Etiology and Management of Recurrent and Persistent Hemifacial Spasm-A Single-Center Experience.

BACKGROUND AND OBJECTIVES: Despite a 90% success rate, microvascular decompression occasionally fails to resolve hemifacial spasm (HFS), necessitating revision surgery. We investigated recurrent cases to identify underlying causes. METHODS: We evaluated patients at our institution who underwent revision microvascular decompression because of recurrent or persistent HFS, assessing recurrence causes, decompression techniques, complications, and outcomes. Data considered included demographics, preoperative symptoms, disease duration, offending vessel, and magnetic resonance findings. Surgical notes and intraoperative videos were reviewed, and telephone interviews were conducted for recent outcomes. RESULTS: Out of our ongoing series of 493 patients, 43 patients (8.7%) required revision surgery with a patient cohort of 33 females and 10 males. The average symptom duration was 10 years. The median time between primary and revision surgery was 14 months. Thirteen patients (30.2%) underwent initial surgery elsewhere. Adhesions of Teflon pledgets to the facial nerve were the primary cause of nonresolution in 23 patients (53.5%), while in 13 (30.2%), a missed vascular compression was identified. Sixteen patients (37.2%) had sufficient decompression by removing the conflicting pledgets. During 10 revisions (23.3%), additional Teflon pledgets were necessary. After a median follow-up of 67 months after revision surgery, 27 patients (62.8%) reported complete spasm resolution. Six patients (14.0%) had a good outcome with over 90% reduction of their spasms, 3 patients (7.0%) stated a fair outcome (50% improvement), while 7 patients (16.3%) had no improvement. CONCLUSION: According to our results, adhesions of Teflon to the facial nerve may cause HFS recurrence. Therefore, whenever possible, Teflon should be placed without nerve contact between the brainstem and the offending vessel. Using a sling or bridge technique seems to be beneficial because it leaves the facial nerve completely free. Persistent symptoms often result from missed offending vessels in the pontomedullary sulcus indicating the benefit of endoscopic inspection of this area with an endoscope.

Endoscope-Assisted Microsurgery for Posterior Fossa Skull Base Meningioma Surgery: Technique and Results.

BACKGROUND AND OBJECTIVES: Surgery of posterior fossa meningiomas is extremely challenging even for experienced skull base surgeons because of the close proximity to cranial nerves and tight spaces. Endoscope-assisted surgery for posterior fossa meningiomas can enable a high degree of tumor resection even when using small approaches. This study describes the advantage of endoscope-assisted microneurosurgery in resection of posterior fossa skull base meningiomas and the clinical outcome. METHODS: All endoscope-assisted surgeries for resection of posterior fossa meningiomas performed between 2002 and 2016 in our department were retrospectively analyzed. For data acquisition, the patient files were used. Tumor size and extent of resection were evaluated on pre- and postoperative magnetic resonance imaging. The value of endoscope assistance was assessed according to the intraoperative videos and the surgical notes. Complications and long-term outcomes were evaluated. RESULTS: We identified 39 female and 10 male patients. The mean age of the patients at the time of surgery was 55 years, ranging from 25 to 78 years. The mean follow-up was 93.8 months. A total of 41% of the tumors were large to giant. The retrosigmoid approach was used in most patients (45). A gross total resection could be achieved in 38 patients (78%). In 11 patients (22%), a near total resection was performed. In 27 patients (55%), a hidden residual tumor, which could not been visualized with the operating microscope, was identified with the endoscope. In 6 patients (22.2%), the internal auditory canal was visualized, in 9 patients (33.3%), the Meckel's cave was visualized, and in 5 patients (18.5%), both were visualized under endoscope assistance. In 26 of those patients (96.3%), the residual tumor was resected under endoscopic view. CONCLUSION: Endoscope-assisted surgery for posterior fossa skull base meningiomas enables a high degree of tumor resection, avoids more invasive skull base approaches, and reduces the amount of cerebellar retraction.

Preemptive strategies and lessons learned from complications encountered with microvascular decompression for hemifacial spasm.

OBJECTIVE: Microvascular decompression (MVD) is the only curative treatment modality for hemifacial spasm (HFS). Although generally considered to be safe, this surgical procedure is surrounded by many risks and possible complications. The authors present the spectrum of complications that they met in their case series, the possible causes, and the strategies recommended to minimize them. METHODS: The authors reviewed a prospectively maintained database for MVDs performed from 2005 until 2021 and extracted relevant data including patient demographics, offending vessel(s), operative technique, outcome, and different complications. Descriptive statistics with uni- and multivariable analyses for the factors that may influence the seventh, eighth, and lower cranial nerves were performed. RESULTS: Data from 420 patients were obtained. Three hundred seventeen of 344 patients (92.2%) with a minimum follow-up of 12 months had a favorable outcome. The mean follow-up (standard deviation) was 51.3 ± 38.7 months. Immediate complications reached 18.8% (79/420). Complications persisted in only 7.14% of patients (30/420) including persistent hearing deficits (5.95%) and residual facial palsy (0.95%). Temporary complications included CSF leakage (3.10%), lower cranial nerve deficits (3.57%), meningitis (0.71%), and brainstem ischemia (0.24%). One patient died because of herpes encephalitis. Statistical analyses showed that the immediate postoperative disappearance of spasms and male gender are correlated with postoperative facial palsy, whereas combined vessel compressions involving the vertebral artery (VA) and anterior inferior cerebellar artery can predict postoperative hearing deterioration. VA compressions could predict postoperative lower cranial nerve deficits. CONCLUSIONS: MVD is safe and effective for treating HFS with a low rate of permanent morbidity. Proper patient positioning, sharp arachnoid dissection, and endoscopic visualization under facial and auditory neurophysiological monitoring are the key points to minimize the rate of complications in MVD for HFS.

Endoscope-assisted microsurgical resection of a third ventricular immature teratoma.

BACKGROUND: Reaching a tumor within the third ventricle is challenging, and planning an accessible trajectory is crucial without injuring the surrounding structures. We report a 5-year-old boy presented with headache and a seizure where sequential MRI brain studies in a short time period revealed a rapid growing immature teratoma within the third ventricle with hydrocephalic changes. Several management procedures were performed for CSF diversion and medical treatment of the tumor with chemotherapy and stem cell therapy. The tumor was rapidly growing, and surgical excision was decided. Total resection was achieved via endoscope-assisted microsurgical transcallosal approach. Seven years after surgery, the patient experienced no recurrence of the tumor with a favorable clinical condition. CONCLUSION: We report a rare case of posterior third ventricular immature teratoma where the endoscope-assisted microsurgical technique was implemented with favorable long-term postoperative outcome.

The value of intraoperative indocyanine green angiography in microvascular decompression for hemifacial spasm to avoid brainstem ischemia.

PURPOSE: Despite being rarely reported, ischemic insults resulting from compromising small brainstem perforators following microvascular decompression (MVD) remain a potential devastating complication. To avoid this complication, we have been using indocyanine green (ICG) angiography intraoperatively to check the flow within the small brainstem perforators. We aim to evaluate the safety and usefulness of ICG videoangiography in MVD. METHODS: We extracted retrospective data of patients who received ICG videoangiography from our prospectively maintained database for microvascular decompression. We noted relevant data including demographics, offending vessels, operative technique, outcome, and complications. RESULTS: Out of the 438 patients, 15 patients with a mean age (SD) of 53 ± 10.5 years underwent intraoperative ICG angiography. Male:female was 1:1.14. The mean disease duration prior to surgery was 7.7 ± 5.3 years. The mean follow-up (SD) was 50.7 ± 42.0 months. In 14 patients, the offending vessel was an artery, and in one patient, a vein. Intraoperative readjustment of the Teflon pledget or sling was required in 20% (3/15) of the cases. No patient had any sort of brainstem ischemia. Eighty percent of the patients (12/15) experienced complete resolution of the spasms. 86.7% (13/15) of the patients reported a satisfactory outcome with marked improvement of the spasms. Three patients experienced slight hearing affection after surgery, which improved in two patients later. There was no facial or lower cranial nerve affection. CONCLUSION: Intraoperative ICG is a safe tool for evaluating the flow within the brain stem perforators and avoiding brainstem ischemia in MVD for hemifacial spasm.

Pineal cysts without hydrocephalus: microsurgical resection via an infratentorial-supracerebellar approach-surgical strategies, complications, and their avoidance.

Indications for surgery of pineal cysts without ventriculomegaly are still under debate. In view of the limited data for pineal cyst resection in the absence of hydrocephalus, and the potential risk of this approach, we have analyzed our patient cohort focusing on strategies to avoid complications according to our experience in a series of 73 pineal cyst patients. From 2003 to 2015, we reviewed our database retrospectively for all patients operated on a pineal cyst. Furthermore, we prospectively collected patients from 2016 to 2020. In summary, 73 patients with a pineal cyst were treated surgically between 2003 and 2020. All patients were operated on via a microscopic supracerebellar-infratentorial (SCIT) approach. The mean follow-up period was 26.6 months (range: 6-139 months). Seventy-three patients underwent surgery for a pineal cyst. An absence of enlarged ventricles was documented in 62 patients (51 female, 11 male, mean age 28.1 (range 4-59) years). Main presenting symptoms included headache, visual disturbances, dizziness/vertigo, nausea/emesis, and sleep disturbances. Complete cyst resection was achieved in 59/62 patients. Fifty-five of 62 (89%) patients improved after surgery with good or even excellent results according to the Chicago Chiari Outcome Scale, with complete or partial resolution of the leading symptoms. Pineal cysts resection might be an indication in certain patients for surgery even in the absence of ventriculomegaly. The high percentage of postoperative resolution of quality-of-life impairing symptoms in our series seems to justify surgery. Preoperatively, other causes of the leading symptoms have to be excluded.

Value of Endoscopic Visualization During the Sling-Transposition Technique for Microvascular Decompression of the Facial Nerve in a Case with Hemifacial Spasm.

Endoscopic visualization during microvascular decompression for hemifacial spasm enables better identification of compression areas along the facial nerve, which is especially important in cases with complex compression and enlarged vessels obscuring the compression site. A 40-year-old man presented with a 10-year history of left hemifacial spasm. Magnetic resonance imaging showed a deep compression site with multiple vessels. Within the narrow space, the compression area was clearly visualized using an angled endoscope. Arterial transposition was performed using a polytetrafluoroethylene (Teflon) sling, which was fixed to the nearby dura using an aneurysm clip. Decompression was visually confirmed using the angled endoscope. The patient was free of spasms directly after surgery with no further complications and no recurrence of spasm during 6-month follow-up (Video 1).

Purely venous compression in trigeminal neuralgia-can we predict the outcome of surgery.

PURPOSE: Controversies regarding venous compression and trigeminal neuralgia (TN) still exist. The study demonstrates our experience for microvascular decompression (MVD) in TN caused by purely venous compression. The goal was to identify prognostic anatomical or surgical factors that may influence the outcome. METHODS: Between 2004 and 2020, 49 patients were operated with purely venous compression. Average age was 58.4 years. Mean history of TN was 7.8 years. Microsurgical procedures included transposition or separation of the vein, coagulation, and division. Several features have been analyzed with respect to BNI scores. RESULTS: Evaluation on discharge revealed a complete pain relief in 39 (80%), partial improvement in 7 (14%), and no benefit in 3 (6%) patients. Facial hypesthesia was reported by 14 (28.6%) patients. Mean follow-up (FU) was 42.1 months. BNI pain intensity score on FU revealed 71.4% excellent to very good scores (score 1: 32 (65.3%); 2: 3 (6.1%)). BNI facial numbness score 2 could be detected in 13 patients (26.5%) during FU. There was no statistical relationship between immediate pain improvement or BNI pain intensity score on FU with respect to surgical procedure, size of trigeminal cistern, type of venous compression, venous caliber, trigeminal nerve indentation, or neurovascular adherence. BNI facial numbness score was dependent on type of venous compression (p < 0.05). CONCLUSION: We did not find typical anatomical features that could either predict or influence the outcome regarding pain improvement or resolution in any form. Neither classic microvascular decompression (interposition/transposition) nor sacrificing the offending vein made any difference in outcome.

A multivariable prediction model for recovery patterns and time course of symptoms improvement in hemifacial spasm following microvascular decompression.

BACKGROUND: Microvascular decompression (MVD) success rates exceed 90% in hemifacial spasm (HFS). However, postoperative recovery patterns and durations are variable. OBJECTIVE: We aim to study factors that might influence the postoperative patterns and duration needed until final recovery. METHOD: Only patients following de-novo MVD with a minimum follow-up of 6 months were included. Overall trend of recovery was modeled. Patients were grouped according to recognizable clinical recovery patterns. Uni- and multivariable analyses were used to identify the factors affecting allocation to the identified patterns and time needed to final recovery. RESULTS: A total of 323 (92.6%) patients had > 90% symptom improvement, and 269 (77.1%) patients had complete resolution at the last follow-up. The overall trend of recovery showed steep remission within the first 6 months, followed by relapse peaking around 8 months with a second remission ~ 16 months. Five main recovery patterns were identified. Pattern analysis showed that evident proximal indentation of the facial nerve at root exit zone (REZ), males and facial palsy are associated with earlier recovery at multivariable and univariable levels. anterior inferior cerebellar artery (AICA), AICA/vertebral artery compressions and shorter disease durations are related to immediate resolution of the symptoms only on the univariable level. Time analysis showed that proximal indentation (vs. distal indentation), males and facial palsy witnessed significantly earlier recoveries. CONCLUSION: Our main finding is that in contrast to peripheral indentation, proximal indentation of the facial nerve at REZ is associated with earlier recovery. Postoperative facial palsy and AICA compressions are associated with earlier recoveries. We recommend a minimum of 1 year before evaluating the final outcome of MVD for HFS.

Long-term outcome and quality of life after CNS cavernoma resection: eloquent vs. non-eloquent areas.

The aim of this study is to analyze the long-term quality of life after surgery of cavernoma. A monocentric retrospective study was conducted on 69 patients with cavernoma treated microsurgically between 2000 and 2016. The eloquence was adopted from Spetzler-Martin definition. A most recent follow-up was elicited between 2017 and 2019, in which the quality of life (QoL) was evaluated with the Short Form-12 questionnaire (SF12). Forty-one lesions were in eloquent group (EG), 22 in non-eloquent group (NEG), 3 in orbit, and 3 in the spinal cord. Postoperative worsening of the modified Rankin scale (mRS) occurred in 19.5% of cases in EG versus 4.5% in NEG. After a mean follow-up of 6.5 years (SD 4.6), the neurological status was better or unchanged compared to baseline in 85.4% of EG and 100% of NEG. Regarding QoL assessment of 44 patients (EG n = 27, NEG n = 14) attended the last follow-up. Patients after eloquent cavernoma resection reported a non-inferior QoL in most SF12 domains (except for physical role) compared to NEG. However, they reported general health perception inferior to norms, which was affected by the limited physical and emotional roles. At a late follow-up, the surgical morbidity was transient in the NEG and mostly recovered in the EG. The QoL comparison between eloquent and non-eloquent cavernomas created interesting and new data after prolonged follow-up. These results add value for decision-making as well as patient counseling for future encountered cases. Preoperative evaluation of QoL is recommended for future studies to assess QoL dynamics.

Outcome of Endoscope-Assisted Microvascular Decompression in Patients With Hemifacial Spasm Caused by Severe Indentation of the Brain Stem at the Pontomedullary Sulcus by the Posterior Inferior Cerebellar Artery.

BACKGROUND: Microvascular decompression (MVD) is the most effective treatment option for hemifacial spasm (HFS). However, deeply located forms of compression would require proper identification to allow for adequate decompression. OBJECTIVE: To describe the usefulness of endoscopic visualization in one of the most challenging compression patterns in HFS, where the posterior inferior cerebellar artery (PICA) loop is severely indenting the brain stem at the proximal root exit zone of facial nerve along the pontomedullary sulcus. METHODS: Radiological and operative data were checked for all patients in whom severe indentation of the brainstem by PICA at pontomedullary sulcus was recorded and endoscope-assisted MVD was performed. Clinical correlation and outcome were analyzed. RESULTS: A total of 58 patients with HFS were identified with radiological and surgical evidence proving brainstem indentation at the VII transitional zone. In 31 patients, PICA was the offending vessel to the facial nerve. In 3 patients, the PICA loop was mobilized under visualization of a 45° endoscope. A total of 31 patients had a mean follow-up duration of 52.1 mo. The mean duration between start of complaints and surgery was 7.2 yr. In the last follow-up, all patients had remarkable spasm improvement. A total of 5 patients had more than 90% disappearance of spasms and 26 patients experienced spasm-free outcome. CONCLUSION: Although severe indentation of brain stem implies morphological damage, outcome after MVD is excellent. A 45° endoscope is extremely helpful to identify compression down at the pontomedullary sulcus. Deeply located compression site can easily be missed with microscopic inspection alone.

Quality of life and olfactory function after suprasellar craniopharyngioma surgery-a single-center experience comparing transcranial and endoscopic endonasal approaches.

The endoscopic endonasal approach to suprasellar craniopharyngiomas has become popular as alternative to transcranial approaches. However, the literature lacks data regarding quality of life and olfactory function. The assessment of the long-term quality of life and olfactory function of all patients harboring a suprasellar craniopharyngioma who underwent surgery in our department has been done. Patient characteristics and perioperative data were gathered in a prospectively maintained database. At the last follow-up visit, the olfactory function and the quality of life (ASBQ, SNOT-22) as well as visual and pituitary function were assessed. Thirteen and 17 patients underwent surgery via a transcranial (T) and endonasal (E) route, respectively. No differences were seen in ASBQ, SNOT-22, and olfactory function between T and E, but in E were more full-time worker and less obesity. CSF leaks occurred in 15% of T and 29% of E (p = 0.43). Patients from group E had a superior visual outcome which was most pronounced in the visual field. The degree of new anterior and posterior pituitary gland deficiency after surgery and in the follow-up was lower in group E. The general and sinonasal quality of life and the olfactory function are equal in E and T. E is associated with a superior visual outcome, lower rates of diabetes insipidus, and lower rates of obesity, but has a higher risk for postoperative CSF leaks.

Pineal Cyst without Hydrocephalus: Clinical Presentation and Postoperative Clinical Course After Infratentorial Supracerebellar Resection.

BACKGROUND: Surgical indications for patients with pineal cysts are controversial. There are absolute indications such as hydrocephalus or tectal compression; otherwise, it is difficult to decide whether surgery would be beneficial when symptoms are not distinct. OBJECTIVE: We tried to clarify the indications and clinical course of patients after resection of pineal cysts without ventriculomegaly. METHODS: We reviewed our database for all patients operated on for pineal cyst without ventriculomegaly from 2003 to 2018. We studied the presenting symptoms, cyst size, surgical approach, extent of resection, and clinical and radiologic follow-up. Follow-up ranged from 3 months to 14 years (mean 3.74 years). RESULTS: Forty-three patients underwent surgery for pineal cyst in absence of ventriculomegaly; 36 female patients, 7 male patients, mean age 25.63 years (±10.62 years, range 4-52 years). Presenting symptoms included headache (41/43), nausea and vomiting (31/43), dizziness (19/43), visual disturbances (10/43), and sleep disturbances (8/43). Mean cyst size was 15.7 mm (±4.9 mm, range 9-27 mm). In total, 41 of 43 patients reported a good outcome, represented by a Chicago Chiari Outcome Scale score of 11 or greater and only 2 of 43 patients reported a bad outcome, defined by Chicago Chiari Outcome Scale score of 10 or less. CONCLUSIONS: We suggest that pineal cysts without ventriculomegaly are an indication for surgery when patients present with headache and/or visual disturbances and other causes have been excluded. Resolution of symptoms and quality of life in our cohort may denote a good indication for resection. However, we must admit that there is still no evidence to recommend this technique as a treatment of headache in these patients.

Endoscopic Endonasal Transmaxillary Transsphenoidal Approach for Excision of a Superior Orbital Fissure-Cavernous Sinus Meningioma: 2-Dimensional Operative Video.

We present a 43-old-male who suffered from a slowly progressive loss of vision in the left eye. Magnetic resonance (MR) imaging revealed a well-circumscribed contrast-enhancing lesion in the region of the anterior cavernous sinus and superior orbital fissure that extended into the optic canal. A schwannoma or meningioma was suspected. A transcranial surgery performed at another institution was not successful in removing the tumor and further deterioration of vision occurred. After resection of the left middle turbinate, the sphenoid and maxillary sinus were opened. The bulging of the tumor was seen at the lateral wall of the sphenoid sinus. After bony decompression of the optic canal, the dura was opened. A meningioma was exposed that arose in between the dural layers of the cavernous sinus. A nice dissection plane was found and the tumor was circumferentially dissected and finally totally removed. There were no complications such as double vision or visual field deficit. MR imaging confirmed a total tumor resection. The visual acuity normalized within a few days. MR imaging obtained 3 yr after surgery shows no recurrence.

Frequency and treatment of hydrocephalus prior to and after posterior fossa tumor surgery in adult patients.

BACKGROUND: There is paucity of information about the frequency of hydrocephalus prior to and after posterior fossa tumor surgery in adult patients and about the best way it should be managed. The present study was conducted to determine the frequency of hydrocephalus prior to and after posterior fossa tumor surgery in adult patients as well as the value of an endoscopic third ventriculostomy (ETV) prior to posterior fossa tumor surgery with regard to the rate of perioperative complications and persistent hydrocephalus. METHODS: A single-institution retrospective chart review of all posterior fossa tumor surgeries of our department in a 10-year period (2005 to 2014) has been done. RESULTS: Fifty-two of 243 adult patients with posterior fossa tumors presented with hydrocephalus at the time of admission prior to tumor surgery. 39/52 received early tumor surgery, 11/52 an ETV prior to tumor surgery and in 2/52 an external ventricular drainage (EVD) was inserted prior to tumor surgery. 3/52 patients required a permanent cerebrospinal fluid (CSF) diverting procedure for persistent hydrocephalus after tumor removal. One hundred ninety-one patients did not demonstrate a hydrocephalus before surgical treatment and four of them developed a post-resection hydrocephalus. CONCLUSION: The frequency of hydrocephalus prior to posterior fossa tumor surgery in adult patients is 21.4% and therefore much lower than in respective reports of pediatric patients. The risk of persistent hydrocephalus and newly developed hydrocephalus after tumor surgery was very low, too (5.7 and 2.1%, respectively). An ETV is not justified in every adult patient prior to posterior fossa tumor surgery.

Microvascular Decompression for Patients With Hemifacial Spasm Associated With Common Trunk Anomaly of the Cerebellar Arteries-Case Study and Review of Literature.

BACKGROUND: Few previous studies have described the origin of both anterior and posterior inferior cerebellar arteries from one vessel as a common trunk anomaly. No previous studies have clearly described the aforementioned anomaly depending on intraoperative endoscopic visualization. OBJECTIVE: To evaluate the association of a common trunk anomaly with hemifacial spasm, which makes microvascular decompression more challenging. METHODS: All patients with common trunk anomaly associated with hemifacial spasm who received surgical treatment between 2006 and 2015 in our institution were identified in our prospectively collected database. Detection of the common trunk anomaly was performed using the intraoperative high-definition endoscopic inspection and confirmed by a retrospective review of the obtained operative videos. RESULTS: Out of 248 cases of hemifacial spasm, 21 cases with a common trunk anomaly were detected, with an incidence rate of 8.5%. In 6 cases, the spasm was caused by more than 1 offending vessel "complex compression." In 19 cases, total recovery occurred on follow-up, while in 1 case, 90% recovery occurred. One patient was spasm-free immediately after surgery, but died 3 wk after operation from herpes encephalitis. CONCLUSION: Common trunk anomaly in hemifacial spasm is rare. The surgical technique is mostly identical to decompression with normally arising vessels. However, in case of a bifurcation situated close to the compression site where the offending vessel cannot be transposed freely, an extensive cushioning along the trunk and the offending vessels with teflon pledgets should be performed. The presence of a common trunk anomaly does not affect the surgical results.

Heat Generation During Bony Decompression of Lumbar Spinal Stenosis Using a High-Speed Diamond Drill with or without Automated Irrigation and an Ultrasonic Bone-Cutting Knife: A Single-Blinded Prospective Randomized Controlled Study.

OBJECTIVE: The main objective of the present prospective, randomized, single-blinded controlled study was to measure heat during bony decompression of lumbar spinal stenosis with high-speed drills and an ultrasonic bone-cutting knife. METHODS: Ninety patients diagnosed with lumbar spinal stenosis were included in this study and randomized for lumbar spinal canal decompression using either a high-speed drill with automatic irrigation, high-speed drill with manual irrigation, or an ultrasonic bone-cutting knife with automatic irrigation (USBCD). For evaluation of group homogeneity, a visual analog scale pain score and neurologic findings were measured preoperatively and postoperatively. Temperatures during bony decompression were measured using a forward-looking infrared camera system. RESULTS: Clinical results among the 3 groups did not differ in pain reduction, improvement of neurologic findings, or the rate of complications. However, significantly lower values were found for absolute and mean maximal temperatures during bony decompression in the USBCD group compared with the groups of patients who received the high-speed drill with automatic irrigation and the high-speed drill with manual irrigation, indicating this technique to be less aggressive in terms of thermal induction of bone necrosis. USBCD allows more precise bone removal compared with high-speed drills, and despite increased device time, no significant difference in the overall decompression time was observed. CONCLUSIONS: All methods examined produced short temperature peaks with possible, at least temporary, damage to bone and neural tissue. Automatic irrigation was associated with lower heat development compared with manual irrigation. Despite evidence of critical temperatures, no clinical correlation (e.g., neurologic deficits) was encountered in this study. Clinically, all 3 methods presented equally good results.

A New Score to Predict the Risk of Hearing Impairment After Microvascular Decompression for Hemifacial Spasm.

BACKGROUND: Intraoperative monitoring of brainstem auditory evoked potentials (BAEPs) has been implemented to reduce the risk of hearing impairment during microvascular decompression for hemifacial spasm. OBJECTIVE: To evaluate intraoperative monitoring of BAEPs during microvascular decompression in patients with hemifacial spasm for predicting the risk of hearing impairment after surgery. METHODS: This prospective study included 100 patients. BAEPs were recorded for all patients. We established a scoring system for the changes in wave I amplitude, I-III interpeak latency, and wave V amplitude and latency. For each change, total points were calculated, and a score out of 6 was assigned to every patient. We classified the patients based on the points scored into 3 risk groups: low-risk (0-3), medium-risk (4-5), and high-risk (6). Further, the correlation between the score and the hearing outcome was evaluated to detect the incidence and degree of hearing impairment. RESULTS: Eighty-seven patients scored 0 to 3, 10 scored 4 to 5, and 3 scored 6. The degree of hearing impairment was proportionate to the score recorded at the end of surgery, and patients in the low-risk group showed no impairment; medium-risk group, deterioration of maximum 2 grades according to World Health Organization classification of hearing impairment; and high-risk group, deterioration of 3 to 4 grades. CONCLUSION: Intraoperative monitoring of BAEPs evaluated through our scoring system was valuable in predicting hearing impairment after surgery.