Correlation between Delayed Relief after Microvascular Decompression and Morphology of the Lateral Spread Response in Patients with Hemifacial Spasm-Further Examination with Compound Motor Action Potentials.

Although microvascular decompression (MVD) is a reliable treatment for hemifacial spasm (HFS), postoperative delayed relief is one of its main issues. We previously evaluated the morphology of the lateral spread response (LSR) and reported correlation between delayed relief after MVD and polyphasic morphology of the LSR. This study aimed to investigate the morphology of LSR and the course of recovery of the compound motor action potential (CMAP), to better understand the pathophysiology of delayed healing of HFS. Based on the pattern of the initial LSR morphology on temporal and marginal mandibular branches stimulation, patients were divided into two groups: the monophasic and polyphasic groups. The results of MVD surgery and sequential changes in the CMAP were evaluated 1 week, 1 month, 1 year, and final follow-up after the surgery. Significantly higher rates of persistent postoperative HFS were observed in patients with the polyphasic type of initial LSR at 1 week and 1 month after the surgery (P < 0.05, respectively). In the polyphasic group, the amplitude of the CMAP tended to gradually improve with time, while in the monophasic group, the amplitude of the CMAP decreased on the seventh postoperative day, followed by its gradual improvement. There is a significant correlation between delayed relief after MVD and polyphasic morphology of the initial LSR in patients with HFS. In the polyphasic group, CMAP recovered earlier and showed less reduction in amplitude, suggesting segmental demyelination, with less damage to peripheral nerves.

[Surgical Techniques for Microvascular Decompression in Hemifacial Spasm].

This study discusses the key microvascular decompression(MVD)techniques for the treatment of hemifacial spasm(HFS). The author's experience is based on their institution's cases, highlighting three critical techniques. (1)Vertebral artery(VA)repositioning: Repositioning the VA is essential in challenging cases. This article focuses on the relocation of the proximal portion of the VA and the importance of careful dissection. (2)Relocating vessels compressing the peripheral branches of the facial nerve: HFS can result from nerve compression at various locations, including the cisternal portion. This study addressed cisternal compression and considered the nearby nerves. (3)Considering the perforating branches during repositioning, cases may involve complex branching of the perforating arteries. This paper describes an approach that carefully repositions the vessels without damaging the perforating branches. The results from 100 VA-involved cases showed excellent outcomes, with 91.2% of patients experiencing T0(excellent)results. This study emphasized the need to adapt the surgical approach to each unique case to ensure the safety and effectiveness of MVD. This study provides insights into the critical MVD techniques for HFS, emphasizing the importance of continuous experience and knowledge accumulation. These techniques can be learned by other neurosurgeons, thereby expanding the availability of safe and successful MVD procedures for HFS.

Objectively-captured Changes in Trigeminal Fibers before and after Microvascular Decompression Using 3D T2-SPACE MRI Might Relate to Eventual Residual Symptoms.

Although microvascular decompression (MVD) is a reliable treatment for trigeminal neuralgia (TN), neurosurgeons sometimes encounter patients whose symptoms do not improve postoperatively or who experience good treatment efficacy but develop other sensory disturbances. This study aims to objectively identify changes in nerve fibers before and after surgery by MRI and to clarify the relationship between the changes and residual postoperative symptoms. We retrospectively analyzed data from 36 consecutive patients who underwent MVD for classical TN at our hospital between November 2019 and November 2020. Cases that fulfilled the diagnostic criteria for multiple sclerosis were excluded. We confirmed the changes on the brainstem side of the trigeminal nerve preoperatively and at seven days postoperatively using 3D T2-SPACE MRI, in which the patients were divided into three groups: preoperative T2 high intensity positive (A), postoperative T2 high intensity positive (B), and no T2 high-intensity region (C). The primary outcome measures were therapeutic efficacy and frequency of postoperative numbness. The results of MVD surgery were evaluated one year postoperatively. The percentage of cases in which treatment outcomes were rated as excellent or good at one year: group A: 0 (0%), group B: 6 (100%), and group C: 25 (96.2%) (p < 0.05); the frequency of numbness: 2 (50%) in group A, 3 (50%) in group B, and 1 (3.8%) in group C, indicating significant differences between the three groups (p < 0.05). 3D T2-SPACE MRI sequences can be used to identify changes in trigeminal nerve fibers before and after MVD, which might correlate with eventual residual symptoms.

Microvascular Decompression for Concurrent Trigeminal Neuralgia and Hemi-Laryngopharyngeal Spasm: A Case Report.

BACKGROUND AND IMPORTANCE: Hemi-laryngopharyngeal spasm (HeLPS) may result from vascular compression of the vagus nerve and can be treated using microvascular decompression. We describe the clinical characteristics and surgical treatment in a case of concurrent trigeminal neuralgia (TN) and HeLPS. CLINICAL PRESENTATION: A 44-year-old man presented with a 12-month history of right TN and 8-month history of intermittent episodes of repeated throat contractions associated with a very distressing choking sensation. Preoperative 3-dimensional fusion imaging demonstrated compression of the trigeminal nerve by the superior cerebellar artery and petrosal vein and compression of the vagus nerve by the posterior inferior cerebellar artery and one of its branches. Microvascular decompression was performed by a right standard retrosigmoid approach with enlarged craniotomy. Initially, the compression of the trigeminal nerve was identified by visual inspection. All the offending vessels were wrapped in Teflon felt, transposed away from the trigeminal nerve, and adhered to the tentorial membrane and petrous bone using fibrin glue. Furthermore, observation of the caudal rootlets of the vagus nerve revealed that the posterior inferior cerebellar artery and its branch compressed the ventral side of the nerve. These vessels were displaced antero-caudally with Teflon felt and fibrin glue; no other vessels were found around the trigeminal and vagus nerves. Postoperatively, the patient had immediate and complete resolution of symptoms of TN and HeLPS without recurrence at the 18-month follow-up. CONCLUSION: HeLPS may occur with TN, and neurosurgeons should identify the symptoms suspicious of this disease preoperatively.

Significant Correlation between Delayed Relief after Microvascular Decompression and Morphology of the Abnormal Muscle Response in Patients with Hemifacial Spasm.

Although microvascular decompression (MVD) is a reliable treatment for hemifacial spasm (HFS), postoperative delayed relief of persistent HFS is one of the main issues. In patients with hemifacial spasm, stimulation of a branch of the affected facial nerve elicits an abnormal response in the muscles innervated by another branch. Several specific types of waves were found in the abnormal muscle response (AMR). This study aimed to confirm the relationship between the initial morphology of the AMR wave and delayed relief of persistent HFS after MVD. We retrospectively analyzed and compared the data from 47 of 155 consecutive patients who underwent MVD for HFS at our hospital between January 2015 and March 2020. Based on the pattern of the initial AMR morphology on orbicularis oculi and mentalis muscle stimulation, patients were divided into two groups, namely, the monophasic and polyphasic groups. The results of MVD surgery for HFS were evaluated 1 week, 1 month, and 1 year postoperatively, by evaluating whether or not the symptoms of HFS persisted at the time of each follow-up. There were significantly higher rates of persistent postoperative HFS in patients with the polyphasic type of initial AMR at 1 week and 1 month after the surgery (p < 0.05, respectively), as assessed using Yates chi-squared test and Fisher's exact test. A significant correlation was observed between delayed relief after MVD and polyphasic morphology of the AMR in electromyographic analysis in patients with hemifacial spasm.

Intravenous Fosphenytoin Therapy as an Acute Rescue Treatment for Glossopharyngeal Neuralgia Crisis in Patients Awaiting Neurosurgical Procedures: A Case Series.

INTRODUCTION: Few treatments exist for acute attacks of glossopharyngeal neuralgia (GPN). We investigated the efficacy of intravenous fosphenytoin therapy (IFT) during GPN crisis. CASE PRESENTATION: We evaluated records of 4 consecutive patients with GPN awaiting microvascular decompression (MVD) who received IFT (total, 750 mg). Pain severity was evaluated using a Numerical Rating Scale (NRS). The score was 10 (maximum pain) before treatment. Case 1 (a 52-year-old woman, left GPN): for 12 hours after IFT, pain was eliminated (NRS 0/10); however, severe pain recurred 2 days later. She received MVD 9 days after IFT. Case 2 (a 72-year-old woman, right GPN): pain score reduced to 0/10 immediately after IFT and remained so for 2 days. Severe pain recurred, and she underwent MVD 4 days after IFT. Case 3 (a 69-year-old woman, right GPN): pain was reduced (NRS, 5/10) immediately after IFT and nearly eliminated (1/10) 1 hour later. After 6 hours, severe pain recurred; she received a second IFT 3 days later, and pain score dropped to 1/10. She was pain-free for 24 hours but intermediate pain recurred in 2 days. Microvascular decompression was performed 9 days after the second IFT. Case 4 (a 32-year-old woman, right GPN): Pain score reduced to 0/10 immediately after IFT and remained so for 4 days. She underwent MVD 4 days after IFT. No evidence of recurrence was found throughout the 24-, 22-, 20-, and 5-month follow-ups. CONCLUSIONS: These results provide new insights into the innovative therapeutic option of intravenous fosphenytoin and contribute to advancements in treating acute GPN crisis.

Lateral Supracerebellar Infratentorial Approach for Superior Oblique Myokymia: A Case Series.

BACKGROUND: Few reports have shown that superior oblique myokymia (SOM) may result from vascular compression of the trochlear nerve and may be curable using microvascular decompression (MVD). OBJECTIVE: To report the clinical characteristics and surgical treatment of 2 cases of SOM and provide a review of the related literature. METHODS: Two patients with SOM were treated using MVD with the lateral supracerebellar infratentorial approach. The patients underwent diagnostic magnetic resonance imaging and three-dimensional fusion imaging preoperatively. A lateral suboccipital craniotomy was performed in the park-bench position. The trochlear nerve and branches of the superior cerebellar artery were confirmed after opening the cerebellomesencephalic fissure over the tentorial surface of the cerebellum. The vessel, which compressed the root exit zone of the trochlear nerve, was transposed far from the nerve and attached to the surface of the midbrain using Teflon felt and fibrin glue. RESULTS: The first case showed compression on both the ventral and rostral sides of the trochlear nerve root exit zone, and the second showed compression only on the ventral side. Large bridging veins on the tentorial surface of the cerebellum complicated the approach in the second case. Postoperatively, both patients had immediate and complete resolution of symptoms without recurrence at the 24-mo and 17-mo follow-ups, respectively. Five previous reports described the complete resolution of SOM after MVD. CONCLUSION: A presentation of an intermittent fluttering ocular sensation should prompt magnetic resonance imaging for ipsilateral trochlear nerve compression. The lateral supracerebellar infratentorial approach allows safe and efficacious MVD for SOM.

Intravenous fosphenytoin therapy for rescue of acute trigeminal neuralgia crisis in patients awaiting neurosurgical procedures: A cross-sectional study.

Few treatments exist for acute attacks of trigeminal neuralgia. Therefore, this study aimed to investigate the efficacy and safety of an intravenous fosphenytoin therapy protocol in a trigeminal neuralgia crisis. We conducted a single-center, retrospective, observational study of the records of 20 patients with trigeminal neuralgia who received intravenous fosphenytoin therapy (15 mg/mL in normal saline at 50 mg/min for 15 min, total 750 mg) during hospitalization between September 2015 and August 2020. Serum phenytoin concentration was measured 30 min post-infusion. Pain severity was evaluated using a numerical rating scale and was analyzed for statistical significance. The mean age of the patients was 67.5 years (female, 50.0%). The median numerical rating scale score (interquartile range) of pain severity was 2.35 (0-10), 0.65 (0-5), 0.15 (0-1), 2.00 (0-8), and 4.30 (0-10) at 15, 30, and 60 min, and 12 and 24 h, respectively (p < .001); the numerical rating scale score was 10 before treatment. Reduction in pain 24 h following treatment was significant. The mean phenytoin concentration was 12.8 µg/mL 30 min post-treatment. While mild dizziness occurred in four patients, all could walk independently within 60 min. The mean age and weight of patients with mild dizziness were significantly higher and lower, respectively (p < .001), than those of other patients. These results may provide physicians with new insights into the innovative therapeutic option of intravenous fosphenytoin and contribute to advancements in treating acute trigeminal neuralgia crisis.