Neurophysiological evaluation of areflexia in Holmes-Adie syndrome

Purpose - To evaluate ankle areflexia in Holmes-Adie syndrome (HAS). Patients and methods - Hoffmann (H) and Tendon (T) soleus reflexes, tonic vibration reflex (TVR), and polysynaptic extension reflex of soleus muscle (PERS) were evaluated in eight patients with idiopathic HAS. Motor (MNCV) and sensory (SNCV) nerve conduction velocities, compound motor-action potential (CMAP), and sensory action potential (SAP) were also determined in upper and lower limbs. Results - Soleus T reflex was obtained in one out of eight patients, and H-reflex was found in none of the patients. TVR was recorded in four out of eight patients, and PERS in all of the patients. MNCV, SNCV, CMAP and SAP showed normal values in all patients. In six out of the eight patients a late response following the tibial nerve stimulation showed constant latency, amplitude and morphology, with no recovery cycle or vibration inhibition. Conclusion - In this study, the neurophysiological spinal reflex circuitry evaluations support the view that HAS ankles areflexia is due to a selective impairment of monosynaptic connections of Ia afferents. A normal nuclear excitability is suggested by polysynaptic activation of the soleus motor nucleus.