Changes in contralateral brain-stem auditory evoked responses to cerebellopontine angle compression in rats

Eleven rats were subjected to graded compression of the brain stem at the cerebellopontine angle (CPA) following craniectomy and cerebellectomy. Clicks were delivered to the ear contralateral to the compression site, and brain-stem auditory evoked responses (BAER's) were collected before and during compression. With increasing compression, there was an increase in the latency and a decrease in the amplitude of the peaks of the BAER. The later peaks of the BAER (V and VI) demonstrated changes with minimal compression that progressed as compression increased, while changes in the amplitude and latency of the earlier peaks (II, III, and IV) occurred at the higher grades of compression. Following decompression of the brain stem, there was a decrease in the latencies of most of the BAER peaks. Peak amplitude remained depressed following brain-stem decompression. These experimental findings corroborate clinical reports of abnormal BAER's elicited from stimulation of the ear contralateral to a CPA tumor. The relative sensitivity of the later peaks of the BAER to even minimal brain-stem compression explains the prolonged III to V interpeak latency reported in the literature in patients with brain-stem compression from a CPA lesion. The possible mechanisms for the BAER changes that were observed contralateral to compression are discussed.     

Prognostic value of auditory brain-stem responses for late postconcussion symptoms following minor head injury

Minor head injury is frequently followed by a subjective postconcussion syndrome. Brain-stem auditory evoked responses (BAER's) were found to be pathological in different small series of patients with a postconcussion syndrome who were examined months after sustaining a slight cranial or cervical trauma; abnormal BAER's have also been reported in larger groups of patients examined early after minor head injury. A relationship between these findings and late subjective symptoms has never been demonstrated. The results of a prospective study into the value of BAER's in the prognosis of a postconcussion syndrome after minor head injury are presented. In 103 patients with minor head injury, BAER's were recorded within 48 hours of the trauma. One year later, the patients were examined for headache, dizziness, depression, anxiety, subjective loss of memory and concentration, and irritability. Eighty percent claimed at least one symptom, most often irritability (54%), memory loss (47%), or depression (39%). Pathological BAER's were found with the same prevalence in patients with and without a postconcussion syndrome. This study confirms the disturbance of brain-stem function in some head-injured patients. However, the lack of correlation with a postconcussion syndrome limits the prognostic value of BAER recordings for postconcussion syndrome. The data suggest that BAER's not be used for medicolegal evaluation of patients with a postconcussion syndrome.     

Assessment of outcome prediction in severe brain damage patients with brainstem auditory evoked response

Patients with various neurological disease resulting in severe brain damage and having Glasgow Coma Scale (G.C.S.) score of less than ten (mean 5.6) were studied with brainstem auditory evoked response (BAER) during the first few days of onset. Among them were subarachnoid hemorrhage, head injury, intracerebral hemorrhage, pontine hemorrhage, intraventricular hemorrhage and bleeding tumor. BAERs were graded into four levels from one (normal) to four (most abnormal). Outcomes were categorized through the Glasgow Outcome Scale. Comparison of the results between BAER and G.C.S. as predictors of outcome was quite similar. Both were reliable in terms of predicting a correctly pessimistic outcome (90% or more), but not a correctly optimistic outcome (40% or less).     

Brain-stem auditory evoked responses in 56 patients with acoustic neurinoma

The brain-stem auditory evoked responses (BAER's) recorded from 56 patients with acoustic neurinomas were analyzed. Ten of the patients had intracanalicular tumors and 46 had extracanalicular tumors. It was possible to obtain BAER's following stimulation of the affected side in 28 patients and after stimulation of the unaffected side in all 56. Five patients (11%) had normal BAER's following stimulation of both sides; three of these patients had intracanalicular tumors. Among BAER's obtained following stimulation of the affected ear, the mean interpeak latency (IPL) for peaks I to III associated with extracanalicular tumors was significantly prolonged relative to controls (p less than 0.001), and linear regression analysis revealed a significant positive correlation between tumor size and IPL of peaks I to III (p less than 0.05). Analysis of the 56 BAER's recorded after stimulation of the unaffected side revealed a significant positive correlation between the IPL's of peaks III to V and tumor size (p less than 0.001). This correlation was not strengthened when accounting for the degree of brain-stem compression. Finally, evidence of preserved function within the auditory pathway, even in the presence of partial hearing loss, is presented. This finding suggests that more patients might benefit from surgical procedures that spare the eighth cranial nerve.     

A comparative study of multimodality evoked potentials and computed tomography in head injuries]

Multimodality evoked potentials (EPs) or three types of EPs--auditory brainstem response (ABR), somatosensory evoked potential (SEP), and visual evoked potential (VEP)--were recorded in 51 cases of traumatic intracranial hemorrhage within 3 days after injury. In order to assess these EPs, five EP grades were constructed, from normal, Grade I, to highly abnormal, Grade V. Furthermore, an EP pattern classification was devised to integrate the respective EP grades. Namely, PA, consisting of all three EPs within Grades I-III; PB, composed of one type of EP or both ABR and VEP at Grades IV and V; PC, consisting of both SEP and VEP at Grades IV and V; PD, comprising both ABR and SEP at Grades IV and V; and PE, covering all three EPs at Grades IV and V. PA signifies "no severe damage," PB, "localized damage," PC, "severe cerebral damage," PD, "severe brainstem damage," and PE, "severe diffuse damage." The results when compared with computed tomography (CT) findings were as follows: 1) The size of hematoma correlated with the SEP grade in 16 cases of acute epidural hematoma; a hematoma diameter of 17.5 mm was the threshold value at which SEP abnormalities developed. Eleven patients who underwent surgical removal of the hematoma showed "no severe damage," and the outcome was good. 2) In 13 cases of acute subdural hematoma, six cases revealed "severe cerebral damage" or "severe diffuse damage." In such cases, the degree of damage was not related to the hematoma size, and the outcome was very poor. 3) In 13 cases of a solitary contusional hemorrhage, only one case revealed "severe diffuse damage" and subsequently died.(ABSTRACT TRUNCATED AT 250 WORDS)     

Urography versus DMSA scan in children with vesicoureteric reflux

Following the diagnosis of primary vesicoureteric reflux, identified as part of the investigation of urinary tract infection, 299 refluxing kidneys in 202 children (aged 0–14 years) were prospectively evaluated using intravenous urography (IVU) and the DMSA renal scan at least 4 weeks after urine infection. There was 88% concordance between IVU and the DMSA scan, but in 12% there were discrepancies manifested in 37 kidneys from 31 children. Thirty-four kidneys were normal on IVU but showed scars of reflux nephropathy (RN) on the technetium 99m-dimercaptosuccinic acid (DMSA) renal scan; 4 of these (2 infants and 2 pre-school children) had severe generalized changes on scanning. Three kidneys were normal of DMSA scan and, although abnormal on initial IVU, were considered to be normal when this was repeated. During a followup period of 5 years an annual DMSA was undertaken in 194 patients and the renal scars remained unchanged in all except 1 child. The IVU was repeated 1–3 years after the initial study in 31 children in which the results of the first imaging did not agree. In 28 patients (34 kidneys) in which the initial IVU was normal but the DMSA abnormal, IVU evidence of scarring emerged in 30 of 34 kidneys, including the 4 patients with severe generalized damage on the DMSA. We conclude that abnormalities detected by the DMSA scan may precede the radiological findings, especially in young children. Even severe RN can be established in kidneys that appear normal on the IVU.     

Evaluation of brain-stem dysfunction following severe fluid-percussion head injury to the cat

The degree of brain-stem dysfunction associated with high-level fluid-percussion injury (3.0 to 3.8 atm) was investigated in anesthetized cats. Measurements were made of the animals' intracranial pressure (ICP) pressure-volume index (PVI), far-field brain-stem auditory evoked responses (BAER's), and cerebral blood flow (CBF). The animals were classified into two groups based on the severity of neuropathological damage to the brain stem after trauma: Group 1 had mild intraparenchymal and subarachnoid hemorrhages and Group 2 had severe intraparenchymal and subarachnoid hemorrhages. The ICP values in Group 1 were insignificantly lower than those in Group 2, while the PVI values in Group 2 were clearly lower (p less than 0.05). Immediately after the injury, peaks II, III, and IV of the BAER's demonstrated a transitory and marked suppression. One Group 1 and two Group 2 animals showed the disappearance of peak V. In Group 1, the latencies of peak II, III, and IV gradually increased until 60 to 150 minutes postinjury, then returned to 95% of baseline value at 8 hours; however, the animals in Group 2 showed poor recovery of latencies. Two hours after brain injury, the CBF decreased to 40% of the preinjury measurement in both groups (p less than 0.001). In contrast to Group 2, the CBF in Group 1 returned to 86.8% of the preinjury measurement by 8 hours following the injury. Changes in PVI, BAER, and CBF correlated well with the degree of brain-stem injury following severe head injury. These data indicate that high-level fluid-percussion injury (greater than 3.0 atm) is predominantly a model of brain-stem injury.     

Clinical study of cortical and brainstem evoked potentials in head injury

Three types of evoked potentials (EPs) auditory brainstem response (ABR), somatosensory evoked potential (SEP), and visual evoked potential (VEP) were recorded among 100 cases of head injuries within three days after the trauma had occurred. In order to assess these EPs, the normal wave patterns of 20 healthy subjects were used for comparison. For indices, wave I, III and V were used for ABR, N1, N2 and N3 for SEP, and N70, P100 and N125 for VEP. On this basis, five EP grades were constructed, from normal (grade I) to highly abnormal (grade V). Furthermore, an EP pattern classification was devised to integrate the respective EP grade. Namely, pattern A (PA), consisting of grade (G). I-III of the 3 types of EP; PB, composed of one type of EP or both ABR and VEP at G. IV-V; PC, consisting of both SEP and VEP at G. IV-V; PD, comprising both ABR and SEP at G. IV-V; and PE, covering all three types EPs at G. IV-V. In this EP pattern classification, PA signifies no severe damage, PB localized damage, PC severe cerebral damage, PD severe brainstem damage, PE severe diffuse damage. The significance was studied for an understanding of the pathological state, and for making a prognosis. The following conclusions were reached. 1. In severe head trauma, primary brainstem damage is very rare, and in cases where brainstem damage is shown, it is accompanied by extensive cerebral damage. To assess the pathological state of such primary cerebral damage EP in the acute stage is useful, and by performing further EP, successively, it becomes also possible to evaluate the secondary cerebral damage.(ABSTRACT TRUNCATED AT 250 WORDS)     

The effect of common origin of the carotid arteries in neurologic outcome after neonatal ECMO

Background

Common origin of the carotid arteries (COCA) is a normal anatomic variant reported to occur in approximately 11% of the general population. The objective of this study was to determine whether this variant places venoarterial extracorporeal membrane oxygenation (ECMO) patients at a higher risk for adverse neurologic sequelae owing to potential occlusion of both carotid arteries by the arterial cannula.

Methods

The authors reviewed clinical records and echocardiograms of the initial 220 ECMO patients at their institution. Aortic arch morphology was determined by a pediatric cardiologist blinded to all other data. After exclusion of predetermined patients, 131 patients were divided into 2 groups: those with separate origin of the carotid arteries (n = 111) and those with COCA (n = 20). The neurologic outcome variables studied included the results of magnetic resonance imaging (MRI); computed tomography (CT); electroencephalogram (EEG); brainstem auditory-evoked response (BAER), head ultrasound scan, and Bayley Scales of Infant Development reported as Psychomotor Developmental Index (PDI) and Mental Developmental Index (MDI).

Results

COCA had no predictive value in determining PDI and MDI outcomes and no significance in predicting an increased risk of adverse neurologic sequelae based on MRI, CT, EEG, BAER, or head ultrasound scan.

Conclusions

This study confirms that COCA is a common aortic arch variant (15%, n = 20 of 131) and that this variant does not appear to increase the risk of neurologic injury in infants undergoing venoarterial ECMO.     

Long-term followup of initial Ta grade 1 transitional cell carcinoma of the bladder

PURPOSE: We evaluate the long-term outcome of initial Ta grade 1 transitional cell carcinoma. MATERIALS AND METHODS: A total of 152 patients with initial Ta grade 1 bladder tumor were followed for a mean of 76 months (range 6 to 241). Recurrence was defined as positive findings on cystoscopy or biopsy. Progression was defined as an increase in tumor grade or stage. RESULTS: Tumor recurrence in 83 of 152 patients (55%) was noted within 12 months of followup in 38 patients (46%), between 12 and 24 in 11 (13%), and between 24 and 60 in 22 (27%). A significant number of recurrences (12, 14%) were diagnosed more than 60 months after the first tumor. Of 83 patients with recurrence 31 (37%) had progression, including 21 to grade 2 and 2 to grade 3 disease. Carcinoma in situ was diagnosed in 3 patients and 5 had muscle invasive disease. Progression occurred more than 24 months after initial diagnosis in 20 patients and more than 60 months after first tumor event (2 had carcinoma in situ and 2 had muscle invasive disease) in 12. CONCLUSIONS: Ta grade 1 bladder transitional cell carcinomas have a high recurrence rate and progression is not uncommon. These findings warrant close long-term followup, even when in some settings the trend is to discontinue followup after 5 years without any abnormal findings.     

Epidermoid cyst of the fourth ventricle

The case of a 52-year-old patient with a fourth ventricle epidermoid is reported. The initial presentation included long-standing headaches, progressive anomalies of gait and slight impairment of mentation. CT showed a hypodense mass enhancing peripherally after contrast infusion. Brain auditory evoked responses (BAER) showed asymmetric increased latencies. At operation, total removal of an extensive fourth ventricle epidermoid was achieved. A delayed meningitis occurred postoperatively. Physical examination was normal at the 2 year follow-up and BAER were improved. The etiological and clinical features of fourth ventricular epidermoids are briefly reviewed. The diagnostic value of CT is emphasised but the possibility of CT-dense epidermoid cysts deserves a special mention. Total removal of the neoplasm is the theoretical aim of operative treatment, but this purpose may be harmful when the ventricular floor is involved by the capsule.     

Residual challenges after healing of congenital pseudarthrosis in the tibia

The purpose of the current study was to evaluate the clinical results of the Ilizarov bone transport method in the treatment of congenital pseudarthrosis in the tibia. In seven patients operated on between 2.6 and 7.8 years of age, primary healing of the pseudarthrosis was achieved in all patients (after additional bone grafting in two patients). Within a followup of 6 to 8 years, major complications occurred in all patients. Five refractures occurred, and in one patient the refracture did not heal. At the last followup, axial deformities and an abnormal malalignment test with lateral mechanical axis deviation of 10 mm or greater was found in all patients. Three patients had leg length inequality of 20 mm or more. The Ilizarov bone transport method is useful in achieving primary healing in congenital pseudarthrosis of the tibia, but residual challenges with secondary reconstructive surgery caused by refracture and postoperative deformities must be expected.     

Long-term results of intraoperative balloon dilatation

A review was conducted of 61 patients who underwent intraoperative balloon dilatation over the past five years. Of the 62 dilatations in this patient group, 80% were performed in conjunction with a reconstructive procedure, and 20% were performed as a primary procedure. Dilatations were performed with the linear extrusion balloon catheter. A 94% rate of followup was achieved, with a mean followup of 16.3 months (range 1-60 months). Life table analysis reveals a 95% initial success rate decreasing to an 81% patency rate by the end of the fifth year for iliac dilatations, a 97% initial and 58% five-year patency rate for superficial femoral dilatations, and an 86% initial and 37% five-year patency rate for popliteal dilatations. 21.3% of the patients died during the followup period. No deaths occurred as a result of intraoperative angioplasty. One arterial rupture occurred, requiring a bypass graft at the same surgery. We conclude that intraoperative balloon dilatation in an adjunctive setting may offer clinical benefits to vascular patients while requiring little additional operative time.     

Total condylar knee arthroplasty: a long-term followup.

Between July 1977 and December 1983, 80 patients underwent 120 arthroplasties using a total condylar knee prostheses. Forty-one patients (68 knees) died and 13 patients were lost to followup. Twenty-six patients with 34 total condylar replacements were available for clinical followup. During the followup, 10 knees in nine patients (8.3%) from the overall 80 patients (120 knees) underwent revision; three (four knees) for aseptic loosening, one for periprosthetic fracture, three for infection, and two patients underwent revision for pain. Three revisions (three patients) occurred in the group of 26 patients available for followup. The average age of this group of patients at followup was 78 years (range, 53-94 years). There were 10 men and 16 women. Considering the high mean age of the patients in the series and patients' overall health status, the clinical results were extremely good. Kaplan-Meier analysis showed a survivorship of 91% at 23 years followup, considering revision as an end point. Although there have been several changes in total knee replacement designs, materials, and implantation techniques, the long-term outcome of the original total condylar knee prosthesis is excellent.     

Impotence following pelvic fracture

A group of 42 men (mean age, 26.7 years) with pelvic fractures as the result of motor vehicle accidents were evaluated for impotence 48 hours after injury. Hormone levels were normal in all patients tested. One half (21/42) of the patients had abnormal penile:brachial arterial ratios. Of this group, 13/21 had abnormal bulbocavernosus reflex (BCR): four patients were paraplegic and nine had urethral injuries. Followup of available patients to 20 months reflects persistent impotence in those who experienced vasculogenic trauma. Only 2/21 patients with normal tests (vascular, hormonal, neurologic) complain of impotence (followup at 23 months); one of these patients is in litigation.     

The John Charnley Award: Redefining the Natural History of Osteoarthritis in Patients With Hip Dysplasia and Impingement

Background

Structural hip deformities including developmental dysplasia of the hip (DDH) and femoroacetabular impingement (FAI) are thought to predispose patients to degenerative joint changes. However, the natural history of these malformations is not clearly delineated.

Questions/purposes

(1) Among patients undergoing unilateral THA who have a contralateral hip without any radiographic evidence of hip disease, what is the natural history and progression of osteoarthritis in the native hip based on morphological characteristics? (2) Among patients undergoing unilateral THA who have a contralateral hip without any radiographic evidence of hip disease, what are the radiographic parameters that predict differential rates of degenerative change?

Methods

We identified every patient 55 years of age or younger at our institution who received unilateral primary THA from 1980 to 1989 (n = 722 patients). Preoperative radiographs were reviewed on the contralateral hip and only hips with Tönnis Grade 0 degenerative change that had minimum 10-year radiographic followup were included. A total of 172 patients met all eligibility criteria with the following structural diagnoses: 48 DDH, 74 FAI, and 40 normal morphology, and an additional 6% (10 of the 172 patients) met all eligibility criteria but were lost to followup before the 10-year minimum. Mean age at the time of study inclusion was 47 years (range, 18–55 years), and 56% (91 of 162) of the patients in this study were female. Mean followup was 20 years (range, 10–35 years). Radiographic metrics, in conjunction with the review of two experienced arthroplasty surgeons, determined the structural hip diagnosis as DDH, FAI, or normal morphology. Every available followup AP radiograph was reviewed to determine progression from Tönnis Grade 0 to 3 until the time of last followup or operative intervention with THA. Survivorship was analyzed by Kaplan-Meier methodology, hazard ratios, and multistate modeling. Thirty-five patients eventually underwent THA: 16 (33%) DDH, 13 (18%) FAI, and six (15%) normal morphology.

Results

Degenerative change was most rapid in patients with DDH followed by FAI and normal morphology. Among patients who recently developed Tönnis 1 degenerative change, the probability of undergoing THA in 10 years based on hip morphology was approximately one in three for DDH and one in five for both FAI and normal morphology hips, whereas the approximate probability at 20 years was two in three for DDH and one in two for both FAI and normal morphology hips. The likelihood of radiographic degeneration was increased in patients with the following findings: femoral head lateralization > 8 mm, femoral head extrusion index > 0.20, acetabular depth-to-width index < 0.30, lateral center-edge angle < 25°, and Tönnis angle > 8°.

Conclusions

Degenerative change occurred earliest in patients with DDH, whereas the natural history of patients with FAI was quite similar to structurally normal hips. However, patients with cam deformities and concomitant acetabular dysplasia developed osteoarthritis more rapidly. Although the results of this study cannot be directly correlated to highly active patients with FAI, these findings suggest that correction of FAI to a normal morphology may only minimally impact the natural history, especially if intervention takes place beyond Tönnis 0. Analysis of radiographic parameters showed that incremental changes toward dysplastic morphology increase the risk of degenerative change.

Level of Evidence

Level III, prognostic study.

     

Longitudinal followup study of ultrasonography in congenital muscular torticollis

High-resolution ultrasonography was used to examine affected sternocleidomastoid muscles in patients with congenital muscular torticollis at different times. Thirty-one female and 42 male patients were recruited and classified as having one of four types of fibrosis based on the sonograms. Compared with initial assessment, 22 (95.6%) patients with Type I fibrosis and 22 (57.9%) patients with Type II fibrosis had a change in classification at the end of the study. Among the patients with Type I fibrosis, the classification of one patient was changed to Type III fibrosis, the classifications of two patients were changed to normal muscle, and the classifications of the other patients were changed to Type II fibrosis. For patients with Type II fibrosis, the classifications of two patients were changed to Type III fibrosis, the classifications of three patients were changed to Type IV fibrosis, and the classifications of the other patients were changed to normal muscle. No changes in classification of patients with Types III and IV fibrosis occurred during followup. Patients with Type IV fibrosis had a significantly high incidence of surgical intervention. Congenital muscular torticollis is a dynamic disease. Ultrasonography can be valuable in observing the alteration. Aggressive management may be necessary for patients with Type IV fibrosis.     

Design,operative technique and ten-year results of the Hermes™ patellofemoral arthroplasty

Purpose

Recently, increased interest has developed for patellofemoral arthroplasty as treatment for isolated patellofemoral arthritis. However, there are very few reports of the experience with the modern generation of patellofemoral arthroplasties. The new patellofemoral arthroplasty Hermes design is described. The design and technique of insertion are detailed.

Methods

The indications were isolated patellofemoral disease with advanced arthritic damage. Ten-year followup is available for treatment of 70 knees. Postoperative radiographs of patients were assessed for Oxford deterioration and maltracking of the patella. Tracking was categorised as follows: normal tracking, patellar subluxation, patellar dislocation.

Results

There were no late complications attributable to the arthroplasty. Disease progression in the tibiofemoral joint occurred in five patients requiring revision in three of these patients. Persistent anterior knee pain was recorded in four knees. The long-term results using this new design were better than those in the literature that described earlier designs, especially concerning malalignment. Only four knees in four patients had slight lateral patellar subluxation.

Conclusions

This implant offers a reasonable alternative to total knee replacement in patients with isolated patellofemoral disease.     

Early morphologic and spectroscopic magnetic resonance in severe traumatic brain injuries can detect "invisible brain stem damage" and predict "vegetative states"

A precise evaluation of the brain damage in the first days of severe traumatic brain injured (TBI) patients is still uncertain despite numerous available cerebral evaluation methods and imaging. In 5-10% of severe TBI patients, clinicians remain concerned with prolonged coma and long-term marked cognitive impairment unexplained by normal morphological T2 star, flair, and diffusion magnetic resonance imaging (MRI). For this reason, we prospectively assessed the potential value of magnetic resonance spectroscopy (MRS) of the brain stem to evaluate the functionality of the consciousness areas. Forty consecutive patients with severe TBI were included. Single voxel proton MRS of the brain stem and morphological MRI of the whole brain were performed at day 17.5 +/- 6.4. Disability Rating Scale and Glasgow Outcome Scale (GOS) were evaluated at 18 months posttrauma. MRS appeared to be a reliable tool in the exploration of brainstem metabolism in TBI. Three different spectra were observed (normal, cholinergic reaction, or neuronal damage) allowing an evaluation of functional damage. MRS disturbances were not correlated with anatomical MRI lesions suggesting that the two techniques are strongly complementarity. In two GOS 2 vegetative patients with normal morphological MRI, MRS detected severe functional damage of the brainstem (NAA/Cr < 1.50) that was described as "invisible brain stem damage." MRI and MRS taken separately could not distinguish patients GOS 3 (n = 7) from GOS 1-2 (n = 11) and GOS 4-5 (n = 20). However, a principal component analysis of combined MRI and MRS data enabled a clear-cut separation between GOS 1-2, GOS 3, and GOS 4-5 patients with no overlap between groups. This study showed that combined MRI and MRS provide a reliable evaluation of patients presenting in deep coma, specially when there are insufficient MRI lesions of the consciousness pathways to explain their status. In the first few days post-trauma metabolic (brainstem spectroscopy) and morphological (T2 star and Flair) MRI studies can predict the long-term neurological outcome, especially the persistent vegetative states and minimally conscious state.     

Microvascular decompression for hemifacial spasm: long-term results from 114 operations performed without neurophysiological monitoring

OBJECT: Microvascular decompression (MVD) of the facial nerve is an effective treatment for hemifacial spasm (HFS), but the procedure is associated with a significant risk of complications such as hearing loss and facial weakness. Many surgeons advocate the use of intraoperative brainstem auditory evoked response (BAER) monitoring in an attempt to improve surgical outcomes. The authors critically assessed a large series of patients with HFS who underwent MVD without neurophysiological monitoring. METHODS: The authors retrospectively identified 114 consecutive patients, with a history of HFS and without a history of HFS surgery, in whom MVD was performed by a single surgeon without the use of neurophysiological monitoring. Postoperative outcomes were determined by reviewing records and through telephone interviews. At least 1 year of postoperative follow-up data were available for 91 of the 114 patients, and the median follow-up duration in all cases was 8 years (range 3 months-23 years). A Kaplan-Meier analysis showed that 86% of the patients were spasm free at 10 years postoperatively. RESULTS: There were no surgical deaths or major deficits, and complications included 1 case of postoperative deafness, 1 of permanent subtotal hearing loss, and 10 of delayed facial palsy, 2 of which did not completely resolve at last follow-up. The outcomes, rates of hearing loss, and other complications compared well with those reported in studies in which investigators used intraoperative monitoring. CONCLUSIONS: The results suggest that MVD without neurophysiological monitoring is a safe and effective treatment option in patients with HFS. Although BAER monitoring may be a valuable adjunct to surgery at centers experienced with the modality, the absence of intraoperative monitoring should not prevent neurosurgeons from performing MVD in patients with HFS.