LAUSR

To the Editor: A 4-year-old boy presented with delay in motor milestones and progressive difficult in walking. His antenatal and perinatal periods were uneventful. He achieved walking by 18 months of age. The child had toe walking and recurrent falls for the last 6 months. He also had waddling gait, difficulty in climbing upstairs, difficulty in gripping, and uncorking a bottle. On examination, he had proximal and distal weakness, Gower’s sign, deltoid hypertrophy, and hyporeflexia. Child was not co-operative for sensory examination. A clinical diagnosis of muscle disease (congenital myopathy and muscular dystrophy) was considered. Creatine phosphokinase was in normal range. His father’s and grandfather’s examination revealed flat foot, distal peripheral sensory loss, and areflexia. Grandfather had been symptomatic from 35 years of age with difficulty in climbing upstairs and distal sensory loss. Nerve conduction studies of child, father, and grandfather showed demyelinating polyneuropathy. Analysis of PMP22 showed heterozygous deletion in exon 1-5 confirming the diagnosis of Charcot Marie Tooth disease 1/hereditary motor sensory neuropathy type 1 (CMT1/HMSN1) The child highlights the poor correlation of clinical and signs of neuropathy in the index child. All the clinical signs such as hyporeflexia, muscle hypertrophy, and proximal weakness suggested a myopathic process. Calf muscle hypertrophy has been described in congenital myopathies (central core and centronuclear), proximal spinal muscle atrophy type 3, and limb girdle muscle dystrophy.1 Uncini et al2 have described a cohort of 6 children with calf hypertrophy with hereditary motor sensory neuropathy type 1. A compensatory work and stretch induced calf, and other muscle hypertrophy has been postulated. The enlargement of muscle bulk is mainly due to hypertrophy of type 1 fibers in contrast to fat accumulation in dystrophic process.3 Hyperexcitability of peripheral nerves may contribute to hypertrophy, which can be electrophysiologically as continuous muscle unit activity on electromyography. Steiner et al have described genetic anticipation in a cohort of 23 families with hereditary motor sensory neuropathy. The mean age disease onset in parents was 41.22 years compared with 12.61 years in children.4 To summarize, although family history of neuropathy clinched the clinical diagnosis, utility of nerve conduction studies in children with progressive muscle weakness cannot be underemphasized in confirming hereditary neuropathies.