The Head Retraction Reflex in Niemann‐Pick Type C: A Novel Diagnostic Clue

Abstract

BackgroundThe head retraction reflex (HRR) is characterized by the extension of the neck after percussion stimulation of the central facial region. It is either absent or habituates in normal individuals and can become exaggerated and persistent in certain pathological conditions, having been most commonly reported in hyperekplexia and stiff‐person syndrome disorders. It has not, however, been reported in Niemann‐Pick type C (NPC), a lipid storage disorder with a variety of neurologic and systemic manifestations. The diagnosis of NPC is often delayed because of the rarity of the condition and the subtlety of clinical signs.CasesWe present 3 consecutive cases of genetically confirmed NPC with a pathological HRR, which was not present in controls. Neurophysiological analysis showed findings suggestive of myoclonus of brainstem origin.ConclusionWe propose that the presence of a pathological HRR, an easily performed clinical test, may provide a clue to the diagnosis of NPC.

Myoclonus and other jerky movement disorders

“…Its pathophysiological variant, an exaggerated trigeminocervical reflex with lack of habituation, is thought to represent the head retraction reflex and can be provoked by gentle taps to the glabella, nose ridge, upper lip, and chin. Apart from being present in startle syndromes (see Section 3.3 ), it has been seen in patients with Niemann-Pick type C and Parkinson’s disease, although the latter remains unconfirmed ( Martin et al, 2020 , Sandyk et al, 1982 ). The clinical resemblance lies in the characteristic rostro-caudal propagation with the relative slowly conducting efferent pathways.…”