Established and novel measures of upper limb impairment in children with Charcot-Marie-Tooth disease type 1A and Riboflavin Transporter Deficiency type 2.

Hand function is a problem in patients with Charcot-Marie-Tooth disease type 1A (CMT1A) and Riboflavin Transporter Deficiency type 2 (RTD2). However, a detailed understanding of upper limb involvement in these conditions is lacking. The aim of this pilot study was to compare hand and upper limb function between children with CMT1A, RTD2 and healthy controls using established and novel outcome measures. Three age-and sex-matched groups of four children (5-15 years, 1 male/group) with CMT1A, RTD2, and healthy controls were assessed for function, strength, and sensation. Fatigue and muscle activity of the FDI was also assessed using a submaximal contraction at 40% of the participants' maximal voluntary contraction. Functional measures were most affected in children with RTD2 followed by children with CMT1A, compared to healthy controls. Strength was similarly impaired in CMT1A and RTD2 compared to controls (p < 0.05). Sensation was significantly impaired in RTD2 compared to CMT1A and controls (p = 0.008). While time to fatigue did not differ between groups, a decline in muscle activity while force remained constant showed that controls compensated with other muscles during the fatigue task while children with CMT1A and RTD2 did not have this compensatory ability. Children with CMT1A and RTD2 exhibited marked hand/upper limb impairment. These results suggest the upper limb should be a focus of rehabilitative therapy in affected children using sensitive outcome measures of strength and sensation, as well as functional activities of daily living, which are most relevant to the patient.