Multi-omics analyses of choroid plexus carcinoma cell lines reveal potential targetable pathways and alterations.

PURPOSE: Choroid plexus carcinomas (CPCs) are extremely rare brain tumors and carry a dismal prognosis. Treatment options are limited and there is an urgent need to develop models to further research. In the present study, we established two CPC cell lines and performed multi-omics analyses. These cell lines serve as valuable models to propose new treatments in these rare but deadly brain tumors. METHODS: Multi-omic profiling including, (i) methylation array (EPIC 850 K), (ii) whole genome sequencing (WGS), (iii) CANCERPLEX cancer genome panel testing, (iv) RNA sequencing (RNA-seq), and (v) proteomics analyses were performed in CCHE-45 and NGT131 cell lines. RESULTS: Both cell lines were classified as methylation class B. Both harbored pathogenic TP53 point mutations; CCHE-45 additionally displayed TP53 loss. Furthermore, alterations of the NOTCH and WNT pathways were also detected in both cell lines. Two protein-coding gene fusions, BZW2-URGCP, and CTTNBP2-ERBB4, mutations of two oncodrivers, GBP-4 and KRTAP-12-2, and several copy number alterations were observed in CCHE-45, but not NGT131. Transcriptome and proteome analysis identified shared and unique signatures, suggesting that variability in choroid plexus carcinoma tumors may exist. The discovered difference's importance and implications highlight the possible diversity of choroid plexus carcinoma and call for additional research to fully understand disease pathogenesis. CONCLUSION: Multi-omics analyses revealed that the two choroid plexus carcinoma cell lines shared TP53 mutations and other common pathway alterations and activation of NOTCH and WNT pathways. Noticeable differences were also observed. These cell lines can serve as valuable models to propose new treatments in these rare but deadly brain tumors.

Reliable detection of genetic alterations in cyst fluid DNA for the diagnosis of brain tumors.

PURPOSE: Liquid biopsy of cyst fluid in brain tumors has not been extensively studied to date. The present study was performed to see whether diagnostic genetic alterations found in brain tumor tissue DNA could also be detected in cell-free DNA (cfDNA) of cyst fluid in cystic brain tumors. METHODS: Cyst fluid was obtained from 22 patients undergoing surgery for a cystic brain tumor with confirmed genetic alterations in tumor DNA. Pathological diagnoses based on WHO 2021 classification and diagnostic alterations in the tumor DNA, such as IDH1 R132H and TERT promoter mutation for oligodendrogliomas, were detected by Sanger sequencing. The same alterations were analyzed by both droplet digital PCR (ddPCR) and Sanger sequencing in cyst fluid cfDNA. Additionally, multiplex ligation-dependent probe amplification (MLPA) assays were performed to assess 1p/19q status, presence of CDKN2A loss, PTEN loss and EGFR amplification, to assess whether differentiating between astrocytomas and oligodendrogliomas and grading is possible from cyst fluid cfDNA. RESULTS: Twenty-five genetic alterations were found in 22 tumor samples. All (100%) alterations were detected in cyst fluid cfDNA by ddPCR. Twenty of the 25 (80%) alterations were also detected by Sanger sequencing of cyst fluid cfDNA. Variant allele frequency (VAF) in cyst fluid cfDNA was comparable to that of tumor DNA (R = 0.62, Pearson's correlation). MLPA was feasible in 11 out of 17 (65%) diffuse gliomas, with close correlation of results between tumor DNA and cyst fluid cfDNA. CONCLUSION: Cell-free DNA obtained from cyst fluid in cystic brain tumors is a reliable alternative to tumor DNA when diagnosing brain tumors.

Visualization of cortical neoangiogenesis after combined revascularization surgery in moyamoya disease using silent MRA.

PURPOSE: To investigate postsurgical indirect cortical neoangiogenesis in patients with moyamoya disease (MMD) using silent magnetic resonance angiography (MRA). METHODS: We studied 44 patients with MMD (63 hemispheres) who were previously revascularized with combined bypass surgery (23 and 40 hemispheres in pediatric and adult patients, respectively). They underwent follow-up for postoperative bypass patency using time-of-flight (TOF)-MRA and silent MRA between January 2022 and December 2023. The mean duration from surgery to MRA was 8.5 years (range, 1.2-22.3 years). Two observers independently rated the revascularization as follows: 0 (near-complete signal loss or no signal); 1, poor (slightly visible donor arteries); 2, good (acceptable revascularization around the brain surface); and 3, excellent (good quality of revascularization with perfusion from the cortical surface into the middle cerebral artery). RESULTS: Silent MRA visualized indirect bypass significantly better than TOF-MRA (2.6 ± 0.7 and 1.4 ± 0.8) (P < 0.01). In silent MRA, the mean score of indirect bypass was significantly higher than that of direct bypass (2.6 ± 0.7 and 1.7 ± 1.0; P < 0.01) and indicated good indirect bypass development in both children and adults (91.3% and 85.0%; score ≥ 2). Children exhibited a higher rate of excellent indirect bypass patency than adults (73.9% and 55.0%; score 3). Poor bypass development in indirect bypass (8 hemispheres, mean age: 35.5 ± 17.5 years, mean follow-up period: 11.3 years) was significantly observed in male patients (P < 0.01). CONCLUSION: Silent MRA enables better precision in postsurgical visualization of indirect cortical neoangiogenesis during long-term follow-up and reveals indirect bypass development even in adult patients.

Preoperative interactive virtual simulation applying three-dimensional multifusion images using a haptic device for lumbosacral lipoma.

PURPOSE: Untethering surgery for lumbosacral lipoma is a preventive procedure, and avoidance of complications and good long-term outcomes are required. We introduced presurgical interactive virtual simulation (IVS) applying three-dimensional multifusion images using a haptic device aimed at improving operative outcomes. METHODS: Fourteen patients with newly diagnosed lumbosacral lipoma were recruited and underwent preoperative IVS. The median age at surgery was 8 months. A three-dimensional image analysis system was used to extract and fuse structures necessary for surgery, such as the lipoma, spinal cord and skin, from CT and MRI, and create three-dimensional multifusion images. The created images were individually converted to standard triangulated language format and loaded onto a workstation (Geomagic freeform™) that could be freely transformed, and the laminectomy range and lipoma extraction procedure were examined. Presurgical IVS was performed, and the actual surgery was performed. RESULTS: The disease types were dorsal, caudal, lipomyelomeningocele, transitional, and filum in 5, 5, 2, 1, and 1 patients, respectively. The surgical procedure and extent of the laminectomy were as planned for all patients. Resection of the lipomas tended to be less than expected preoperatively because of positive reactions on intraoperative monitoring. No postoperative complications were observed. The median postoperative follow-up period was 29 months, and there were no reoperations during the observation period. CONCLUSIONS: Although there are various types of lumbosacral lipoma, surgery can be safely performed by performing presurgical IVS. The short-term course is good; however, long-term follow-up is necessary for the appearance of neurological symptoms associated with growth and re-tethering.

[Interactive Virtual Simulation with Haptics for Neurosurgery].

We established a unique pre-surgical simulation method by applying interactive virtual simulation(IVS)using multi-fusion three-dimensional imaging data, presenting high-quality visualization of microsurgical anatomies. Our IVS provided a realistic environment for imitating surgical manipulations, such as dissecting bones, retracting brain tissues, and removing tumors, with tactile and kinesthetic sensations delivered through a specific haptic device. The great advantage of our IVS was in deciding the most appropriate craniotomy and bone resection to create the optimal surgical window and obtain the best working space with a thorough understanding of the lesion-bone relationship. Particularly for skull-base tumors, tailoring the procedures to individual patients for craniotomy and bone resection was sufficiently achieved using our IVS. In cases of large skull base meningiomas, our IVS was also helpful preoperatively regarding tumors, as several compartments were achievable in every potentially usable surgical direction. Additionally, the non-risky realistic microsurgical environments of the IVS provided improvement in the microsurgical senses and skills of young trainees through the repetition of surgical tasks. Finally, our presurgical IVS simulation method provided a realistic environment for practicing microsurgical procedures virtually and enabled us to ascertain the complex microsurgical anatomy, determine optimal surgical strategies, and efficiently educate neurosurgical trainees.

[Intraoperative Monitoring During Microvascular Decompression].

During microvascular decompression(MVD)for hemifacial spasm(HFS), trigeminal neuralgia(TN), and glossopharyngeal neuralgia(GPN), brainstem auditory-evoked potential monitoring is widely used to preserve hearing function. In MVD for HFS, abnormal muscle response monitoring is useful for identifying the offending vessels compressing the facial nerve and confirming the completion of decompression intraoperatively. The amplitude of facial motor-evoked potential by transcranial electrical stimulation in the orbicularis oculi muscle is reported to decrease after completing MVD. The Z-L response(ZLR)probably confirms the true offending vessels by stimulating the culprit vessels; then, the ZLR could disappear after decompressing the offending vessels away from the compression sites. Spontaneous electromyographic activities obtained from the mentalis muscles by injection of saline into the facial nerve reportedly decreased after MVD compared with those before MVD. In MVD for the GPN, glossopharyngeal motor-evoked potential by transcranial electrical stimulation is used to preserve swallowing function and not to assess the completion of MVD. Because MVD for both the TN and GPN can result in normalization of the hyperactivity of the sensory nerve, it may be difficult to develop any monitoring to confirm the completion of MVD during surgery.

Elucidating the multiple genetic alterations involved in the malignant transformation of a KRAS mutant neurenteric cyst. A case report.

Neurenteric cyst (NC) shows benign histopathology and rarely demonstrate malignant transformation. We herein describe a case of NC that exhibited malignant transformation. A 65-year-old female presented with gait disturbance due to compression by a cystic mass on the dorsal surface of the medulla oblongata. Partial resection was performed twice, leading to improvement of her symptoms. Two years after the second surgery, gadolinium-perfused T1-weighted magnetic resonance imaging revealed an invasive lesion with contrast enhancement at the trigone of the left lateral ventricle for which partial resection followed by radiotherapy was performed. However, mass regrowth was observed, with the patient eventually succumbing to her disease 11 months after her third surgery. Histopathological analyses of the first and second surgical specimens identified pseudostratified cuboidal epithelial cells, with no nuclear or cellular atypia resembling gastrointestinal mucosa, lining the inner surface of the cystic wall. Based on these findings the lesion was diagnosed as NC. The third surgical specimen exhibited apparent malignant features of the epithelial cells with elongated and hyperchromatic nuclei, several mitotic figures, small necrotic foci, and a patternless or sheet-like arrangement. Based on these findings, the lesion was diagnosed as NC with malignant transformation. Next-generation sequencing revealed KRAS p.G12D mutation in all specimens. Additionally, the third surgical specimen harbored the following 12 de novo gene alterations: ARID1A loss, BAP1 p.F170L, CDKN1B loss, CDKN2A loss, CDKN2B loss, FLCN loss, PTCH1 loss, PTEN loss, PTPRD loss, SUFU loss, TP53 loss, and TSC1 loss. The aforementioned results suggest that KRAS mutation is associated with the development of the NC, and that the additional gene alterations contribute to malignant transformation of the NC.

Endovascular treatment of an infectious aneurysm using the selective provocative test and transcranial motor evoked potential monitoring under general anesthesia: a case report.

The selective provocative test (SPT) under local anesthesia aids in protecting against ischemic complications during endovascular treatment. However, the use of this test under general anesthesia is not well described. Herein, we present a case of a 51-year-old man with a ruptured fusiform aneurysm in the middle cerebral artery M4 segment, which was thought to possibly supply the motor cortex. Internal trapping of the affected vessel and aneurysm by endovascular intervention was successfully performed after SPT using transcranial motor evoked potential (MEP) monitoring under general anesthesia. Transcranial MEP is suitable for neurological assessment during SPT under general anesthesia.

[Intraoperative Neuromonitoring for Skull Base Surgery].

Intraoperative neuromonitoring techniques can be used to evaluate neural functions during surgical procedures. For removal of tumors in the skull base region, we perform them for both structural mapping of the compressed cranial nerves and continuous monitoring of their preservation. The goal is to eliminate the critical irreversible damage to the neurological structures and prevent postoperative neurologic deficits. Recording techniques have been developed and neuromonitoring equipment used in the operation room with the intravenous anesthesia technique. For skull base surgery, in particular, the neuromonitoring contains motor evoked potential(MEP), brainstem auditory evoked potential(BAEP), visual evoked potential(VEP), and others. We believe that the appropriate recording and interpretation of these data can greatly improve the surgical outcomes of tumor removal and prevent postoperative neurologic deficits.

Intraoperative findings of abnormal muscle response for hemifacial spasm following botulinum neurotoxin treatment.

OBJECTIVE: This study aimed to investigate the effect of preoperative botulinum toxin (BTX) injection on intraoperative abnormal muscle response (AMR) in patients with hemifacial spasm (HFS). METHODS: A total of 104 patients (32 men, 72 women) who underwent microvascular decompression (MVD) for HFS were included in this study. A total of 62 patients without and 42 patients with preoperative BTX treatments were assigned to group A and group B, respectively. AMR recordings were obtained from the orbicularis oculi and mentalis muscles by stimulation of the marginal mandibular branch and zygomatic branch of the facial nerve, respectively. The intraoperative AMR monitoring findings and therapeutic effects were compared between groups A and B. RESULTS: The rates of the patients with unavailable AMRs recorded from the orbicularis oculi muscles in group B (38.1%) were significantly higher than those in group A (14.5%, p = 0.006). Moreover, in cases with over 4 times BTX injection, the recordings of AMR from the orbicularis oculi muscles were poorer than the cases with less BTX injection (p = 0.001). There were no significant differences in the rates of the patients with unavailable AMRs recorded from the mentalis muscles between the two groups. There were no significant differences in the surgical results obtained between the two groups. CONCLUSIONS: Preoperative BTX injections should be less than 4 times to ensure effective AMR monitoring. MVD using AMR monitoring is useful for patients with HFS who were previously treated by BTX as well as those who were not treated.

Unilateral oculomotor nerve palsy caused by arterial compression accompanying subarachnoid hemorrhage: a case report.

Unilateral oculomotor nerve palsy, often caused by aneurysmal compression, is one of the decisive findings for confirming the site of a ruptured aneurysm. However, arterial compression can also cause unilateral oculomotor nerve palsy. Here, we present the case of a 59-year-old woman with a ruptured right internal carotid-posterior communicating artery aneurysm accompanied by contralateral oculomotor nerve palsy. The nerve was found to be compressed by the posterior cerebral artery and was isolated from the ruptured aneurysm. When confirming a ruptured aneurysm based on the evidence of unilateral oculomotor palsy, the arteries surrounding the nerve must be thoroughly assessed.

[Multinodular and Vacuolating Neuronal Tumor of the Cerebrum(MVNT)].

Multinodular and vacuolating neuronal tumors of the cerebrum(MVNTs)are rare brain tumors that were described first in 2013. MVNTs have been added to the World Health Organization Classification of Tumors of the Central Nervous System in 2016(2016WHO), although an MVNT is a clinical-pathological lesion with uncertain class assignment. It remains unclear whether MVNTs should be considered a true neoplasm or malformative lesion. Their prevalence and pathophysiology are unknown. MVNTs typically occur in adults, predominantly in the cerebral subcortical region, and are most frequently associated with seizures or seizure equivalents. MVMTs can also present incidentally without seizures. MVNTs have been reported to show highly suggestive imaging features, especially on MRI scans. MVNTs consist of small T2 and T2-FLAIR hyperintense nodules in subcortical and juxtacortical areas with rare or no post-contrast enhancement. Most MVNTs reported in the literature involve the supratentorial part of the brain. Recently, lesions exhibiting a remarkably similar pattern of imaging findings were described in the posterior fossa, which are referred to as multinodular and vacuolating posterior fossa of unknown significance(MV-PLUS). Both MVNT and MV-PLUS are considered "leave-me-alone" lesions because of the absence of malignancy criteria and the lack of evolutivity on follow-up MRI scans.

[Melanocytic Tumors].

Primary melanocytic neoplasms of the central nervous system(CNS)presumably arise from leptomeningeal melanocytes that are derived from the neural crest. Melanocytic neoplasms associated with neurocutaneous melanosis likely derive from melanocyte precursor cells that reach the CNS after somatic mutations, mostly, of the NRAS. They should be distinguished from other melanotic tumors involving the CNS, including metastatic melanoma and other primary tumors that undergo melanization, such as melanocytic schwannomas, medulloblastomas, paragangliomas, and various gliomas, because these lesions require different patient workups and therapy. Primary melanocytic neoplasms of the CNS that are diffuse and do not form macroscopic masses are called melanocytoses, whereas malignant diffuse or multifocal lesions are collectively called melanomatoses. Benign and intermediate-grade tumoral lesions are called melanocytomas. Discrete malignant tumors are called melanomas. CT and MRI of melanocytosis and melanomatosis show diffuse thickening and enhancement of the leptomeninges, often with focal or multifocal nodularity. Depending on the melanin content, diffuse and circumscribed melanocytic tumors of the CNS may show some characteristics on CT and MRI: iso- to hyperattenuation on CT and paramagnetic properties of melanin on MRI resulting in an isointense signal on T1WIs and iso- to hypointensity on T2WIs.

[Dysplastic Cerebellar Gangliocytoma(Lhermitte-Duclos Disease)].

Dysplastic cerebellar gangliocytoma or Lhermitte-Duclos disease(LDD)is a rare benign cerebellar lesion composed of dysplastic ganglion cells that conform to the existing cortical architecture. In this disease, the enlarged ganglion cells are predominantly located within the internal granular layer, and they thicken the cerebellar folia. The architecture of the affected cerebellar hemisphere with the enlarged cerebellar folia and the cystic changes, in some cases, present as "tiger-striped striations," a characteristic imaging finding that is not specific to LDD. This imaging feature may be observed in medulloblastoma and isolated cerebellar Rosai-Dorfman disease. This cerebellar lesion is a major central nervous system manifestation of Cowden syndrome, an autosomal dominant condition that causes various hamartomas and neoplasms. A molecular-based study estimated the prevalence of Cowden syndrome to be 1 case per 200,000. In a study involving 211 patients with Cowden syndrome, 32% developed LDD. LDD can be diagnosed in young children and older adults within the eighth decades of life. PTEN mutations have been identified in virtually all adult-onset LDDs, but not in childhood-onset cases.

Vascular Hyperintensity on Fluid-Attenuated Inversion Recovery Indicates the Severity of Hypoperfusion in Acute Stroke.

BACKGROUND AND AIM: Although fluid-attenuated inversion recovery vascular hyperintensities may be frequently seen in acute large-artery ischemic stroke, reports on their prognostic utility had been conflicting due to lack of quantitative evaluation of the perfusion status based on the signal intensity. We hypothesized that greater hyperintensity represents more severe hypoperfusion. METHODS: Overall, 27 patients with acute occlusion of the proximal middle cerebral artery were divided into 2 groups, based on their signal intensity in the insular segment of middle cerebral artery on the affected side, relative to that of the insular cortex: the low signal intensity group (hypo- or isointense signals, n = 12) and the high signal intensity group (hyperintense signals, n = 15). Using dynamic susceptibility contrast magnetic resonance imaging, we assessed the time of the maximum value of the residue function and mean transit time, in the entire middle cerebral artery cortical area and diffusion-weighted imaging-Alberta Stroke Program Early Computed Tomography Score regions, including the corona radiata. RESULTS: The high signal intensity group had significantly longer time of the maximum value of the residue function in all the diffusion-weighted imaging-Alberta Stroke Program Early Computed Tomography Score regions, except the M3 and M6 regions, and significantly longer mean transit time in the M1 and M4 regions. CONCLUSIONS: Quantitative analysis of the perfusion parameters revealed more severely compromised and widely disturbed perfusion status in the high signal intensity group than in the low signal intensity group.

[Endovascular Revascularization for Acute Ischemic Stroke Related to Blunt Carotid Injury:A Case Report].

Although blunt carotid artery injury is known as an important cause of ischemic stroke, the role of the endovascular treatment for acute ischemic stroke related to blunt carotid injuries remains unclear. We report the case of a patient with acute ischemic stroke secondary to blunt carotid artery injury who was treated with endovascular revascularization. A 46-year-old man suffered from sudden left-sided hemiparesis a day after a strike from a Japanese fencing staff on his right neck. 3D-CT angiography revealed tandem internal carotid artery occlusions of the cervical and C1 portions. We performed endovascular revascularization with carotid artery stenting and direct aspiration of the thrombus and achieved complete recanalization. The patient recovered almost completely. We conclude that endovascular revascularization should not be withheld from patients with acute ischemic stroke related to blunt carotid injury.

[Posterior Quadrantectomy for Infant with Refractory Epilepsy:A Case Report].

We present the case of an 11-month-old girl with linear nevus sebaceous syndrome who underwent posterior quadrantectomy(PQ)for intractable epilepsy due to cortical dysplasia extending from the temporal, parietal, and occipital lobes in the right hemisphere. Epileptic spasms started at 4 months after birth, and the frequency of her seizures gradually increased to 10 episodes per day. Electroencephalograms in the interictal periods showed hypsarrhythmia. Magnetic resonance imaging(MRI)suggested cortical dysplasia in the right temporal, parietal, and occipital lobes. Ictal single-photon emission computed tomography revealed increased cerebral blood flow in similar areas as the cortical dysplasia suggested on MRI. Several antiepileptic drugs were administered to control the epileptic spasms, without success. In addition, her developmental delay gradually became evident. Because the epileptic foci extended into the posterior region of the right hemisphere, we did not execute a focused resection, but performed a PQ. The epileptic spasms completely disappeared after surgery and her developmental delay gradually improved. Early surgical intervention via PQ is useful in patients with drug-resistant epilepsy in whom the epileptic foci have extended into the temporal, parietal, and occipital lobes. This intervention not only controls intractable seizures but also helps to facilitate normal development.

Polysomnography as an indicator for cervicomedullary decompression to treat foramen magnum stenosis in achondroplasia.

OBJECTIVE: Management of cervicomedullary compression due to foramen magnum stenosis in achondroplasia remains controversial, especially for patients with no symptoms or mild symptoms. We examined the effectiveness of polysomnography (PSG) as an indicator for cervicomedullary decompression treatment. METHODS: We retrospectively reviewed nine achondroplasia cases (mean age 1 year and 9 months) treated from 2008 to 2015. All patients were examined by PSG, magnetic resonance imaging (MRI), and otolaryngeal fibroscopy. We analyzed demographic data, clinical presentation, degree and type of respiratory impairment, severity of foramen magnum stenosis and concomitant cervicomedullary compression, treatment (conservative or surgical), and clinical outcome. RESULTS: Eight of nine patients presented with no severe symptoms in the daytime. However, MRI revealed four severe, four moderate, and one mild case of cervicomedullary compression, and PSG demonstrated severe sleep apnea in four cases and moderate sleep apnea in five cases. All sleep apnea cases were obstructive or obstructive-dominant. Fibroscopy revealed no upper airway stenosis in six cases and mild stenosis in three cases. Four patients who had severe sleep-related respiratory disturbance on PSG and severe or moderate cervicomedullary compression were treated by cervicomedullary decompression. Three of these patients demonstrated improved sleep respiration soon after surgery, while one required temporary tracheostomy due to bilateral vocal cord paralysis caused by compression during intratracheal intubation. CONCLUSION: Polysomnography can be a useful indicator for cervicomedullary decompression surgery, especially in cases of seemingly asymptomatic achondroplasia with severe foramen magnum stenosis.

[Application of brain diffusion-weighted imaging performed using readout segmentation of long variable echo trains].

We report the preliminary use of the readout segmentation of long variable echo trains(RESOLVE)sequence, a novel magnetic resonance(MR)scanning technique based on a readout segmented echo planar imaging(EPI)strategy. RESOLVE enables high-resolution diffusion-weighted imaging(DWI)by minimizing susceptibility distortions and T2* blurring. The software for this sequence was provided by Siemens AG, Germany. Previously, we determined appropriate sequence parameters to obtain sufficiently high-resolution images through phantom studies. Then, we applied the sequence to some clinical cases with neurological disorders and analyzed the RESOLVE-DWI data with diffusion tensor imaging(DTI)techniques. In this article, we report clinical application of the RESOLVE sequence in two cases, one with cerebellar infarction and one with an intracranial epidermoid cyst. In both cases, RESOLVE-DWI clearly exposed structures that were obscured or severely distorted by artifacts on usual single-shot EPI-DWI. DTI analyses for RESOLVE-DWI data provided detailed information about fiber tracts and cranial nerves.

Importance of changes in abnormal muscle responses during microvascular decompression for hemifacial spasm.

Objective: To determine if compression sites of the facial nerve correlate with immediate postoperative outcomes in patients with hemifacial spasm (HFS), and if changes in the waveform of abnormal muscle response (AMR) during microvascular decompression (MVD) for HFS can predict the postoperative course. Methods: In this retrospective review, we evaluated 50 patients with HFS who underwent AMR monitoring during MVD. The ratios of amplitude and duration of AMR waveforms were computed by comparing baseline with final examinations. Vascular compression sites were categorized into four portions of the facial nerve. Postoperatively, we classified patients into two groups based on symptom relief as those whose symptoms disappeared immediately (DI group), and those whose symptoms disappeared gradually (DG group). Results: The compression sites significantly correlated with postoperative outcomes at discharge (p < 0.001) but not with outcomes after 6 months of MVD. Lower duration ratios of AMRs from the mentalis muscle were significantly associated with an increased chance of classification into the DI group based on the results of multivariate logistic regression analysis (p = 0.017). Conclusions: Relationship between compression sites and immediate outcomes could provide useful information to surgeons for predicting if symptoms will resolve over long term. Moreover, changes in AMRs recorded from the mentalis muscle could predict the postoperative course of HFS. Significance: These findings can help surgeons evaluate the changes in AMR amplitude and duration during MVD for HFS.