Simultaneous microvascular decompression for trigeminal neuralgia and hemifacial spasm involving a dolichoectatic vertebral artery in an elderly patient: illustrative case.

BACKGROUND: Hyperactive cranial neuropathies refractory to medical management can often be debilitating to patients. While microvascular decompression (MVD) surgery can provide relief to such patients when an aberrant vessel is compressing the root entry zone (REZ) of the nerve, the arteries of elderly patients over 65 years of age can be less amenable to manipulation because of calcifications and other morphological changes. A dolichoectatic vertebral artery (DVA), in fact, can lead to multiple cranial neuropathies; therefore, a strategy for MVDs in elderly patients is useful. OBSERVATIONS: A 76-year-old man presented with medically refractory trigeminal neuralgia (TN) and hemifacial spasm (HFS). A DVA was the conflicting vessel at the left REZs of the trigeminal and facial nerves. The authors performed a retrosigmoid craniotomy for MVD of the DVA with Teflon padding at both REZs in approximately 1 hour of operative time. The patient was free of facial pain and spasm immediately after surgery and at follow-up. LESSONS: The authors described the case of an elderly patient with both TN and HFS caused by compression of a DVA. Simultaneous MVD with Teflon padding at both REZs provided symptomatic relief with limited surgical time. This can be a particularly useful and straightforward surgical strategy in the elderly population.

Intermediate nerve neuralgia developed during hemifacial spasm follow-up: illustrative case.

BACKGROUND: Intermediate nerve neuralgia (INN) is a rare condition believed to be caused by vascular compression, with external auditory canal pain as the chief symptom. The authors reported a rare case of a 78-year-old woman who developed INN during follow-up for hemifacial spasm (HFS). OBSERVATIONS: The patient had been receiving Botox treatment for right HFS for 20 years when she developed paroxysmal electric shock pain in the right external auditory canal and tinnitus induced by opening her mouth. A three-dimensional magnetic resonance fusion image showed the cisternal portion of the facial-vestibulocochlear nerve complex to be compressed by the meatal loop of the anterior inferior cerebellar artery (AICA), which was pressed against by the posterior inferior cerebellar artery. The authors diagnosed INN, and microvascular decompression (MVD) was performed. Surgical findings were consistent with preoperative neuroimaging. In addition, the proximal portion of the meatal loop of the AICA had passed between the facial and vestibulocochlear nerves, compressing both. The AICA was moved and the nerve completely decompressed. All symptoms improved immediately following surgery. LESSONS: When INN occurs during HFS follow-up, aggressive MVD should be considered based on detailed neuroimaging. This treatment is a very effective single-stage cure for INN, HFS, and vestibulocochlear symptoms.

Computational hemodynamic analysis of the offending vertebral artery at the site of neurovascular contact in a case of hemifacial spasm associated with subclavian steal syndrome: illustrative case.

BACKGROUND: Hemifacial spasm (HFS) is caused by neurovascular contact along the facial nerve's root exit zone (REZ). The authors report a rare HFS case that was associated with ipsilateral subclavian steal syndrome (SSS). OBSERVATIONS: A 42-year-old man with right-sided aortic arch presented with progressing left HFS, which was associated with ipsilateral SSS due to severe stenosis of the left brachiocephalic trunk. Magnetic resonance imaging showed contact between the left REZ and vertebral artery (VA), which had shifted to the left. The authors speculated that the severe stenosis at the left brachiocephalic trunk resulted in the left VA's deviation, which was the underlying cause of the HFS. The authors performed percutaneous angioplasty (PTA) to dilate the left brachiocephalic trunk. Ischemic symptoms of the left arm improved after PTA, but the HFS remained unchanged. A computational fluid dynamics study showed that the high wall shear stress (WSS) around the site of neurovascular contact decreased after PTA. In contrast, pressure at the point of neurovascular contact increased after PTA. LESSONS: SSS is rarely associated with HFS. Endovascular treatment for SSS reduced WSS of the neurovascular contact but increased theoretical pressure of the neurovascular contact. Physical release of the neurovascular contact is the best treatment option for HFS.

Utilization of 3D imaging reconstructions and assessment of symptom-free survival after microvascular decompression of the facial nerve in hemifacial spasm.

OBJECTIVE: Hemifacial spasm (HFS), largely caused by neurovascular compression (NVC) of the facial nerve, is a rare condition characterized by paroxysmal, unilateral, involuntary contraction of facial muscles. It has long been suggested that these symptoms are due to compression at the transition zone of the facial nerve. The aim of this study was to examine symptom-free survival and long-term quality of life (QOL) in HFS patients who underwent microvascular decompression (MVD). A secondary aim was to examine the benefit of utilizing fused MRI and MRA post hoc 3D reconstructions to better characterize compression location at the facial nerve root exit zone (fREZ). METHODS: The authors retrospectively analyzed patients with HFS who underwent MVD at a single institution, combined with a modified HFS-7 telephone questionnaire. Kaplan-Meier analysis was used to determine event-free survival, and the Wilcoxon signed-rank test was used to compare pre- and postoperative HFS-7 scores. RESULTS: Thirty-five patients underwent MVD for HFS between 2002 and 2018 with subsequent 3D reconstructions of preoperative images. The telephone questionnaire response rate was 71% (25/35). If patients could not be reached by telephone, then the last clinic follow-up date was recorded and any recurrence noted. Twenty-four patients (69%) were symptom free at longest follow-up. The mean length of follow-up was 2.4 years (1 month to 8 years). The mean symptom-free survival time was 44.9 ± 5.8 months, and the average symptom-control survival was 69.1 ± 4.9 months. Four patients (11%) experienced full recurrence. Median HFS-7 scores were reduced by 18 points after surgery (Z = -4.013, p < 0.0001). Three-dimensional reconstructed images demonstrated that NVC most commonly occurred at the attached segment (74%, 26/35) of the facial nerve within the fREZ and least commonly occurred at the traditionally implicated transition zone (6%, 2/35). CONCLUSIONS: MVD is a safe and effective treatment that significantly improves QOL measures for patients with HFS. The vast majority of patients (31/35, 89%) were symptom free or reported only mild symptoms at longest follow-up. Symptom recurrence, if it occurred, was within the first 2 years of surgery, which has important implications for patient expectations and informed consent. Three-dimensional image reconstruction analysis determined that culprit compression most commonly occurs proximally along the brainstem at the attached segment. The success of this procedure is dependent on recognizing this pattern and decompressing appropriately. Three-dimensional reconstructions were found to provide much clearer characterization of this area than traditional preoperative imaging. Therefore, the authors suggest that use of these reconstructions in the preoperative setting has the potential to help identify appropriate surgical candidates, guide operative planning, and thus improve outcome in patients with HFS.

A history of the Jannetta procedure.

Peter Jannetta was a neurosurgery resident when he proposed the neurovascular compression theory. He built upon the astute observations of Dandy, Gardner, and others who, in the era before the operating microscope, had successfully ventured into the posterior fossa. In 1965, Jannetta performed cranial nerve microdissections for dental students and identified the trigeminal portio intermedia. He proposed that preservation of these sensory fibers may avoid complete facial numbness, and together with Robert Rand developed a subtemporal transtentorial approach for selective rhizotomy for trigeminal neuralgia (TN). Such rash surgery, using an operating microscope, was then forbidden at their University of California, Los Angeles center, so they collaborated with John Alksne to perform the first surgery at Harbor General Hospital. Upon visualizing the trigeminal nerve root, Jannetta was surprised to see a pulsating superior cerebellar artery compressing the nerve and said "That's the cause of the tic." He also hypothesized that alleviating the observed vascular cross-compression may be curative.A few months later, while assessing a patient with hemifacial spasm, Jannetta had the epiphany that this was the same disease process as TN, but instead affecting the facial nerve. The patient consented to what would become Jannetta's first microvascular decompression procedure. The senior faculty members who had forbidden such surgery were away, so the supervising neurosurgeon, Paul Crandall, granted the approval to perform the surgery and assisted. Via a retromastoid approach with the patient in the sitting position and using the operating microscope, Jannetta identified and alleviated the culprit neurovascular compression, with a cure resulting.Jannetta presented his neurovascular compression theory and operative findings to the neurosurgical patriarchy of the time. Elders of the field were generally not inclined to accept the bold speculations of an untested neurosurgeon, and were often determined to discredit the new "cure" of the old diseases. Over decades of refining his surgical technique, documenting the outcomes, and enduring the skepticism he often faced, Jannetta's theory and his microvascular decompression procedure withstood critical analysis and have become recognized as one the great discoveries and advances in neurosurgery and medicine.

Fully endoscopic microvascular decompression for hemifacial spasm.

OBJECTIVE: Hemifacial spasm (HFS) is characterized by involuntary tonic and/or clonic contractions of facial nerve muscles. Fully endoscopic microvascular decompression (E-MVD) for HFS has not been widely adopted. This paper aims to illustrate the safety and efficacy of the fully endoscopic technique for HFS treatment. METHODS: The authors conducted a single-center retrospective study of 27 patients (28 separate E-MVD cases; 1 patient had bilateral E-MVD) diagnosed with HFS who underwent fully E-MVD from January 2013 to October 2016. Intraoperative brainstem auditory evoked potentials and lateral spread resolution were reviewed. Outcome was based on the clinical status of the patient at the last contact point with the senior author. Complications were categorized as facial weakness, hearing loss, ataxia, dysphagia, or any adverse event able to be attributed to the surgical procedure. RESULTS: HFS was relieved either completely or partially in the majority of cases (24 of 28, 85.7%). Of the 28 separate procedures, 17 (60.7%) resulted in complete resolution of symptoms, 4 (14.3%) resulted in near-complete resolution, 2 (7.1%) resulted in 50% reduction of symptoms, 1 (3.6%) resulted in minimal reduction, and 4 (14.3%) resulted in no relief. Of the 27 patients, 26 (96%) had no permanent postoperative complications. In multivariate logistic regression, the best predictor of greater than 50% resolution of spasm was resolution of intraoperative lateral spread response. CONCLUSIONS: A fully E-MVD for HFS provides a safe and comprehensive view of the neurovascular conflict. Exclusive use of the endoscope in MVD is both safe and feasible in the treatment of HFS. Attention to lateral spread response monitoring remains an integral part of comprehensive neurosurgical management.

Facial motor evoked potential with paired transcranial magnetic stimulation: prognostic value following microvascular decompression for hemifacial spasm.

OBJECTIVE: Microvascular decompression (MVD) is widely considered the treatment of choice for hemifacial spasm (HFS), but not all patients immediately benefit from it. Numerous electrophysiological tests have been employed to monitor the integrity of the facial nerve prior to, during, and after MVD treatment. The authors sought to verify if facial motor evoked potential (FMEP) with paired transcranial magnetic stimulation (pTMS) can be utilized as a tool to predict prognosis following MVD for HFS. METHODS: FMEP using pTMS was performed preoperatively and postoperatively for 527 HFS patients who underwent an MVD treatment. Various interstimuli intervals (ISIs), which included 2, 10, 20, 25, 30, 75, and 100 msec, were applied for each paired stimulation and pTMS(%) was obtained. A graph of pTMS(%) versus each ISI was drawn for every patient and its pattern was analyzed in accordance with patients' clinical outcomes. RESULTS: With ISIs of 75 and 100 msec, pTMS(%) was physiologically further inhibited, whereas it was relatively facilitated under ISIs of 20, 25, and 30 msec; loss of this specific pattern, that is, further inhibition-relative facilitation, indicated impaired integrity of the facial nerve. Those patients who immediately benefited from an MVD and experienced no relapse tended to show proper restoration of this further inhibition-relative facilitation pattern (p = 0.01). Greater resemblance between the physiological pattern of pTMS(%) and postoperative pTMS(%) was correlated to better outcome (p = 0.019). CONCLUSIONS: A simple linear graph of pTMS(%) versus each ISI may be a helpful tool to predict prognosis for HFS following an MVD.

Hemodynamic features of offending vessels at neurovascular contact in patients with trigeminal neuralgia and hemifacial spasm.

OBJECTIVEOffending vessels at the site of neurovascular contact (NVC) in patients with trigeminal neuralgia (TN) and hemifacial spasm (HFS) may have specific hemodynamic features. The purpose of this study was to investigate the wall shear stress (WSS) of offending vessels at NVCs by conducting a computational fluid dynamics (CFD) analysis.METHODSThe authors retrospectively analyzed the cases of 20 patients (10 with TN and 10 with HFS) evaluated by 3D CT angiography and used the imaging findings for analysis of the hemodynamic parameters. The 3D CFD images were directly compared with the NVCs determined by simulated multifusion images of CT angiogram and MR cisternogram, and operative photos. The magnitudes of the WSS (WSSm) at the proximal (WSSm-p), just-beginning (WSSm-j), contact site (WSSm-s), and distal (WSSm-d) areas of each NVC were analyzed. The ratios of the WSSm-j, WSSm-s, and WSSm-d areas to the WSSm-p area were calculated individually. The direction of the WSS (WSSv) and its temporal variation (WSSvV) were depicted and morphologically compared with the NVC confirmed by simulated images and operative findings.RESULTSThe ratios of WSSm at the just-beginning and the contact site to the proximal area of the NVCs (WSSm-j/WSSm-p and WSSm-s/WSSm-p) were both significantly higher than that at the distal area (WSSm-d/WSSm-p) (p < 0.05). The WSSv and WSSvV at the NVCs showed small variation in a single cardiac cycle, especially along the areas that were in contact with the affected nerve.CONCLUSIONSAreas of relatively high WSSm and temporal variation of WSSm (WSSmV) were observed at the NVCs. Less mobility of the WSSv and WSSvV was detected along the side of the vessels in contact with the nerves. These findings may be consistent with the actual area of the NVC. Hemodynamic features of the site of NVC can be added to the preoperative simulation for MVD surgery, which may be useful for the diagnosis and treatment planning of TN and HFS.

Hemi-laryngopharyngeal spasm as a novel cause of inducible laryngeal obstruction with a surgical cure: report of 3 cases.

Inducible laryngeal obstruction has been described under at least 40 different monikers, including vocal cord dysfunction, paroxysmal vocal fold motion, and irritable larynx. The etiology of this condition is believed to be laryngeal hyperactivity in response to psychological issues or acid reflux. Most patients are treated with some combination of proton pump inhibitors, speech therapy, and psychotherapy. However, a small cohort of patients remains refractory to all medical interventions. The authors describe a novel condition, hemi-laryngopharyngeal spasm (HELPS), which can cause severe episodic stridor leading to unconsciousness in association with cough. The first recognized and surgically cured patient with HELPS was reported in an earlier issue of this journal. Three additional patients have been followed up for at least a year postoperatively, and their cases are reported here.Each patient presented with a similar pattern of episodic coughing and choking that increased in frequency, severity, and duration over years. The episodes eventually occurred while sleeping and could cause severe stridor with loss of consciousness. All three patients were initially misdiagnosed with a psychiatric illness and subjected to multiple intubations and one tracheostomy. Unilateral botulinum toxin injections in the vocal fold eased the severity of the throat contractions but not the cough. Magnetic resonance imaging showed a looping posterior inferior cerebellar artery juxtaposed to a vagus nerve in each case. Microvascular decompression (MVD) of that vessel relieved all symptoms.The introduction of this new medical condition may help a small cohort of patients with inducible laryngeal obstructions that have not responded to the current standard treatments. Patients are asymptomatic between episodes of progressively severe coughing and choking with stridor that may lead to intubation. Severe anxiety about the unpredictable symptoms is expected and may contribute to a psychiatric misdiagnosis. Microvascular decompression for HELPS is more difficult than that for trigeminal neuralgia because the involved nerve is more susceptible to manipulation. Ultimately, the final proof that HELPS is a real and distinct syndrome will require its recognition and successful treatment by colleagues around the world.

Microvascular decompression for hemifacial spasm: can intraoperative lateral spread response monitoring improve surgical efficacy?

OBJECTIVE The purpose of this study was to evaluate whether intraoperative monitoring of lateral spread response (LSR) improves the efficacy of microvascular decompression (MVD) for hemifacial spasm (HFS). METHODS In this prospective study, patients undergoing MVD for HFS were assigned to one of 2 groups, Group A (MVD with intraoperative LSR monitoring) or Group B (MVD without LSR monitoring). Clinical outcome at 12 months after surgery was assessed through telephone survey. Data analysis was performed to investigate the effect of intraoperative LSR monitoring on efficacy of MVD. RESULTS A total of 283 patients were enrolled in the study, 145 in Group A and 138 in Group B. There was no statistically significant difference between the 2 groups with respect to the percentage of patients who had spasm relief at either 1 week (Group A 87.59% vs Group B 83.33%; p = 0.317) or 1 year (93.1% vs 94.2%; p = 0.809) after surgery. A clear-cut elimination of LSR during surgery was observed in 131 (90.34%) of 145 patients; LSR persisted in 14 patients (9.66%) at the end of the surgical procedure. Disappearance of LSR correlated with spasm-free status at 1 week postoperatively (p = 0.017) but not at 1 year postoperatively (p = 0.249). CONCLUSIONS Intraoperative LSR monitoring does not appear to provide significant benefit with respect to the outcome of MVD for HFS in skilled hands. Persistence of LSR does not always correlate with poor outcome, and LSR elimination should not be pursued in all patients after verification of complete decompression.

An investigation into quality of life improvement in patients undergoing microvascular decompression for hemifacial spasm.

OBJECTIVE Hemifacial spasm (HFS) is a movement disorder characterized by involuntary spasms of the facial muscles, and it can negatively impact quality of life (QOL). This retrospective study and systematic review with meta-analysis was conducted to investigate the QOL in patients with HFS following intervention with microvascular decompression (MVD) and botulinum toxin (BT). METHODS In the retrospective analysis, a QOL questionnaire was administered to all patients undergoing MVD performed by a single surgeon. The QOL questionnaire included unique questions developed based on the authors' experience with HFS patients in addition to the health-related QOL HFS-8 questionnaire. The authors also report on a systematic review of the English literature providing outcomes and complications in patients with HFS undergoing treatment with either MVD or BT. RESULTS Regarding the retrospective analysis, 242 of 331 patients completed the questionnaire. The mean score of the 10 QOL questions improved from 22.78 (SD 9.83) to 2.17 (SD 5.75) following MVD (p < 0.001). There was significant improvement across all subscales of the questionnaire between pre- and postoperative responses (p < 0.001). Regarding the systematic review, it is reported that approximately 90% of patients undergoing MVD for HFS experience a complete recovery from symptoms, whereas the mean peak improvement of symptoms following treatment with BT is 77%. Furthermore, patients undergoing MVD reported a greater improvement in the mean supplemental index of QOL as compared with patients receiving BT therapy. CONCLUSIONS Microvascular decompression offers a significant improvement in QOL in well-selected patients suffering from HFS, and may offer an increased benefit for QOL over BT injections.

"Birdlime" technique using TachoSil tissue sealing sheet soaked with fibrin glue for sutureless vessel transposition in microvascular decompression: operative technique and nuances.

OBJECTIVE Microvascular decompression (MVD) is effective for the treatment of trigeminal neuralgia (TN), hemifacial spasm (HFS), and glossopharyngeal neuralgia. The transposition technique is the standard procedure to avoid adhesions and granuloma around the decompression site but is more complex and difficult to perform than the interposition technique. The authors describe a simple and safe MVD transposition procedure they call the "birdlime" technique, which uses a tissue glue-coated collagen sponge soaked with fibrin glue, and the results of this technique. METHODS The authors retrospectively reviewed the medical charts and radiographic findings of 27 consecutive patients with TN (8 patients) and HFS (19 patients) who, between January 2012 and December 2015, had undergone an MVD transposition procedure utilizing a tissue glue-coated collagen sponge (TachoSil tissue sealing sheet) soaked with fibrin glue (Tisseel 2-component fibrin sealant, vapor heated). Offending arteries among the patients with TN were the superior cerebellar artery (SCA) in 5 patients, the SCA and anterior inferior cerebellar artery (AICA) in 2, and the AICA in 1. Those among the patients with HFS were the vertebral artery (VA) in 3 patients, the VA and AICA in 4, the VA and posterior inferior cerebellar artery (PICA) in 3, the PICA in 4, the AICA in 1, the AICA-PICA in 3, and the PICA and AICA in 1. Operations were performed according to the Jannetta procedure. The offending artery was transposed and fixed to the dura mater of the petrous bone using TachoSil pieces soaked with fibrin glue. Postoperative constructive interference in steady-state MRI was performed to evaluate the change in the position of the offending artery. RESULTS Transposition of the offending artery was easily and safely performed in all patients. All patients had total remission of symptoms directly after the procedure. No severe complications occurred. The postoperative course was uneventful. No recurrences, adhesions, or dysfunction of the cranial nerves was observed in any of the patients. Postoperative MRI showed that the offending vessels were displaced and fixed in the appropriate position. CONCLUSIONS The described transposition technique provides an easy and adjustable way to perform MVD safely and effectively. In addition, this transposition and fixation technique is simple and avoids the risk of needle injury close to the cranial nerves and vessels. This simple sutureless technique is recommended for MVD to reduce the risk of intraoperative neurovascular injury.

Delayed facial palsy after microvascular decompression for hemifacial spasm: friend or foe?

OBJECTIVE The authors investigated the incidence, clinical course, and predisposing factors associated with delayed facial palsy (DFP) following microvascular decompression (MVD). METHODS The authors reviewed the records of 310 patients (311 cases) who were followed after MVD for hemifacial spasm (HFS). Of these patients, 45 (14.5%) developed DFP after MVD. The clinical characteristics and predisposing factors of the patients with HFS were investigated to identify prognostic factors that predicted the development of DFP after MVD. Log-rank tests were used to compare times to symptom disappearance, and a logistic regression analysis was performed to compare clinical characteristics between patients who developed DFP and those who did not. RESULTS HFS was completely resolved immediately after MVD in 158 cases (50.8%), and HFS eventually disappeared in 289 (92.9%) of the cases. Of the 45 patients with DFP, 17 were men and 28 were women. DFP occurred between postoperative Days 1 and 44 (mean 9.67 days). Finally, 44 patients (97.8%) completely recovered. The average time to recovery was 3.9 months (range 1-24 months). Patients who had experienced an immediate disappearance of HFS experienced a significantly higher occurrence of DFP than those who did not (odds ratio 0.383, 95% confidence interval 0.183-0.802; p = 0.011). In addition, preoperative botulinum neurotoxin injections negatively influenced the occurrence of DFP (p = 0.016). CONCLUSIONS In this study, the incidence rate of DFP was slightly higher than previously reported values. Moreover, DFP can occur even when spasms disappear immediately after MVD, but the patients with DFP can fully recover within weeks.

Utility of the intensive care unit in patients undergoing microvascular decompression: a multiinstitution comparative analysis.

OBJECTIVE Use of the ICU during admission to a hospital is associated with a significant portion of the total health care costs for that stay. Patients undergoing microvascular decompression (MVD) for cranial neuralgias are routinely admitted postoperatively to the ICU for monitoring. The primary purpose of this study was to compare complication rates of patients with and without a postoperative ICU stay following MVD. The secondary intents were to identify predictors of complications, to analyze variables of health care resource utilization, and to estimate the cost of postoperative management. METHODS The authors performed a retrospective comparative analysis of consecutive patients undergoing MVD at 2 institutions. A total of 199 patients without a postoperative ICU stay from Institution A and 119 patients with an ICU stay from Institution B were reviewed. Inclusion criteria included any adult (i.e., 18 years of age or older) undergoing MVD for trigeminal neuralgia, hemifacial spasm, glossopharyngeal neuralgia, or geniculate neuralgia. Patients with incomplete medical records were excluded. Medical comorbidities, intraoperative variables, complications, postoperative interventions, and variables indicating health care resource utilization were reviewed. RESULTS The study compared 190 patients without a postoperative ICU stay from Institution A with 90 patients with an ICU stay from Institution B. Seven patients without an ICU stay and 5 patients with an ICU stay experienced complications after surgery (p = 0.53). Multivariate analysis identified coronary artery disease to be a predictor of complications (p = 0.037, OR 6.23, 95% CI 1.12-34.63). Patients from Institution A without a postoperative ICU stay had a significantly shorter length of stay, by approximately 16 hours (p < 0.001), and received less postoperative imaging (p < 0.001, OR 14.39, 95% CI 7.75-26.74) and postoperative diagnostic testing (p < 0.001) than patients from Institution B with an ICU stay. Estimated cost savings in patients without an ICU stay and 1 less day of inpatient recovery was calculated as $1400 per patient. CONCLUSIONS Selective versus routine use of ICU care as well as postoperative imaging and diagnostic testing may be safe after MVD and can lead to a reduction in overall health care costs.

Analysis of facial motor evoked potentials for assessing a central mechanism in hemifacial spasm.

OBJECTIVE Hemifacial spasm (HFS) is a cranial nerve hyperactivity disorder characterized by unique neurophysiological features, although the underlying pathophysiology remains disputed. In this study, the authors compared the effects of desflurane on facial motor evoked potentials (MEPs) from the spasm and nonspasm sides of patients who were undergoing microvascular decompression (MVD) surgery to test the hypothesis that HFS is associated with a central elevation of facial motor neuron excitability. METHODS Facial MEPs were elicited in 31 patients who were undergoing MVD for HFS and were administered total intravenous anesthesia (TIVA) with or without additional desflurane, an inhaled anesthetic known to centrally suppress MEPs. All measurements were completed before dural opening while a consistent mean arterial blood pressure was maintained and electroencephalography was performed. The activation threshold voltage and mean amplitudes of the MEPs from both sides of the face were compared. RESULTS There was a significantly lower mean activation threshold of facial MEPs on the spasm side than on the nonspasm side (mean ± SD 162.9 ± 10.1 vs 198.3 ± 10.1 V, respectively; p = 0.01). In addition, MEPs were also elicited more readily when single-pulse transcranial electrical stimulation was used on the spasm side (74% vs 31%, respectively; p = 0.03). Although desflurane (1 minimum alveolar concentration) suppressed facial MEPs on both sides, the suppressive effects of desflurane were less on the spasm side than on the nonspasm side (59% vs 79%, respectively; p = 0.03), and M waves recorded from the mentalis muscle remained unchanged, which indicates that desflurane did not affect the peripheral facial nerve or neuromuscular junction. CONCLUSIONS Centrally acting inhaled anesthetic agents can suppress facial MEPs and therefore might interfere with intraoperative monitoring. The elevated motor neuron excitability and differential effects of desflurane between the spasm and nonspasm sides support a mechanism of central pathophysiology in HFS. Clinical trial registration no.: B2012:099 ( clinicaltrials.gov ).

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.

Episodic hemilaryngopharyngeal spasm (HELPS) syndrome: case report of a surgically treatable novel neuropathy.

The authors describe a novel cranial neuropathy manifesting with life-threatening episodic hemilaryngopharyngeal spasm (HELPS). A 50-year-old woman presented with a 4-year history of intermittent throat contractions, escalating to life-threatening respiratory distress. Botulinum toxin injections into her right vocal cord reduced the severity of her spasms, but the episodes continued to occur. MRI demonstrated a possible neurovascular conflict involving the cranial nerve IX-X complex and the posterior inferior cerebellar artery. Microvascular decompression of the upper rootlets of the vagal nerve eliminated her HELPS without complication. The authors propose a mechanism of HELPS implicating isolated involvement of the upper motor rootlets of the vagus nerve.

Prognostic ability of intraoperative electromyographic monitoring during microvascular decompression for hemifacial spasm to predict lateral spread response outcome.

OBJECTIVE Abnormal lateral spread response (LSR) is a typical finding in facial electromyography (EMG) in patients with hemifacial spasm (HFS). Although intraoperative monitoring of LSR has been widely used during microvascular decompression (MVD), the prognostic value of this monitoring is still debated. The purpose of this study was to determine whether such monitoring exhibits prognostic value for the alleviation of LSR after treatment of HFS. METHODS Between January 2009 and December 2013, a total of 582 patients underwent MVD for HFS with intraoperative EMG monitoring at Kyung Hee University Hospital. The patients were categorized into 1 of 2 groups according to the presence of LSR at the conclusion of surgery (Group A, LSR free; Group B, LSR persisting). Patients were assessed for the presence of HFS 1 day, 6 months, and 1 year after surgery. Various parameters, including age, sex, symptom duration, offending vertebral artery, and offending perforating artery, were evaluated for their influence on surgical and electrophysiological results. RESULTS Overall, HFS was alleviated in 455 (78.2%) patients 1 day after MVD, in 509 (87.5%) patients 6 months after MVD, and in 546 (93.8%) patients 1 year after MVD. Patients in Group B were significantly younger than those in Group A (p = 0.022). Patients with a symptom duration of less than 1 year were significantly more likely to be classified in Group A than were patients whose symptoms had persisted for longer than 10 years (p = 0.023); however, analysis of the entire range of symptom durations did not reveal a significant effect (p = 0.132). A comparison of Groups A and B according to follow-up period revealed that HFS recovery correlated with LSR alleviation over a shorter period, but the same was not true of longer periods; the proportions of spasm-free patients were 80.6% and 71.1% (p = 0.021), 89.4% and 81.9% (p = 0.022), and 93.5% and 94.6% (p = 0.699) 1 day, 6 months, and 1 year after surgery in Groups A and B, respectively. CONCLUSIONS Although intraoperative EMG monitoring during MVD was beneficial for identifying the offending vessel and suggesting the most appropriate surgical end point, loss of LSR did not always correlate with long-term HFS treatment outcome. Because the HFS cure rate improved over time, revision might be considered for persistent LSR when follow-up has been performed for more than 1 year and the spasm remains despite adequate decompression.

Real-time intraoperative monitoring of brainstem auditory evoked potentials during microvascular decompression for hemifacial spasm.

OBJECTIVE The aim of this study was to define a new protocol for intraoperative monitoring (IOM) of brainstem auditory evoked potentials (BAEPs) during microvascular decompression (MVD) surgery to treat hemifacial spasm (HFS) and to evaluate the usefulness of this new protocol to prevent hearing impairment. METHODS To define the optimal stimulation rate, estimate the number of trials to be averaged, and identify useful warning criteria in IOM of BAEPs, the authors performed a preliminary study of 13 patients with HFS in 2010. They increased the stimulation rate from 10.1 Hz/sec to 100.1 Hz/sec by 10-Hz increments, and they elevated the average time from 100 times to 1000 times by 100-unit increments at a fixed stimulus rate of 43.9 Hz. After defining the optimal stimulation rate and the number of trials that needed to be averaged for IOM of BAEPs, they also identified the useful warning criteria for this protocol for MVD surgery. From January to December 2013, 254 patients with HFS underwent MVD surgery following the new IOM of BAEPs protocol. Pure-tone audiometry and speech discrimination scoring were performed before surgery and 1 week after surgery. To evaluate the usefulness of the new protocol, the authors compared the incidence of postoperative hearing impairment with the results from the group that underwent MVD surgery prior to the new protocol. RESULTS Through a preliminary study, the authors confirmed that it was possible to obtain a reliable wave when using a stimulation rate of 43.9 Hz/sec and averaging 400 trials. Only a Wave V amplitude loss > 50% was useful as a warning criterion when using the new protocol. A reliable BAEP could be obtained in approximately 9.1 seconds. When the new protocol was used, 2 patients (0.8%) showed no recovery of Wave V amplitude loss > 50%, and only 1 of those 2 patients (0.39%) ultimately had postoperative hearing impairment. When compared with the outcomes in the pre-protocol group, hearing impairment incidence decreased significantly among patients who underwent surgery with the new protocol (0.39% vs 4.02%, p = 0.002). There were no significant differences between the 2 surgery groups regarding other complications, including facial palsy, sixth cranial nerve palsy, and vocal cord palsy. CONCLUSIONS There was a significant decrease in postoperative hearing impairment after MVD for HFS when the new protocol for IOM of BAEPs was used. Real-time IOM of BAEPs, which can obtain a reliable BAEP in less than 10 seconds, is a successful new procedure for preventing hearing impairment during MVD surgery for HFS.

Failed microvascular decompression surgery for hemifacial spasm due to persistent neurovascular compression: an analysis of reoperations.

OBJECT Microvascular decompression (MVD) surgery for hemifacial spasm (HFS) is potentially curative. The findings at repeat MVD in patients with persistent or recurrent HFS were analyzed with the aim to identify factors that may improve surgical outcomes. METHODS Intraoperative findings were determined from review of dictated operative reports and operative diagrams for patients who underwent repeat MVD after prior surgery elsewhere. Clinical follow-up was obtained from the hospital and clinic records, as well as telephone questionnaires. RESULTS Among 845 patients who underwent MVD performed by the senior author, 12 had been referred after prior MVD for HFS performed elsewhere. Following repeat MVD, all patients improved and complete spasm resolution was described by 11 of 12 patients after a mean follow-up of 91 ± 55 months (range 28-193). Complications were limited to 1 patient with aggravation of preexisting hearing loss and mild facial weakness and 1 patient with aseptic meningitis without sequelae. Significant factors that may have contributed to the failure of the first surgery included retromastoid craniectomies that did not extend laterally to the sigmoid sinus or inferiorly to the posterior fossa floor in 11 of 12 patients and a prior surgical approach that focused on the cisternal portion of the facial nerve in 9 of 12 patients. In all cases, significant persistent neurovascular compression (NVC) was evident and alleviated more proximally on the facial root exit zone (fREZ). CONCLUSIONS Most HFS patients will achieve spasm relief with thorough alleviation of NVC of the fREZ, which extends from the pontomedullary sulcus root exit point to the Obersteiner-Redlich transition zone.