Proximal weakness of lower limbs as the sole presentation of hyperthyroidism: report of one case

Most children with acute or chronic flaccid limb weakness have a disorder of motor unit. However, it is very important to exclude cerebral or other upper motor neuron disorders before we approach such patients as pure muscle disorders. In general, neuropathy results in distal limb weakness, myopathy manifests with proximal weakness. There are exceptions, however. Accurate diagnosis in this wide array of disorders is dependent on a careful clinical assessment followed by the appropriate investigations. Here we report a 14-year-old girl who presented with progressive difficulty in rising up from the floor for one month. Neurological examination revealed an obese, clumsy but clear girl with stable vital signs. The muscle power of neck and upper limbs was normal. There was positive Gower sign, but the toe and heel gaits were acceptable. The initial blood work and motor/sensory nerve conduction velocity were unremarkable. Further study for thyroid function showed a hyperthyroid state. The proximal myopathy recovered soon after medical treatment. There were no other symptoms, and signs indicating hyperthyroidism and proximal myopathy of lower limbs was the isolated clinical feature. Hyperthyroid myopathy is common in hyperthyroidism, but is unusual as the sole presenting symptom.