An unusual cause of peroneal neuropathy

We discuss the case of a teenage girl who presented with neurologic symptoms suggestive of a peripheral neuropathy, before the development of a central arteriovenous fistula. Electromyography and nerve conduction studies indicated peroneal motor neuropathy, but her comprehensive genetic study results were negative for common Charcot-Marie-Tooth mutations. After 2 years of stable symptoms, she presented with unilateral throbbing headache and tinnitus. Magnetic resonance angiography revealed a carotid cavernous fistula, which was confirmed with conventional angiography. A successful coil embolization of the fistula was performed. Whole exome sequencing demonstrated a de novo heterozygous c.3158G>A (p.G1056D) mutation in the COL31A gene, consistent with Ehlers-Danlos type IV. To our knowledge, this is the first reported case of isolated peroneal motor neuropathy in a patient with Ehlers-Danlos type IV. This case highlights the utility of whole exome sequencing in the diagnosis of patients with neurologic symptoms that do not fit a clear phenotype.