
Vivo et al reported similar results, where two female patients were treated with acetazolamide for IIH. One patient observed an improvement in MRI findings such as restoration of optic nerve sheath thickness and bilateral optic papilla. However, both patients reported persistent moderate to severe episodes of tinnitus during the 10- and 12-month follow-up.
18
Although acetazolamide is a mainstay treatment for intracranial hypertension, it appears inadequate in treating PT associated with mild IIH.
Cerebrospinal fluid diversion techniques, using ventricular shunts, have been used to dissipate the increased intracranial pressure to prevent catastrophic vision loss and/or debilitating headaches or disabling PT.
51
For patient 7, PT returned to preoperative level after 3 months. LPOP repeated at 5 months postoperatively was stable at 27 cm/water. This patient had normal CT, brain MRI, and MRA preoperatively. Postoperative MRV showed negative findings (
Fig. 3
). She experienced debilitating headaches, which were not present preoperatively. PT returned to her baseline level, as she had a significant weight gain, despite weight control measures. The patient was referred to a neurologist, and was prescribed a combination of maximal dosages of topiramate and acetazolamide. Severity of symptoms led to the decision of placing a VP shunt. VP shunt resolved both the headache and the PT in this patient.
High-Riding/Dehiscent Jugular Bulb
Although suggestions are that the symptom of PT from IPT occurs in the area of the jugular bulb,
3452
it is our premise that PT emanates from the area of the sigmoid sinus, most likely from the mid-portion in the mastoid cavity.
The incidence of high-riding jugular bulb and dehiscent jugular bulb ranges from 3.5 to 22.6%, respectively. Patients with high jugular bulb can be completely asymptomatic or may suffer from dizziness, PT, and hearing loss.
53
Various surgical treatments have been used with the aim to create a barrier and provide a sound proofing from the dehisced jugular bulb. El-Begermy and Rabie, in their case series, treated PT due to high dehiscent jugular bulb by layered reconstruction of the bony hypotympanum. Four of seven patients reported resolution of PT, and two patients reported change in character of tinnitus to whistling without improvement. One patient developed severe increase of intracranial pressure requiring treatment, but there was no improvement in PT symptoms.
54
In another study, three patients with PT with a high and dehiscent jugular bulb were treated with transcanal jugular bulb resurfacing technique, using hydroxyapatite. Two patients associated the onset of their symptoms with trauma. All the patients noted immediate improvement in PT.
55
It is possible that patients successfully treated by various surgical repairs of the high and dehisced jugular bulb actually augmented the flow pattern within the mastoid sigmoid segment that is responsible for PT. Surgical management of the dehisced jugular bulb is difficult and can lead to venous obstruction and problematic bleeding.
Surgical Treatment of PT Due to Sigmoid Sinus Wall Defects
Surgical treatments have been used to treat PT for sigmoid anomalies. Kim et al treated eight patients suffering from vascular PT resulting from diverticulum and/or thinning/dehiscence of the sigmoid sinus wall. The sigmoid sinus was compressed and transmastoid reshaping was performed. Seven patients in this study obtained resolution of PT symptoms. One patient suffered a postoperative complication of increased intracranial hypertension requiring decompression of sigmoid sinus.
56
There are other similar techniques reported in the literature performed on patients with diverticulum/dehiscence involving skeletonization of the sigmoid sinus, adjacent dura, and diverticulum.
575859
Our study patient cohort had no sigmoid sinus wall defects or diverticulum.
The exact location of where venous hum arises is unclear. Cho et al conducted three-dimensional reconstruction of the venous system in patients with PT. The authors indicated that PT is caused due to turbulence, which could arise from irregularity in the diameter, vessel curvature, or elasticity of the vessel.
27
We believe that as the blood flows from transverse sinus to S-shaped curvature of sigmoid sinus, it creates an area of turbulence. Venous decompression in this area changes the turbulent flow of blood, perceived as PT, to a more laminar flow, which in turn helps eliminate PT. It also most likely allows venous distension, thus augmenting the venous flow.
Sigmoid Sinus Decompression for Other Conditions
Sigmoid sinus decompression surgery is not new to the realm of skull base surgeries. It has been performed successfully in the past for treatment of other conditions. Gianoli et al performed decompression of sigmoid sinus as a part of sac vein decompression technique to treat Meniere's disease in 35 patients. There were no reported complications or adverse effects at 2 years follow-up.
60
Ostrowski and Kartush reported long-term 55 months follow-up in 56 patients who underwent sac vein decompression. None of the patients reported any complications.
61
We have used a similar form of this technique in the successful treatment of IPT.
Limitations
Our study has limitations. Postoperative LPOP, MRV/MRA, and MRI were not routinely performed.
Conclusion
This procedure is highly effective and displays excellent long-term (3–4 years) complete resolution. Patient selection is systematic, and patients who will most benefit can be identified. IPT can be successfully, safely, and definitively treated by performing transtemporal venous decompression, when conservative management fails and symptoms are severe. Our results also suggest transtemporal venous decompression may be effective for PT related to other venous anomalies such as dehisced jugular bulb and sigmoid venous dehiscence.