Jonathan Morena

Introduction: Intraneural ganglion cysts can arise from the peroneal nerve at the lateral knee secondary to synovial fluid tracking along the articular branch and transforming within the nerve into a mucinous cyst, resulting in nerve compression. Case Report: A 17-year-old right-handed male presented with a four-month history of right foot drop. He is physically active and attributed the foot drop to a sprained ankle. EMG/NCS showed a right common peroneal neuropathy distal to the innervation of the biceps femoris short head with active denervation. MRI showed an intraneural ganglion cyst in the common peroneal nerve starting at the level of biceps femoris. On exam, he had right foot drop and sensory deficits referable to the peroneal distribution, along with a right steppage gait. He had successful decompression of the ganglion cyst, excision of the articular branch and resection of the proximal tibiofibular joint, with clinical improvement. Conclusion: Early recognition and surgical treatment leads to better outcomes for patients when an intraneural ganglion cyst results in neurologic deficits. Physical activities and trauma, which increase stress on the knee joints, may predispose ganglion cyst formation within peroneal nerves. Fibers of the deep peroneal nerve may be preferentially affected when compared to the superficial peroneal nerve. Disconnection of the articular branch and proximal tibiofibular joint resection may decrease risk of recurrence.

Background: Parsonage‐Turner syndrome (PTS) is characterized by severe, acute upper extremity pain and subsequent paresis and most commonly involves the long thoracic nerve (LTN). While MR neurography (MRN) can detect LTN hourglass‐like constrictions (HGCs), quantitative muscle MRI (qMRI) can quantify serratus anterior muscle (SAM) neurogenic changes.Purpose/Hypothesis: 1) To characterize qMRI findings in LTN‐involved PTS. 2) To investigate associations between qMRI and clinical assessments of HGCs/electromyography (EMG).Study Type: Prospective.Population: 30 PTS subjects (25 M/5 F, mean/range age = 39/15–67 years) with LTN involvement who underwent bilateral chest wall qMRI and unilateral brachial plexus MRN.Field Strength/Sequences: 3.0 Tesla/multiecho spin‐echo T2‐mapping, diffusion‐weighted echo‐planar‐imaging, multiecho gradient echo.Assessment: qMRI was performed to obtain T2, muscle diameter fat fraction (FF), and cross‐sectional area of the SAM. Clinical reports of MRN and EMG were obtained; from MRN, the number of HGCs; from EMG, SAM measurements of motor unit recruitment levels, fibrillations, and positive sharp waves. qMRI/MRN were performed within 90 days of EMG. EMG was performed on average 185 days from symptom onset (all ≥2 weeks from symptom onset) and 5 days preceding MRI.Statistical Tests: Paired t‐tests were used to compare qMRI measures in the affected SAM versus the contralateral, unaffected side (P < 0.05 deemed statistically significant). Kendall's tau was used to determine associations between qMRI against HGCs and EMG.Results: Relative to the unaffected SAM, the affected SAM had increased T2 (50.42 ± 6.62 vs. 39.09 ± 4.23 msec) and FF (8.45 ± 9.69 vs. 4.03% ± 1.97%), and decreased muscle diameter (74.26 ± 21.54 vs. 88.73 ± 17.61 μm) and cross‐sectional area (9.21 ± 3.75 vs. 16.77 ± 6.40 mm²). There were weak to negligible associations (tau = −0.229 to P = 0.054–1.00) between individual qMRI biomarkers and clinical assessments of HGCs and EMG.Data Conclusion: qMRI changes in the SAM were observed in subjects with PTS involving the LTN.Level of Evidence: 2Technical Efficacy: Stage 1

Introduction: Facial Onset Sensory and Motor Neuronopathy (FOSMN) typically presents with paresthesias in the trigeminal nerve distribution and weakness that progresses rostro-caudally. Objective: To present two new cases of FOSMN, summarize the current literature, and address areas for future study. Methods: Observational data was collected from two patients with FOSMN from our institution. A literature review of FOSMN was completed using PubMed. Results: We identified 100 cases of FOSMN, including our two new cases. 93% presented with facial paresthesias. 97% had bulbar symptoms. Five had family history of ALS. Abnormal Blink reflex was most common on EMG/NCS. CSF was typically normal, but a rare severe case showed elevated protein. Mutations included: TARDBP, OPMD, D90A-SOD1, CHCHD10, VCP, and SQSTM1. Neuropathological studies showed neurodegenerative changes without inflammation. Some cases have reported transient stabilization or improvement to immunomodulatory therapy. Case Reports: A 72-year-old man presented with right-sided trigeminal paresthesias that progressed in a rostro-caudal fashion, dysphagia, and hand weakness. He died 4-5 years after symptom onset. A 69-year-old man presented with left-sided jaw paresthesias, dysphagia and dysarthria. He was trialed on IVIG for 1.5 years without improvement and died 2.6 years after symptom onset. Conclusion: FOSMN is a rare disorder with a unique clinical and electrophysiological phenotype. The pathophysiology has been associated with neurodegeneration and multiple gene mutations have correlated to FOSMN. Some reports suggest transient response to immunomodulatory therapy, though prospective studies are lacking. CSF protein elevation may be seen in severe disease. Future studies will help further elucidate the approach to diagnosis, treatment, and prognostic counseling (biomarkers).

Post-vaccination CNS demyelinating syndromes have been reported with a variety of vaccines including the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines. We report a case of myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) probably associated with the mRNA-1273 (by Moderna) SARS-CoV-2 mRNA vaccine, and a case of acute transverse myelitis (ATM) probably associated with the BNT162b2 (by Pfizer-BioNTech) SARS-CoV-2 mRNA vaccine. A 38-year-old man developed left blurry vision, lower extremity weakness/paresthesia, and bowel/bladder dysfunction three days after receiving the Moderna vaccine. He was diagnosed with left optic neuritis and longitudinally extensive transverse myelitis; he tested positive for the myelin oligodendrocyte glycoprotein antibody. A 39-year-old woman presented with progressive lower extremity weakness/numbness 7 days after receiving the Pfizer vaccine. She was diagnosed with ATM. Both patients improved with intravenous corticosteroids. The association between CNS demyelinating syndromes and vaccination has been reported for many years. We describe two cases of acute CNS demyelinating events probably associated with both mRNA variations of the SARS-CoV-2 vaccines. While the risk of CNS demyelinating events is non-negligible, the incidence is very low and the overall benefits of vaccination outweigh the marginal risk. However, providers should be aware of this potential neurological complication of the SARS-CoV-2 mRNA vaccines.

Transient global amnesia (TGA) consists of acute-onset anterograde amnesia and typically resolves within 24 hours. Reported etiologies of TGA include transient ischemia to the hippocampus or thalamus, migraine, venous flow abnormalities, and epilepsy. There are no reports of cerebellar ischemia as an etiology of TGA. A 78-year-old woman with a medical history of diabetes presented to the Ohio State University ER after a period of anterograde amnesia lasting 3 hours. She was alert during the event, but asked the same questions repeatedly. Upon arrival to the ER, she was hypertensive but clinically back to baseline, with no recall of the 3-hour time period. An MRI of her brain revealed an isolated hyperintense signal on diffusion-weighted imaging (DWI) at the junction of the superior cerebellum and vermis, with apparent diffusion coefficient correlation. Vascular imaging of the brain and neck and a routine EEG were unremarkable. We diagnosed her with cerebellar ischemia presenting as TGA. She had no head injury, migraine, or history of epilepsy to suggest alternative etiologies of TGA. An increasing amount of literature has reported that the cerebellum is linked to the limbic system. A case series of SPECT imaging on individuals with TGA revealed transient cerebellar vermis hypoperfusion in addition to hippocampal DWI changes. We present what may be a novel report of isolated cerebellar ischemia presenting as TGA, and we add to the literature for clinicians to consider the possibility that damage to the cerebellum or its circuit to the cerebrum or thalamus can present as TGA.

MFS has been reported to recur in 10-12% of patients. There may be a genetic component related to HLA-DR2. Anti-GAD antibodies can be present in MFS along with anti-GQ1b. Common EMG/NCS associations consist of a predominantly axonal, sensory polyneuropathy and absent H reflexes. A 32-year-old female with a history of hypothyroidism presented to our institution twice with symptoms of diplopia, lower extremity weakness and distal paresthesias occurring a year apart. She had ophthalmoplegia, reduced reflexes, and ataxia on exam. CSF showed a borderline elevated protein of 47 and white blood cells <3. She was positive for anti-GQ1b both times. Her anti-GAD65 antibody was elevated during both admissions. EMG/NCS on her first admission revealed comparatively reduced sensory nerve action potentials (SNAPs) and a normal blink reflex. Her SNAPs improved on the second admission, however, the EMG was performed only 2 days after the onset of her symptoms, limiting some early findings that may have not matured electrophysiologically. She was treated with IVIG on both occasions with rapid recovery within 5 days. This case highlights the fact that MFS can be recurrent. It also provides further evidence that anti-GAD antibodies may be associated with MFS. Reported findings of the blink reflex in MFS are diverse and further data is needed to determine if certain findings are more predominant than others. Treatment typically consists of IVIG, though steroids may also be considered for recurrence. Prognosis is generally favorable, regardless of treatment.

Charcot-Marie-Tooth (CMT) is the most prevalent category of inherited neuropathy. The most common inheritance pattern is autosomal dominant, though there also are X-linked and autosomal recessive subtypes. In addition to a variety of inheritance patterns, there are a myriad of genes associated with CMT, reflecting the heterogeneity of this disorder. Next generation sequencing (NGS) has expanded and simplified the diagnostic yield of genes/molecules underlying and/or associated with CMT, which is of paramount importance in providing a substrate for current and future targeted disease-modifying treatment options. Considerable research attention for disease-modifying therapy has been geared towards the most commonly encountered genetic mutations (PMP22, GJB1, MPZ, and MFN2). In this review, we highlight the clinical background, molecular understanding, and therapeutic investigations of these CMT subtypes, while also discussing therapeutic research pertinent to the remaining less common CMT subtypes.