Microvascular decompression for typewriter tinnitus-case report

Typewriter Tinnitus: Value of ABR as a Diagnostic and Prognostic Indicator

INTRODUCTION

Typewriter tinnitus refers to a special kind of staccato tinnitus, which is mostly described by patients as Morse code, popcorn, or machine-gun. It has been accepted that the mechanism of typewriter tinnitus is caused by the neurovascular compression of the cochleovestibular nerve. Patients who suffered from typewriter tinnitus have exhibited a good response to carbamazepine or oxcarbazepine, but there is a risk of recurrence after treatment cessation. The present study aims to determine the value of auditory brainstem response (ABR) in diagnosing typewriter tinnitus and predicting relapse after drug withdrawal.

METHODS

Patients who presented with typewriter tinnitus from March 2019 to March 2022 were included for the present retrospective study. The auditory and vestibular test results and drug treatment effects were collected and analyzed. Patients with idiopathic unilateral subjective tinnitus, who were matched by age to patients with typewriter tinnitus at a ratio of 2:1, were consecutively recruited for the control group.

RESULTS

Eighteen patients with typewriter tinnitus and 38 controls were included. Ears with typewriter tinnitus had longer interpeak latency (IPL) I-III, and wave III and V latencies, and a higher ratio of IPL I-III ≥2.3 ms based on ABR, when compared to the unaffected side and controls ( p <0.05). Seventeen patients with typewriter tinnitus responded positively to medication. Among these patients, seven patients had a relapse after drug cessation, while 10 patients did not have a relapse. The relapse group had significantly longer IPL I-III and wave V latency, older age, and poorer hearing, when compared to the nonrelapse group ( p < 0.05). Furthermore, IPL I-III had the largest area under the receiver operating characteristic curve, and the optimal cutoff was 2.4 ms (sensitivity, 100.0%; specificity, 66.7%). There were no significant differences in other demography or other clinical test results between the relapse and nonrelapse groups ( p > 0.05). Ramsay Hunt syndrome and neuromyelitis optica spectrum disorders were identified in two cases.

CONCLUSION

Prolonged IPL I-III based on ABR can help in the diagnosis of typewriter tinnitus and its prognosis after treatment cessation. Patients with IPL I-III greater than 2.4 ms, older age and poorer hearing are more likely to relapse. In addition to the neurovascular conflict of the cochleovestibular nerve, the etiologies of neuroinflammation and demyelinating diseases are also possible for typewriter tinnitus.

Routine postoperative admission to the neurocritical intensive care unit after microvascular decompression: necessary or can it be abandoned?

Postoperative neurocritical intensive care unit (NICU) admission of patients who underwent craniotomy for close observation is common practice. In this study, we performed a comparative analysis to determine if there is a real need for NICU admission after microvascular decompression (MVD) for cranial nerve disorders or whether it may be abandoned. The present study evaluates a consecutive series of 236 MVD surgeries performed for treatment of trigeminal neuralgia (213), hemifacial spasm (17), vagoglossopharyngeal neuralgia (2), paroxysmal vertigo (2), and pulsatile tinnitus (2). All patients were operated by the senior surgeon according to a standard protocol over a period of 12 years. Patients were admitted routinely to NICU during the first phase of the study (phase I), while in the second phase (phase II), only patients with specific indications would go to NICU. While 105 patients (44%) were admitted to NICU postoperatively (phase I), 131 patients (56%) returned to the ward after a short stay in a postanaesthesia care unit (PACU) (phase II). Specific indications for NICU admission in phase I were pneumothorax secondary to central venous catheter insertion (4 patients), AV block during surgery, low blood oxygen levels after extubation, and postoperative dysphagia and dysphonia (1 patient, respectively). There were no significant differences in the distribution of ASA scores or the presence of cardiac and pulmonary comorbidities like congestive heart failure, arterial hypertension, or chronic obstructive pulmonary disease between groups. There were no secondary referrals from PACU to NICU. Our study shows that routine admission of patients after eventless MVD to NICU does not provide additional value. NICU admission can be restricted to patients with specific indications. When MVD surgery is performed in experienced hands according to a standard anaesthesia protocol, clinical observation on a neurosurgical ward is sufficient to monitor the postoperative course. Such a policy results in substantial savings of costs and human resources.

Application of ABR in pathogenic neurovascular compression of the 8th cranial nerve in vestibular paroxysmia

PURPOSE

To investigate the clinical value of electrophysiological tests in indicating pathogenic vascular contact of the 8th nerve in definite vestibular paroxysmia (VP) cases to provide a reference for decompression surgery.

METHODS

We retrospectively analyzed patients who had vertigo, unilateral tinnitus, or hearing loss and exhibited vascular contact of the 8th cranial nerve by MRI. Participants were classified into the VP or non-VP group according to the criteria of the Bárány Society in 2016. The demographic characteristics and audiological and electrophysiological test results of the two groups were compared. Receiver operating characteristic (ROC) curves were calculated for ABR to determine the best parameters and cutoff values to predict the existence of pathological neurovascular contact in VP.

RESULTS

Thirteen patients in the VP group and 66 patients in the non-VP group were included. VP patients had longer interpeak latency (IPL) I-III and wave III latency compared to non-VP patients (p < 0.001; p < 0.001). According to the ROC analyses, IPL I-III and wave III latency were the best indicators for the diagnosis of VP. The optimal cutoff for IPL I-III was 2.3 ms (sensitivity 84.6%, specificity 95.5%), and that for wave III latency was 4.0 ms (sensitivity 92.3%, specificity 77.3%). There were no differences in the PTA, caloric test, o-VEMP, or c-VEMP results between the two groups.

CONCLUSION

Prolonged IPL I-III and the wave III latency of ABR strongly suggested that vascular contact of the 8th cranial nerve was pathological, which may provide some references for microvascular decompression surgery of VP.

Microvascular decompression: is routine postoperative CT imaging necessary?

BACKGROUND

Postoperative head CT imaging is routinely performed for detection of postoperative complications following intracranial procedures. However, it remains unclear whether with regard to radiation exposure, costs, and possibly lack of consequences this practice is truly justified in various operative procedures. The objective of this study was to analyze whether routine postoperative CT imaging after microvascular decompression (MVD) is necessary or whether it may be abandoned.

METHODS

A series of 202 MVD surgeries for trigeminal neuralgia (179), hemifacial spasm (17), vagoglossopharyngeal neuralgia (2), paroxysmal vertigo (2), and pulsatile tinnitus (2) operated by the senior surgeon (JKK) and who had postoperative routine CT imaging was analyzed.

RESULTS

Routine postoperative CT imaging detected small circumscribed postoperative hemorrhage in 9/202 (4.4%) instances. Hemorrhage was localized at the site of the Teflon felt (1/9), the cerebellum (4/9), in the frontal subdural space (3/9), and in the frontal subarachnoid space (1/9). In two patients, asymptomatic hemorrhage was accompanied by mild cerebellar edema (1%), and another patient had mild transient hydrocephalus (0.5%). Furthermore, there were small accumulations of intracranial air in 86/202 instances. No other complications such as infarction or skull fracture secondary to fixation with the Mayfield clamp were detected. MVD had been performed for trigeminal neuralgia in 6/9 patients, for hemifacial spasm in 2/9, and in one patient with both. No patient underwent a second surgery. Hemorrhage was symptomatic at the time of imaging in only one instance who had mild postoperative gait ataxia. Two patients with hemorrhage developed delayed facial palsy most likely unrelated to hemorrhage which remitted with corticosteroid treatment. At 3-month follow-up and at long-term follow-up, they had no neurological deficits.

CONCLUSION

Routine postoperative CT imaging is not necessary after MVD in a standard setting in patients who do not have postoperative neurological deficits.

Typewriter tinnitus: An investigative comparison with middle ear myoclonic tinnitus and its long-term therapeutic response to carbamazepine

OBJECTIVES

Due to its rarity and similar sound, typewriter tinnitus (TT) can be misdiagnosed as middle ear myoclonic tinnitus (MEMT). We aim to clarify the characteristics of TT compared to MEMT, and the long-term therapeutic response to carbamazepine.

METHODS

Fourteen patients with TT and 28 patients with MEMT were enrolled.

RESULTS

TT patients were older than MEMT patients, and their tinnitus symptoms were mostly unilateral. Tinnitus symptoms, which is associated with dizziness, facial spasm, and head motion, were more common in TT, whereas MEMT were more related to noise. Acoustic reflex decay perturbation and low loudness discomfort level were diagnostic signs in MEMT patients, while decreased level of wave II in ABR was the most reliable sign in TT patients. All TT patients exhibited partial or complete response to carbamazepine, but there was a relapse rate after withdrawal of the drug was 60%. Increase in age and longer duration of symptoms were the risk factors of relapse of TT.

CONCLUSION

The different characteristics observed in this study will be helpful to diagnose TT and MENT. Duration of tinnitus was the most important long-term prognostic factor of the carbamazepine trial, which indicates the importance of its earlier diagnosis.

Typewriter tinnitus revisited: The typical symptoms and the initial response to carbamazepine are the most reliable diagnostic clues

Although neurovascular compression of the cochlear nerve (NVC-C) presenting as typewriter tinnitus is a discrete disease category, verified diagnostic criteria are lacking. We sought to refine the diagnostic criteria for NVC-C by reference to a relatively large case series. The medical records of 22 NVC-C patients were retrospectively reviewed. Psychoacoustic characteristics, the results of diagnostic work-up (including audiovestibular neurophysiological tests and radiological evaluations), and the initial treatment response to carbamazepine were investigated. All subjects described their tinnitus as a typical “typewriter” or “staccato” sound. Of the 22 subjects, 11 (50%) had histories of vertiginous spells, but none had ipsilesional hearing loss. Vestibular function tests in 11 subjects tested revealed only 2 (18.2%) isolated cervical vestibular evoked myogenic potential abnormalities. Radiological comparisons of the symptomatic and asymptomatic sides, regarding the type of the vascular loop and neurovascular contact, revealed no significant differences. However, all 22 subjects exhibited immediate and marked responses to short-term carbamazepine treatment. Meticulous history-taking in terms of the psychoacoustic characteristics and the response to initial carbamazepine, are more reliable diagnostic clues than are radiological or neurophysiological data in NVC-C subjects. Therefore, the typical psychoacoustic characteristics and the response to initial carbamazepine should be included in the diagnostic criteria.

The Role of MRI in Diagnosing Neurovascular Compression of the Cochlear Nerve Resulting in Typewriter Tinnitus

BACKGROUND AND PURPOSE

Typewriter tinnitus, a symptom characterized by paroxysmal attacks of staccato sounds, has been thought to be caused by neurovascular compression of the cochlear nerve, but the correlation between radiologic evidence of neurovascular compression of the cochlear nerve and symptom presentation has not been thoroughly investigated. The purpose of this study was to examine whether radiologic evidence of neurovascular compression of the cochlear nerve is pathognomonic in typewriter tinnitus.

MATERIALS AND METHODS

Fifteen carbamazepine-responding patients with typewriter tinnitus and 8 control subjects were evaluated with a 3D T2-weighted volume isotropic turbo spin-echo acquisition sequence. Groups 1 (16 symptomatic sides), 2 (14 asymptomatic sides), and 3 (16 control sides) were compared with regard to the anatomic relation between the vascular loop and the internal auditory canal and the presence of neurovascular compression of the cochlear nerve with/without angulation/indentation.

RESULTS

The anatomic location of the vascular loop was not significantly different among the 3 groups (all, P > .05). Meanwhile, neurovascular compression of the cochlear nerve on MR imaging was significantly higher in group 1 than in group 3 (P = .032). However, considerable false-positive (no symptoms with neurovascular compression of the cochlear nerve on MR imaging) and false-negative (typewriter tinnitus without demonstrable neurovascular compression of the cochlear nerve) findings were also observed.

CONCLUSIONS

Neurovascular compression of the cochlear nerve was more frequently detected on the symptomatic side of patients with typewriter tinnitus compared with the asymptomatic side of these patients or on both sides of control subjects on MR imaging. However, considering false-positive and false-negative findings, meticulous history-taking and the response to the initial carbamazepine trial should be regarded as more reliable diagnostic clues than radiologic evidence of neurovascular compression of the cochlear nerve.

Microvascular decompression for tinnitus: systematic review

OBJECTIVE

The objective of this study was to examine operative outcomes in cases of microvascular decompression (MVD) of cranial nerve (CN) VIII for tinnitus through a critical review of the literature.

METHODS

Forty-three English-language articles were gathered from PubMed and analyzed. In this review, two different case types were distinguished: 1) tinnitus-only symptomatology, which was defined as a patient with tinnitus with or without sensorineural hearing loss; and 2) mixed symptomatology, which was defined as tinnitus with symptoms of other CN dysfunction. This review reports outcomes of those with tinnitus-only symptoms.

RESULTS

Forty-three tinnitus-only cases were found in the literature with a 60% positive outcome rate following MVD. Analysis revealed a 5-year cutoff of preoperative symptom duration before which a good outcome can be predicted with 78.6% sensitivity, and after which a poor outcome can be predicted with 80% specificity.

CONCLUSIONS

As the 60% success rate is more promising than several other therapeutic options open to the chronic tinnitus sufferer, future research into this field is warranted.

Microvascular decompression of the cochleovestibular nerve for treatment of tinnitus and vertigo: a systematic review and meta-analysis of individual patient data

OBJECTIVE Microvascular decompression (MVD) is regarded as a valid treatment modality in neurovascular conflicts (NVCs) causing, for example, trigeminal neuralgia and hemifacial spasms. An NVC of the cochleovestibular nerve might cause tinnitus and/or vertigo; however, general acceptance of MVD for this indication is lacking. The aim of this study was to investigate the effectiveness, safety, and prognostic factors for success of MVD of the cochleovestibular nerve. METHODS A systematic review and meta-analysis of individual patient data (IPD) were conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses and Individual Patient Data (PRISMA-IPD) guidelines. By a comprehensive search (conducted in January 2016) in MEDLINE, EMBASE, and Google Scholar, eligible studies were identified. The collected outcome was a global measurement of improvement of 1) tinnitus, 2) vertigo, and 3) tinnitus combined with vertigo. For the meta-analysis, IPD were collected from the papers and/or from the authors. IPD were analyzed with logistic regression analysis while accounting for study clustering. RESULTS Thirty-five studies (572 patients) were included. The level of evidence provided by these studies was low. In 28% of patients with tinnitus and 32% of patients with vertigo, complete relief following MVD was reported. Patients with both tinnitus and vertigo had complete relief in 62% of cases. In 11% of patients, ≥ 1 complications were reported. Meta-analysis of IPD (165 patients) demonstrated that patients with both tinnitus and vertigo had a higher chance of success (OR 3.8, 95% CI 1.45-10.10) than patients with tinnitus alone. No other variables were significantly related to success. CONCLUSIONS Due to low success rates, MVD cannot be considered as a standard treatment method for tinnitus or vertigo. Moreover, a substantial complication rate was found. However, patients with combined symptoms had a higher chance of success. When combined symptoms occur, it is more likely that an NVC is the underlying pathology and MVD might be appropriate. Due to the low level of evidence in the included studies, this conclusion must be taken with caution. Further validation is necessary to evaluate whether patients with combined symptoms are indeed better candidates for MVD.