Intact thumb reflex in areflexic Guillain Barré syndrome: A novel phenomenon

INTRODUCTION: Areflexia is one of the cardinal clinical features for the diagnosis of Guillain Barré syndrome. However, some patients may have sluggish proximal muscle stretch reflexes. Presence of thumb reflex, a distal stretch muscle reflex has not been documented in Guillain Barré syndrome. MATERIALS AND METHODS: We prospectively evaluated thumb reflex in Guillain Barré syndrome patients and age matched controls from April to September 2013. RESULTS: There were 31 patients with Guillain Barré syndrome in whom thumb reflex could be elicited in all (24 brisk, 7 sluggish), whereas all the other muscle stretch reflexes were absent in 29 patients at presentation and the remaining two had sluggish biceps and quadriceps reflexes (P = 0.001). Serial examination revealed gradual diminution of the thumb reflex (P < 0.001). Rapid progression of weakness was associated with early loss of the thumb reflex. CONCLUSION: Thumb reflex, a distal stretch reflex is preserved in the early phase of Guillain Barré syndrome.