Muscle-specific kinase (MuSK) antibody is seen in 4%-10% of patients with myasthenia gravis (MG), with 40% of these patients reporting bulbar weakness as the initial symptom. We present the case of a 40-year-old woman with MuSK MG whose only presenting symptom was progressive respiratory insufficiency necessitating BiPAP use 16-24 hours daily. She was unresponsive to treatment for cardiac and pulmonary causes and thus referred to neurology. Initial workup directed toward autoimmune and genetic myopathies was unrevealing. MuSK antibodies were positive (60.7 nmol/L, nl 0.00-0.02). Electrodiagnostic studies were unremarkable other than single fiber electromyography which was consistent with a defect in neuromuscular transmission. Treatment with prednisone, plasma exchange, and rituximab led to improvement to reliance on BiPAP only at night. However, her most treatment refractory and quality of life limiting symptom continues to be respiratory insufficiency. Further investigation to better characterize differential response to treatment in this subset of patients with MuSK MG may be needed.

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Seizures have been increasingly identified as a neurologic manifestation of coronavirus disease 2019 (COVID-19) infection. They may be symptomatic due to systemic infections, as a result of direct central nervous system (CNS) invasion, or occur in response to inflammatory reactions to the virus. It is possible that proinflammatory molecules released in response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection can lead to hyperexcitability and epileptogenesis, similar to infections caused by other neurotrophic viruses. Cerebral spinal fluid (CSF) in patients with COVID-19 and seizures is negative for SARS-CoV-2 (PCR) in the majority of patients, but has been found to be positive for proinflammatory molecules like IL-6, IL-8, and anti-neuronal autoantibodies. Electroencephalogram (EEG) in COVID-19 patients are nonspecific. However, in the encephalopathic and critically ill subpopulation, EEG is essential in detecting nonconvulsive seizures and status epilepticus which is associated with increased overall mortality in COVID-19 patients. Thus, as encephalopathy is often the only CNS symptom evidenced in patients with nonconvulsive seizures, more judicious use of continuous EEG in encephalopathic COVID-19 patients should be considered. This would facilitate earlier detection and treatment of seizures in this population, which would ultimately improve outcomes. Further research into the onset and potential for development of seizures and epilepsy in patients with COVID-19 is needed.

Hippocampal ischemia is a rare complication of cocaine abuse that has been thought to arise from vasospasm, anoxic injury, and/or catecholaminergic excitotoxicity. We present two cases of patients abusing cocaine, who presented with an acute onset anterograde amnesia due to bilateral hippocampal ischemia, and had different outcomes. Case 1 is a 49-year-old male with a history of IV heroin abuse who presented after being found down for an unknown period of time. He awoke with no memory of events leading up to hospitalization and was unable to retain new information. Urine toxicology was positive for cocaine and opiates. Traditional vascular risk factors included obesity, hypertension, and hyperlipidemia. His recovery was complicated by continued drug use and one episode of cardiac arrest. Despite cognitive rehabilitation, only minimal improvements in his anterograde memory were observed during his annual follow-up. Case 2 is a 23-year-old male with a history of attention deficit disorder treated with dexmethylphenidate and a history of consistent marijuana and cocaine abuse, who presented with nausea, vomiting, chest pain, shortness of breath, and acute-onset short-term memory loss. Urine toxicology was negative for cocaine and opiates and positive for marijuana. He had no known vascular risk factors. With cognitive rehabilitation and discontinuation of illicit drug use, he demonstrated a significant improvement in his memory function over the course of six months. Brain MRI in both patients showed symmetric bilateral hippocampal diffusion restriction without post-contrast enhancement with corresponding hyperintensities on fluid-attenuated inversion recovery sequences. In both patients, cerebrospinal fluid (CSF) studies were unremarkable for inflammation or infection, and electroencephalograms were normal in awake and drowsy states. Bilateral hippocampal ischemia should be considered as a potential cause of acute onset anterograde amnesia in patients with a history of cocaine abuse. Other substances such as heroin and dexmethylphenidate may potentially increase susceptibility for hippocampal ischemia in patients using cocaine. Discontinuation of illicit drug abuse can influence the degree of recovery from acute bilateral hippocampal ischemia.

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