Objective: To illustrate the myokymia and tremor-like phenomenon in a patient with chronic inflammatory demyelinating polyradiculoneuropathy.

Background: The clinical manifestations of CIDP are various and around 50% patients may present with atypical features. Some of the patients may manifest with myokymia, tremor or tremor-like phenomenon and may mislead the clinician astray. In this regard, early detection of the atypical features of CIDP is mandatory for early immune intervention.

Method: Here we present a 25-year-old man diagnosed as having CIDP with the first presentation of bilateral hands trembling mimicking essential tremor and myokymia of calf regions was detected incidentally during neurological examination. The deep tendon reflexes were absent in bilateral ankles, brachioradialis, and triceps. Decreased pin-prick sensation in a glove-stocking distribution, diminished joint-position sense, and a positive Romberg test were documented. Nerve conduction velocity (NCV), needle/surface EMG and CSF study were performed for the diagnosis. Blood tests, including anti-voltage-gated potassium channel antibodies (Anti-VGKC), were examined.

Results: Motor NCV revealed decreased conduction velocity with preserved amplitude in the bilateral median and ulnar nerves. Sensory NCV study, H-reflex, and F-waves were mostly unrecordable. Needle EMG disclosed myokymic discharge. Anti-VGKC were negative. Surface EMG recording of bilateral abductor pollicis brevis revealed 6-11 Hz irregular muscle activity. The diagnosis of CIDP was made based on clinical history, NCV/EMG findings and CSF cytological-albuminal dissociation (no pleocytosis, protein 341 mg/dl). The clinical tremor-like features were relevant to myokymic activities of the muscles. His conditions were improved after plasmaphoresis and returned to workplace 2 months later after treatment.

Conclusion: Myokymia and tremor-like movement disorder may be the presenting features of CIDP and the atypical features may make the appropriate diagnosis difficult. Earlier recognition of the unusual presentation is crucial for in time immunological intervention and good outcome.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/myokymia-and-tremor-like-involuntary-movement-in-a-patient-with-chronic-inflammatory-demyelinating-polyradiculoneuropathy/