Objective:

To present a case of Anti-GQ1b antibody syndrome with predominant generalized myoclonus and ataxia. 

Background:

Anti-GQ1b antibody syndrome represents a group of disorders with a common serological profile. Most common presentations include Miller Fischer syndrome and Bickerstaff brainstem encephalitis which can present a variety of neurological symptoms.  We present an intriguing case on a similar spectrum with predominant symptoms of generalized myoclonus and ataxia. 

Design/Methods:

NA

Results:

A 69-year-old left-handed man presented with 4-6 weeks of progressive confusion, generalized myoclonus, and falls. Symptom onset was preceded by an upper respiratory tract infection 1-2 weeks prior, after returning from a festival in the Dominican Republic. Symptoms began with generalized myoclonus which he noticed as difficulty typing on his computer. Symptoms progressed to confusion which manifested as difficulty performing daily activities.  He later developed balance difficulties resulting in multiple falls which prompted him to come to the hospital. Neurological exam was significant for generalized myoclonus, areflexia, and truncal ataxia. Initial work up was unrevealing for infectious or metabolic derangements. MRI brain with and without contrast was negative for any structural abnormalities. Cerebrospinal fluid (CSF) analysis revealed albumino-cytologic dissociation, and serum anti-GQ1b antibody was positive. Paraneoplastic panel in serum and CSF was negative. He was treated with a 5-day course of IVIG followed by 5 days of plasma exchange with improvement in myoclonus and ataxia.  

Conclusions:

This case highlights the importance of anti-GQ1b syndrome as a spectrum of clinical findings rather than typical features, such as presentation with predominant symptom of myoclonus. It is important to recognize these atypical features as a part of spectrum to make a diagnosis and timely management.