Utility of the Repetitive Nerve Stimulation Test and Needle EMG in the Trapezius Muscle for the Early Diagnosis of ALS.

OBJECTIVES: To document the utility of decremental responses in the repetitive nerve stimulation test (RNS) and spontaneous activities in needle electromyography (EMG) in the trapezius muscle for the diagnosis of amyotrophic lateral sclerosis. METHODS: Subjects were retrospectively identified from our EMG database. Cervical spondylosis was represented as a disease control group. We investigated the sensitivity and specificity of RNS and EMG in the trapezius muscle and those of diagnostic criteria including the Gold Coast criteria (GCC). RESULTS: We reviewed 120 patients with amyotrophic lateral sclerosis and 17 patients with cervical spondylosis. "RNS or EMG" achieved the highest sensitivity (85%). The specificity was the highest for RNS (94%). Addition of RNS of the deltoid muscle achieved 98% sensitivity in the upper-limb onset amyotrophic lateral sclerosis. The sensitivity of the GCC was very high (88%). CONCLUSIONS: Neurophysiological parameters investigated in this study having close to 100% specificities or sensitivities are useful as complements to the GCC.

Deep Brain Stimulation Leads to Long-term Improvement of Neuropathic Tremor due to Chronic Inflammatory Demyelinating Polyneuropathy: A Case Report.

Chronic inflammatory demyelinating polyneuropathy (CIDP) is a peripheral neuropathy caused by immune-mediated demyelination, causing tremors in 3.9%-58% of affected patients. This neuropathic tremor may persist after treatment and is known to be refractory to conventional medication. We present two cases of neuropathic tremor due to CIDP in which deep brain stimulation (DBS) over a long-term period led to marked improvement. Case 1: A 66-year-old woman presented with severe 2-3-Hz resting, postural, and kinetic tremors of both hands. The tremor was refractory to medication but improved well after bilateral VIM-DBS. However, 2 months after the procedure, the tremor worsened and was accompanied by sensory disturbance in the extremities. A diagnosis of CIDP was made, and treatment with corticosteroids and intravenous immunoglobulin achieved remission 6 months later. Although there was residual tremor after CIDP remission, it has been well controlled by DBS for the last 10 years. Case 2: A 56-year-old man presented with a 6-year history of CIDP after developing sensory dullness and tremors in the extremities. The CIDP had gone into remission 1 year previously and the sensory deficits had improved, but the tremors had gradually worsened: severe 8-12-Hz postural, kinetic, and resting tremors were present in both upper extremities. Right VIM-DBS was performed and the tremors on the left side showed marked improvement. Over the next 8 years, the tremors were well controlled and there were no relapses of CIDP. DBS may achieve long-term improvement of neuropathic tremor caused by CIDP if the CIDP is in remission.

Is Common Trunk Anomaly Frequent in Hemifacial Spasm? Comparison with Normal Subjects Using Magnetic Resonance Imaging.

OBJECTIVE: Hemifacial spasm (HFS) results from vascular compression at the root exit of the facial nerve. Although the underlying etiology has yet to be identified, it has been suggested that congenital vascular anomalies are involved. We have hypothesized common trunk anomaly of the anterior inferior cerebellar artery (AICA) and posterior inferior cerebellar artery (PICA) which may play a role in HFS. However, no previous studies have directly compared the incidence of this anomaly between HFS patients and normal subjects. The present study was designed to address this gap in the literature. METHODS: This case-control study compared magnetic resonance angiography data from 65 HFS patients and 65 normal subjects. Dominant AICA/PICA is defined as the absence of PICA/AICA, with the remaining AICA/PICA supplying both vascular territories. The term "common trunk" encompasses both dominant AICA and dominant PICA. The frequency of common trunk and dominant AICA/PICA was compared between the 2 groups. RESULTS: There were no significant differences in the incidence of a common trunk (68.5% and 64.6%), dominant AICA (30.8% and 32.3%) and dominant PICA (37.7% and 32.3%) between the 2 groups. Additionally, no differences were found in the frequency of atherosclerosis risk factors. CONCLUSIONS: There was no apparent association between common trunk anomaly and HFS. It is suspected that some vascular anomalies other than a common trunk are involved in HFS.

Adult-onset Sacral Meningocele Causing a Specific Headache Triggered by Compression or Adoption of a Sitting or Supine Posture.

We report a rare case of adult-onset sacral meningocele where compression triggered a specific headache. A 46-year-old woman presented with a headache, which worsened when she was in a sitting or supine position. A subcutaneous mass was observed on her left buttock, the compression of which also induced headache. No neurological deficits were evident. Lumbar and sacral magnetic resonance imaging demonstrated a meningocele in the left dorsal buttock, connecting to the sacral cerebrospinal fluid (CSF) space, and spinal computed tomography revealed sacral dysplasia. Initial meningocele resection improved the patient's headache, but the cyst recurred 2 years later. Following repeated surgery to reinforce the meningocele orifice, the headache was relieved and has been absent for more than 6 years. The headache was due to intracranial pressure fluctuations due to CSF influx into and drainage from the meningocele. Meningocele development in adulthood can be owing to a spinal bone defect and pressure load on the spinal dura. Surgical resection can improve symptoms resulting from meningocele, and reinforcement of the orifice using an artificial surgical membrane effectively prevents recurrence.

A Case of Unilateral Facial Spasm With Vulnerable Hearing Function Due to a History of Cisplatin Treatment, Resulting in Intraoperative Hearing Loss.

A 51-year-old man with a history of cisplatin treatment for a right testicular tumor underwent microvascular decompression for hemifacial spasm. At an early stage in the surgical procedure, the intraoperative auditory brainstem response (ABR) was diminished despite a relatively minimally invasive approach, resulting in irreversible hearing loss. Cisplatin is known to cause dose-dependent hearing impairment primarily affecting the cochlea, but it can also induce neurotoxicity. In the present case, prior cisplatin administration may have caused fragility of the cochlear nerve as well. Patients with a history of ototoxic and neurotoxic drugs such as cisplatin require more careful manipulation and thorough intraoperative auditory monitoring during neurosurgical procedures that may affect hearing, such as those for hemifacial spasms.

[Stereotactic Radiosurgery for Trigeminal Neuralgia].

Stereotactic radiosurgery(SRS)performed with Gamma Knife or CyberKnife has been reported to be effective in treating trigeminal neuralgia(TN). Microvascular decompression is the first choice of treatment for patients with trigeminal neuralgia who are difficult to treat with drugs because of its high efficacy, with a pain relief rate of 70%-80% after 5 years. The pain relief rate of TN treated with SRS is approximately 50%-60% after 5 years, which is less than that of MVD. SRS is also inferior to surgery, causing more frequent sensory disturbances in the trigeminal nerve area(6%-20%). However, the serious complications, severe morbidity and mortality, associated with SRS are quite rare. SRS is an extremely minimally invasive treatment that does not require general anesthesia and can be used to treat TN with short-term hospitalization or outpatient visits.

[Image Diagnosis for Hemifacial Spasm].

Cisternography using heavy T2-weighted images from 3-Tesla magnetic resonance imaging(MRI)and three-dimensional time-of-flight MR angiography(3D TOF MRA)is useful for identifying conflicting vessels in primary hemifacial spasm(HFS). Cisternography provides high-signal images of the cerebrospinal fluid and low-signal images of the cranial nerves and cerebral blood vessels, whereas 3D TOF MRA provides high-signal images with only vascular information. The combination of these two methods increases the identification rate of conflicting vessels. The neurovascular conflict(NVC)site in HFS is where the facial nerve exits the brainstem. However, on MRI, the true NVC site is often more proximal than the facial nerve attachment to the brainstem. On preoperative MRI, it is important to not miss the blood vessels surrounding the proximal portion of the facial nerve. If multiple compression vessels or deep vessels are located in the supraolivary fossette, they may be missed. Coronal section imaging and multiplanar reconstruction(MPR)minimize the chances of missing a compression vessel. Preoperative MRI and CT can also provide various other information, such as volume of the cerebellum, presence of emissary veins, shape of the petrosal bone, and size of the flocculus.

Neuroprotective Effects of Artificial Cerebrospinal Fluid: Analysis of Brainstem Auditory-Evoked Potential Monitoring During Microvascular Decompression in 117 Consecutive Patients.

BACKGROUND AND OBJECTIVES: To study the efficacy of irrigation with artificial cerebrospinal fluid (aCSF) for protection of cranial nerves during surgery; the time required for recovery of brainstem auditory-evoked potentials (BAEPs) that would reflect cochlear function was analyzed in comparison with that for saline irrigation. METHODS: This retrospective study included 117 consecutive patients (95 women, mean age 51.5 ± 11.4 year) who underwent microvascular decompression for hemifacial spasm. During surgery, BAEPs were monitored to avoid damage to the auditory pathways. When a delayed latency of >1 ms or a decrease in amplitude of >50% was detected in BAEP wave V, surgical maneuvers were halted, and the operative field was irrigated with saline or aCSF. Saline was used for irrigation in 58 patients and aCSF in the other 59. The time required for BAEP recovery at the first halt in each patient was analyzed, and the results were compared between the groups. RESULTS: Surgical procedures were interrupted because of BAEP latency delays or decreases in amplitude in 51 of the patients in the saline group and 54 in the aCSF group. In both groups, the latencies and amplitudes recovered significantly with time and both recovered earlier after aCSF irrigation than after saline irrigation. Hearing outcome was not significantly different between 2 groups. CONCLUSION: aCSF is effective for protection of cochlear nerve and promotes recovery from transient dysfunction during surgery. The protective effect may be attributed to multiple factors including conditioned pH, electrolyte composition, glucose, and microelements, such as magnesium and phosphate.

Preoperative findings in relation to the usefulness of endoscopic assistance for microvascular decompression.

PURPOSE: Endoscopy is known to be a useful adjunct for microvascular decompression (MVD) surgery, assisting observation in blind spots such as Meckel's cave in cases of trigeminal neuralgia (TN) and the root exit zone (REZ) in hemifacial spasm (HFS). However, few reports have discussed the usefulness of endoscopy in relation to individual patient characteristics or preoperative magnetic resonance imaging (MRI). METHODS: We retrospectively reviewed the medical records of 109 patients (98 with HFS and 11 with TN, 85 women, median age 55 years) who had undergone endoscopically assisted MVD at our institution between 2017 and 2021. The usefulness of endoscopy in individual cases was scored by three neurosurgeons using a grading scale: 2, essential and indispensable; 1, useful and helpful; 0, not necessary. The mean value of the assigned scores was taken as an indicator of "usefulness," and endoscopy was considered to have been "useful" in cases with a score of > 1.0. RESULTS: Endoscopic assistance was judged to have been useful in 69% of the patients. The proportion of patients evaluated as useful was significantly lower for TN (18.2%) than for HFS (74.5%). Patients with superior cerebellar artery compression had significantly lower scores than patients with other vessels. Endoscopy was considered useful in a significantly higher proportion of patients with anatomically complicated offending vessels (bifurcation or strong meandering) in the REZ detected by preoperative MRI (P < 0.005). CONCLUSION: Endoscopy for MVD is useful for patients with HFS, especially when preoperative MRI shows bifurcation or strongly meandering vessels in the REZ.

Far-field potential of the compound muscle action potential as a reliable marker in amyotrophic lateral sclerosis.

INTRODUCTION/AIMS: Reliable neurophysiological markers in amyotrophic lateral sclerosis (ALS) are of great interest. The compound muscle action potential (CMAP) amplitude has been a conventional marker, although it is greatly influenced by the electrode position. We propose the far-field potential of the CMAP (FFP-CMAP) as a new neurophysiological marker in ALS. METHODS: Patients with ALS and age-matched healthy controls were enrolled. We used a proximal reference (pref) in addition to the conventional distal reference (dref). Routine CMAP was recorded from the belly-dref lead and FFP-CMAP from the dref-pref lead for the ulnar and tibial nerves. Multiple point stimulation motor unit number estimation (MUNE) was also examined in the ulnar nerve. Inter-rater reproducibility was evaluated by two examiners, and some patients were followed up every 3 mo for 1 y. RESULTS: We tested 17 patients with ALS and 10 controls. The amplitudes of routine CMAP and FFP-CMAP in the ulnar and tibial nerves, and hypothenar MUNE value in the ulnar nerve were significantly decreased in ALS compared to controls. Ulnar FFP-CMAP achieved the highest inter-rater intraclass correlation coefficient (ICC) value (0.942) when compared with routine CMAP (0.880) and MUNE (0.839). The tibial FFP-CMAP had a higher ICC value (0.986) than the routine CMAP (0.697). In this way, the FFP-CMAP showed high inter-rater reproducibility because its shape was not much influenced by the electrode position. During 1-y follow-up, decline of CMAP, FFP, and MUNE showed significant correlations with the Amyotrophic Lateral Sclerosis Functional Rating Scale - Revised (ALSFRS-R). DISCUSSION: The FFP-CMAP shows promise as a reliable marker for ALS.

Regression of Acoustic Tumor After Chemotherapy for Ovarian Cancer in a Patient With a Breast Cancer Susceptibility Gene 1 (BRCA1) Germline Mutation.

We report the case of an adult woman who developed ovarian cancer during a follow-up for vestibular schwannoma. Volume reduction of the schwannoma was observed after chemotherapy for ovarian cancer. After ovarian cancer had been diagnosed, the patient was found to have a germline mutation of breast cancer susceptibility gene 1 (BRCA1). This is the first reported case of vestibular schwannoma in a patient with a germline mutation of BRCA1 and the first documented example of chemotherapy including olaparib to have shown efficacy for schwannoma.

Bilateral Low-Frequency Hearing Impairment After Microvascular Decompression Surgery.

BACKGROUND: Hearing impairment is an important complication of microvascular decompression (MVD). In patients after MVD, we have occasionally noted slight to moderate hearing deterioration at low frequencies that is difficult to detect using pure tone average. OBJECTIVE: To assess the incidence and features of low-frequency hearing impairment (LF-HI) after MVD and evaluate its associated factors. METHODS: This single-center, retrospective observational study assessed the audiometric outcome of 270 patients who underwent MVD between January 2015 and December 2020. Preoperative and postoperative hearing levels were compared for each frequency. LF-HI was defined as a hearing deterioration of ≥15 dB at 125, 250, or 500 Hz. The incidence, symptoms, and associated factors of LF-HI were analyzed. RESULTS: Statistical analysis of the patients overall demonstrated slight but significant decreases in the hearing level after MVD at lower frequencies on both the operative and contralateral sides. Eighty-one patients (30.0%) had LF-HI: 49 on the operative side, 24 on the contralateral side, and 8 on both sides, while pure tone average was worsened in 5 patients (1.8%). Subjective symptoms, including hearing deterioration, ear fullness, tinnitus, and dizziness, developed in 10.4% of the patients with LF-HI but improved subsequently within several weeks. "Older age" and "operative side" were associated with LF-HI. CONCLUSION: Decreases in lower-frequency hearing levels in both the ipsilateral and contralateral (nonoperative) ears were observed after trigeminal neuralgia and hemifacial spasm surgery. LF-HI does not cause permanent symptoms but may be a noteworthy phenomenon, possibly involved in the contralateral hearing loss encountered occasionally after other types of posterior cranial fossa surgery.

[Tremor].

Tremor is defined as an involuntary, rhythmic oscillatory movement of a body part. Based on clinical symptoms, tremors are classified into rest, postural, simple kinetic, intention, and task-specific tremors. Pathological conditions associated with tremors include Parkinson's disease, essential tremor, cerebellar tremor, task-specific focal dystonia, peripheral neuropathy induced tremors, tremor secondary to poisoning/drugs, and physiological tremor. In this article, we discuss classifications and tremor etiologies, as well as diagnosis and treatments including surgical management.

Chronic Osteomyelitis of the Cranial Vault in an Adolescent Female: A Case Report.

We report an 18-year-old female patient who developed left temporal headache and fever one month after administration of isotretinoin for acne. Imaging studies demonstrated osteolytic change in the left frontal bone, and the lesion showed gadolinium contrast enhancement. Biopsy confirmed the diagnosis of osteomyelitis, and the symptoms improved after 8 months of medication with antibiotics and nonsteroidal anti-inflammatory drugs (NSAIDs). However, the pain recurred when isotretinoin was resumed. Isotretinoin sometimes causes excessive inflammation, which may have been the reason for the osteomyelitis in this case. Although osteomyelitis is usually caused by bacterial infection, a non-bacterial mechanism should also be suspected if the condition is resistant to antibiotics.

Aspiration Surgery with Appropriate Antibiotic Treatment Yields Favorable Outcomes for Bacterial Brain Abscess.

BACKGROUND: Even in the era of advanced medical treatment, brain abscess still has a high mortality rate. At our institution, brain abscess has been treated mainly using stereotactic or echo-guided aspiration followed by relatively long-term antibiotic treatment, achieving favorable outcomes. To evaluate the efficacy of our strategy involving less-invasive aspiration surgery and long-term selective antibiotic administration for brain abscess, a single-institution series of cases was investigated. METHODS: We retrospectively reviewed and analyzed the medical records of 25 cases of brain abscess treated at Saitama Medical University Hospital between 2008 and 2021. The patients comprised 16 men and 9 women aged between 39 and 85 years (median 62 years). Neurosurgical intervention was performed for 23 (92.0%) of the patients and the remaining 2 received antibiotics alone. RESULTS: Among the neurosurgery patients, 22 (95.7%) underwent echo-guided or stereotactic aspiration, and only 1 underwent craniotomy. Anaerobic bacteria were detected in 11 patients. In the surgical and conservative groups, the median duration of antibiotic treatment was 16 weeks and 23 weeks, respectively. Since 2014 when metronidazole first became available, it has replaced meropenem to cover anaerobic bacteria. The overall mortality rate was 4.0% and a favorable outcome (Glasgow Outcome Scale 4 or 5) was achieved in 76% of the patients. There was no surgical mortality or morbidity. CONCLUSIONS: Most patients underwent aspiration surgery and achieved favorable outcomes. Along with antibiotic treatment for a sufficiently long period to cover anaerobes, this approach can be expected to yield good results.

[Technique of Microvascular Decompression for Hemifacial Spasm Based on Surgical Anatomy].

This article describes the anatomical approach and operative points of microvascular decompression for hemifacial spasm based on the author's personal experience with 1,000 cases. As vascular compression of the facial nerve is often quite caudal, it is necessary to ensure that the compressing arteries in this area are moved. Neither the vessels nor the prosthesis used to move them should not touch the root exit zone of the nerve(vascular transposition nerve isolation technique). It should also be emphasized that every effort should be made to avoid complications such as hearing impairment and postoperative subcutaneous spinal fluid accumulation.

Estimation of the true infection rate and infection fatality rate of coronavirus disease 2019 in each country.

The True Infection Rate (TIR) in the whole population of each country and the Infection Fatality Rate (IFR) for coronavirus disease 2019 (COVID-19) are unknown although they are important parameters. We devised a simple method to infer TIR and IFR based on the open data. The prevalence rate of the Polymerase Chain Reaction (PCR) tests among the population (Examination Rate; ER) and the positive rate of PCR tests (Infection Rate; IR) for 66 countries were picked up at a website 5 times from April 10th to June 13th, 2020, and the trajectory of each country was drawn over the IR vs. ER plot. IR and ER showed a strong negative correlation for some countries, and TIR was estimated by extrapolating the regression line when the correlation coefficient was between -0.99 and -1. True/Identified Case Ratio (TICR) and IFR were also calculated using the estimated TIR. The estimated TIR well coincided with local antibody surveys. Estimated IFR took on a wide range of values up to 10%: generally high in the Western countries. The estimated IFR of Singapore was very low (0.018%), which may be related to the reported gene mutation causing the attenuation of the viral virulence.

Microvascular Decompression for Trigeminal Neuralgia: A Prospective, Multicenter Study.

BACKGROUND: Microvascular decompression (MVD) is the most effective procedure for the long-term management of trigeminal neuralgia (TGN). However, retrospective and single-center studies are inherently biased, and there are currently no prospective, multicenter studies. OBJECTIVE: To evaluate the short- and long-term outcomes and complications in patients with TGN who underwent MVD at specialized Japanese institutions. METHODS: We enrolled patients with TGN who underwent MVD between April 2012 and March 2015. We recorded their facial pain grade and complications at 7 d (short term), 1 yr (mid-term), and 3 yr (long term) postoperatively. RESULTS: There were 166 patients, comprising 60 men and 106 women (mean age 62.7 yr). Furthermore, 105 patients were aged over 60 yr. We conducted neuromonitoring in 84.3% of the cases. The complete pain relief, mortality, and complication rates at the short-term follow-up were 78.9%, 0%, and 16.3%, respectively. Overall, 155 patients (93.4%) completed the long-term follow-up, with the complete pain relief and complication rates of 80.0% and 5.2%, respectively. CONCLUSION: In the hands of experienced neurosurgeons, MVD for TGN can achieve high long-term curative effects. In addition, complications are uncommon and usually transient. Our results indicate that MVD is an effective and safe treatment for patients with TGN, including elderly patients.

Prospective, Multicenter Clinical Study of Microvascular Decompression for Hemifacial Spasm.

BACKGROUND: Microvascular decompression (MVD) is the most effective procedure for hemifacial spasm (HFS). MVD results from nonspecialized or low-volume institutes are not always reliable. Most studies on MVD for HFS are retrospective and single centered; to the best of our knowledge, no prospective, multicenter studies exist. OBJECTIVE: To evaluate short- and long-term outcomes and complications in patients who underwent MVD for HFS in specialized Japanese institutions, in this multicenter, prospective, cohort study. METHODS: Included patients had undergone MVD for HFS in study centers between April 2012 and March 2015. Patients' postoperative grade of involuntary movements and complications were recorded postoperatively at 7 d (short-term) and at 1 (mid-term) and 3 (long-term) yr. RESULTS: A total of 486 patients (150 men, 336 women; mean age 53.9 yr with 181 patients over 60 yr) were enrolled during the study period. Neuromonitoring was used in 96.3% of the cases. The complete cure rate of symptom relief, mortality rate, and complication rate at short-term follow-up were 70.6%, 0%, and 15%, respectively. The long-term follow-up was completed by 463 patients (95.3%); the complete cure rate of symptom relief and complication rate were 87.1% and 3.0%, respectively. CONCLUSION: Our study revealed that under expert guidance and intraoperative neuromonitoring, the long-term curative effect rate of MVD for HFS is high, while complications are uncommon and usually transient. Our results indicate that MVD is an effective and safe treatment for patients with HFS, including elderly patients.

A multi-center, prospective study on the progression rate of asymptomatic ventriculomegaly with features of idiopathic normal pressure hydrocephalus on magnetic resonance imaging to idiopathic normal pressure hydrocephalus.

INTRODUCTION: Our previous community-based study demonstrated that some individuals with AVIM [asymptomatic ventriculomegaly with features of idiopathic normal pressure hydrocephalus (iNPH) on magnetic resonance imaging (MRI)] progressed to iNPH in several years. In this hospital-based study, we investigated the progression rate from AVIM to iNPH and its possible predictors. METHODS: We conducted a prospective study of participants with AVIM from several medical institutions/hospitals in Japan. AVIM is defined as "asymptomatic ventriculomegaly with features of iNPH on MRI"; in the present study, asymptomatic was defined as "0 (no symptoms) or 1 (presence of only subjective, but not objective, symptoms) on the iNPH Grading Scale (iNPH-GS)." We also measured possible predicting factors for AVIM-to-iNPH progression, including age, sex, body weight, blood pressure, diabetes mellitus, dyslipidemia, history of mental disease/head injury/sinusitis/smoking/alcohol-intake, Evans index, and the presence of DESH (disproportionately enlarged subarachnoid-space hydrocephalus) findings on brain MRI, and analyzed these potential predictive values. RESULTS: In 2012, 93 participants with AVIM were registered and enrolled in the study. Of these, 52 participants were able to be tracked for three years (until 2015). Of the 52 participants, 27 (52%) developed iNPH during the follow-up period (11 definite, 6 probable, and 10 possible iNPH), whereas 25 participants remained asymptomatic in 2015. Among the possible predictive factors examined, the baseline scores of iNPH-GS predicted the AVIM-to-iNPH progression. CONCLUSIONS: The multicenter prospective study demonstrated that the progression rate from AVIM to iNPH was ~17% per year, and the baseline scores of iNPH-GS predicted the AVIM-to-iNPH progression.