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.

[Vertigo/Dizziness as a Common Disease: Thinking in Terms of Risk].

Vertigo and dizziness are among the most common chief complaints in the neurology and emergency departments. Benign, self-limiting peripheral causes such as benign positional paroxysmal vertigo or vestibular neuropathy, Ménière's disease are the majority, but dangerous underlying conditions such as cerebrovascular or cardiovascular diseases are still overlooked. In this paper, the anatomy of the vestibular network from peripheral to central and the classification based on "triggers and timing" rather than the analysis of patient's word (rotational versus dizzy) are presented. Based on these, I classify various causes of vertigo and dizziness into three groups, i.e. highly dangerous, less dangerous but cautionary, and benign self-limiting ones, and explain them focusing on isolated vertigo or isolated vestibular syndrome.

[Neuroleptic Intolerance and Residual Mutism in a Young Woman with Anti-N-Methyl-D-Aspartate Receptor (NMDAR) Encephalitis].

We report a case of anti-NMDAR encephalitis and residual mutism in a 23-year-old woman who presented with neuroleptic intolerance. Admission to our department for investigation of her abnormal behavior revealed cerebrospinal fluid (CSF) positivity for anti-NMDAR antibodies, and the patient underwent immunotherapy. However, generalized tonic seizures developed, requiring mechanical ventilation in the intensive care unit. Antipsychotic drugs were also administered for involuntary movements and insomnia. Thereafter, a malignant syndrome of severe hyperCKemia (Max: 191,120 IU/L) and shock developed, requiring resuscitation and three sessions of hemodialysis. Subsequent rituximab therapy led to improvement, except for mutism, which had newly developed during resuscitation. Seven months after initial admission, the patient was discharged with independent gait. However, her mutism still persists. Temporary mutism has been reported to occur in this type of encephalitis, albeit rarely. The fact that remission was not observed in this case may have been due to cerebellar infarction occurring during resuscitation, but the true cause remains unclear. Malignant syndrome or rhabdomyolysis, as seen in this patient, has also sometimes been reported in this form of encephalitis when antipsychotic agents, especially dopamine receptor blockers, have been administered. Therefore, such agents should be administered with caution in patients with anti-NMDAR encephalitis. (Received August 17, 2023; Accepted October 24, 2023; Published March 1, 2024).