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 MRI.

PURPOSE: 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), 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 two 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 two 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.

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.

[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.

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.

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.

Natural Dural Defect of the Posterior Fossa Dura as a Risk Factor for Postoperative Cerebrospinal Fluid Leakage.

BACKGROUND: During microvascular decompression surgery (MVD), small (2-3 mm diameter) natural dural defects have been noticed occasionally but never reported. These tiny dural defects cannot be detected by preoperative imaging studies or even in anatomical cadaver dissection, but may lead to complications including cerebrospinal fluid (CSF) leakage. Our objective was to analyze the features of these natural defects in the posterior fossa dura. METHODS: Surgical reports and videos of 593 consecutive patients who underwent MVD surgery for trigeminal neuralgia (TN) or hemifacial spasm (HFS) were analyzed retrospectively. Video recording confirmed that these small holes were not related to the craniotomy procedure itself and were natural defects. RESULTS: Such natural defects of the posterior fossa dura were found in 6 of the 593 patients. All of the defects were about 2 mm in diameter and occurred on the left side in female patients with HFS. All were managed by patching with a fascial or muscle graft. Multivariate analysis showed that the defect was significantly associated with the left side and had a female predilection. Neither disease (HFS or TN) nor age was correlated with the presence of dural defects. CONCLUSIONS: After posterior fossa craniotomies, CSF leakage or pseudomeningocele may occur at the dural suture site because of the hydrostatic pressure. Because such natural dural defects may be a cause of CSF complications after posterior fossa surgery, their possible occurrence should be considered. This is the first report to document the occurrence of such natural defects of the posterior fossa dura.

Preservation of the Lesser Occipital Nerve Prevents Occipital Sensory Disturbance After Microvascular Decompression: Long-Term Results.

BACKGROUND: In microvascular decompression (MVD) surgery for hemifacial spasm (HFS), preservation of the lesser occipital nerve (LON) will prevent occipital sensory disturbance, a frequent complication of MVD, but the long-term outcome is unknown. This study was designed to evaluate the long-term efficacy of LON preservation. METHODS: This retrospective study included 257 patients with HFS who underwent suboccipital craniotomy with MVD. Among them, 175 were followed-up for more than 2 years. Occipital sensation was examined at 1, 12, and 24 months after MVD. The patients were classified into 3 groups based on their operative findings: LON preservation (group A; n = 112), LON not identified (group B; n = 117), and LON excision (group C; n = 28). The degree of sensory disturbance was evaluated using a visual analog scale (VAS) ranging from 1 (no sensation) to 10 (intact). RESULTS: The VAS score at 1 month was significantly better in group B (7.9 ± 0.2) than in groups A and C (7.3 ± 0.2 and 6.8 ± 0.4, respectively). At 24 months, the VAS scores were significantly higher in groups A and B (9.7 ± 0.1 and 9.7 ± 0.1) than in group C (8.8 ± 0.4), and occipital scalp sensation remained intact (VAS scores 9 and 10) in 91.9%, 92.9%, and 62.5% of the patients in groups A, B and C, respectively. CONCLUSIONS: Our long follow-up study has demonstrated that preservation of the LON during MVD prevents sensory disturbance of the occipital scalp. Efforts to preserve the LON appear to be worthwhile when the suboccipital approach is chosen.

Surgical Technique and Outcome of Extensive Frontal Lobectomy for Treatment of Intracable Non-lesional Frontal Lobe Epilepsy.

Although extensive frontal lobectomy (eFL) is a common surgical procedure for intractable frontal lobe epilepsy (FLE), there have been very few reports regarding surgical techniques for eFL. This article provides step-by-step descriptions of our surgical technique for non-lesional FLE. Sixteen patients undergoing eFL were included in this study. The goals were to maximize gray matter removal, including the orbital gyrus and subcallosal area, and to spare the primary motor and premotor cortexes and anterior perforated substance. The eFL consists of three steps: (1) positioning, craniotomy, and exposure; (2) lateral frontal lobe resection; and (3), resection of the rectus gyrus and orbital gyrus. Resection ahead of bregma allows preservation of motor and premotor area function. To remove the orbital gyrus preserving anterior perforated substance, it is essential to visualize the olfactory trigone beneath the pia. It is important to observe the surface of the contralateral medial frontal lobe for complete removal of the subcallosal area of the frontal lobe. Thirteen patients (81.25%) became seizure-free and three patients (18.75%) continued to have seizures. None of the patients showed any complications. The eFL is a good surgical technique for the treatment of intractable non-lesional FLE. For treatment of epilepsy by eFL, it is important to resect the non-eloquent area of the frontal lobe as much as possible with preservation of the eloquent cortex.

A Large Mass Mimicking Calcified Hematoma of the Skull Showing Involvement of Myeloma Cells and a Good Response to Irradiation.

Patients with multiple myeloma often show skull bone involvement, although in most cases this is manifested as skull erosion and large masses develop only rarely. Here we report a patient who presented with a large cranial mass mimicking a subdural hematoma with calcification. The tumor shrunk with 37.5 Gy of focal irradiation in 15 fractions after biopsy. After irradiation the patient was treated with Bortezomib but died because of adverse events. The differential diagnosis of lenticular lesion of the skull and treatment strategy for large skull mass with myeloma cells are discussed.

Trigeminal Neuralgia Due to Petrosal Bone Deformity.

BACKGROUND: There have been a few previous reports of trigeminal neuralgia caused by bony structures. We report a rare case of trigeminal neuralgia caused by petrous bone deformity. CASE DESCRIPTION: A-43-year-old man with facial pain in the left maxillary and mandibular divisions of the trigeminal nerve was referred to our hospital. Computed tomography showed bone hyperplasia protruding into the left cerebellopontine cistern, compressing the left trigeminal nerve. Administration of carbamazepine ameliorated facial pain, but the effect was unsatisfactory, and microvascular decompression was performed through the anterior transpetrosal approach. The protruding petrous bone was drilled out to release compression of the trigeminal nerve, thus straightening the deviated trajectory of the nerve. The superior cerebellar artery adjacent to the thickened petrosal bone seemed to have compressed the trigeminal nerve and was also transposed. The facial pain disappeared completely after microvascular decompression surgery. CONCLUSIONS: The anterior transpetrosal approach is an appropriate and essential strategy for trigeminal neuralgia caused by petrous bone deformity of the petrous apex.

Implicit phonetic symbolism in voicing of consonants and visual lightness using Garner's speeded classification task.

The present study examines implicit phonetic symbolism which posits that arbitrary linguistic sound is related to certain aspects of characteristics of other modalities, such as color, touch, or emotion. In consonant discrimination and lightness discrimination using Garner's speeded classification paradigm, spoken sounds (voiced/voiceless consonants) and lightness of visual stimuli (black/white squares) were systematically varied to assess cross-modal interactions. Congruent audio-visual pairs (voiced consonants and black, and between voiceless consonants and white) facilitated consonant discrimination. In lightness discrimination, no congruent facilitation or congruence effect was observed. These results indicated that cross-modal interactions in implicit phonetic symbolism can be found in correlations between linguistic spoken sounds and visual lightness.