Kennedy’s disease, or spinal and bulbar muscular atrophy (SBMA), is an X-linked neurodegenerative disease characterised by slowly progressive muscle weakness and atrophy of bulbar, facial and limb muscles accompanied by partial androgen insensitivity. The disease is caused by the expansion of a trinucleotide CAG repeat in the gene encoding the androgen receptor (AR).1 There is no known treatment, although animal studies suggest that androgen deprivation may be of benefit.2 3 In this report, we describe a patient with SBMA who experienced significant worsening of his symptoms during treatment with testosterone, followed by complete reversal to pretreatment functioning on cessation of therapy.

Case history

A now 67-year-old male first presented in 1995 with a 10 year history of difficulty walking. Examination revealed bilateral gynaecomastia and testicular atrophy. Cognitive examination was within normal limits. Examination of cranial nerves revealed fasciculation of the mentalis muscle and fasciculation and mild atrophy of the tongue. In the upper limbs, there was slight wasting of the abductor policis brevis, and absent brachioradialis and triceps reflexes bilaterally, while examination of the lower limbs revealed weakness of the illiopsoas and gastrocnemius muscles bilaterally (grade 4+ out of 5, and 4 out of 5, respectively), absent reflexes throughout and mild sensory loss in a stocking distribution. Nerve conduction studies were consistent with a predominantly motor axonal neuropathy, and electromyography showed widespread denervation. The clinical …