Researchers at the University of Melbourne, Australia studied prospectively changes in gait by age in patients with Dravet syndrome. Of 26 patients aged 2 to 34 years, 15 were male and 11 female, mean age 11.6 years; 23 had SCN1A mutations. Children aged 0 to 5 years (N=7) had a normal gait, whereas 5 of 10 aged 6 to 12 years and 8 of 9 children aged 13 years or older had crouch gait. Ataxia was rarely observed in this cohort. Crouch gait is characterized by increased hip and knee flexion and ankle dorsiflexion, weakness in antigravity lower limb muscles, and without hypertonia or spastic cerebral palsy. Physical examination showed with increasing age, a decrease in passive knee extension and hip extension, and an increase in external tibial torsion and pes planovalgus. Increase in hip internal rotation showed no age-related change. The Functional Mobility Scale showed universal independent walking over 5 and 50 m, whereas adolescents and adults showed wide variation in ratings over 500 m, wheelchair use to independent walking. [1]

COMMENT. Some reports estimate that 50% to 60% of Dravet syndrome patients have an ataxic gait [2]. The cause of crouch gait in adolescents with Dravet syndrome in the present study is unclear, and the typical gait abnormality usually referred to as ataxic or spastic was absent. The authors speculate a possible relation to joint problems and planus foot deformity as precursors, and discuss the pros and cons of orthotic and surgical management. The impact of seizures, type of mutation, and anticonvulsants on the development of crouch gait are also suspect. Development of some connective tissue disorders (Dupuytren’s contracture, general joint pain) is linked to treatment with anticonvulsant drugs, especially phenobarbital. [3]