Kind and distribution of cutaneous sensation loss in hereditary transthyretin amyloidosis with polyneuropathy

Objective: Report on the kind and distribution of somatotopic sensation loss and its utility in assessing severity of sensation loss in study of a large international cohort of patients with hereditary transthyretin amyloidosis with polyneuropathy (hATTR-PN). Methods: Smart Somatotopic Quantitative Sensation Testing (S ST QSTing) using Computer Assisted Sensation Evaluator IVc (CASE IVc) was used to assess the somatotopic distribution of touch pressure (TP) and heat pain (HP) sensation loss twice of untreated hATTR-PN patients in the Ionis NEURO-TTR trial (www.clinicaltrials.gov, NCT01737398). Results: Of the studied cohort of 169 patients, 163 (97%) had sensation loss, both TP and HP in 121/169 (75%), TP only in 39/169 (23%), and HP only in 3/169 (2%). Sensation loss typically affected both lower (152/169-90%) and upper limb (135/169-82%), and overall TP sensation loss was greater than HP loss, except for early-onset Val30Met patients in which HP exceeded TP loss. Conclusion: Using S ST QSTing, a highly quantitated, standardized, referenced, and automated QSTing approach of the body's surface distribution of sensation loss we have shown that: 1) reliable and useful measurement of the body surface distribution of sensation loss is possible; 2) this measure is abnormal in most patients with hATTR-PN and is an indication of polyneuropathy severity; and 3) cutaneous sensation loss involves both large and small sensory fibers in this disease but slightly more small fibers in early onset Val30Met patients.