A Case Series of Unilateral Peripheral Neuropathy.

Background And Aims: Peripheral neuropathy may present with a variety of phenotypes depending on the pattern of weakness and sensory loss, the neurophysiological characteristics (axonal or demyelinating) and additional features such as involvement of the autonomic nervous system or the cranial nerves. The most common phenotype is a symmetrical length-dependent sensory and motor neuropathy. Other phenotypes include non-length-dependent forms such as chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) or a sensory neuronopathy or ganglionopathy. Asymmetric forms of neuropathy are mostly represented by mononeuritis multiplex and Lewis-Sumner syndrome or focal CIDP. Unilateral weakness or sensory loss respecting the midline is mainly due to pathology in the central nervous system and is unusual in peripheral neuropathy.

Methods: We evaluated the clinical and genetic features of three unrelated individuals with a peripheral neuropathy affecting one side of the body.

Results: We describe three unrelated patients (two female and one male) with a slowly progressive peripheral neuropathy restricted to one side of the body. Each case is marked by onset in early childhood with the absence of a family history or a structural lesion of the central nervous system. Neurophysiology demonstrated an axonal type of neuropathy in two cases and conduction slowing supportive of a demyelinating neuropathy type in one. Genetic testing was performed in the three cases, specifically looking for variants in genes associated with Charcot-Marie-Tooth disease (CMT) but none were identified in DNA extracted from blood.

Interpretation: A unilateral, slowly progressive peripheral neuropathy is a rare phenomenon, and we propose the cause of this unusual phenotype to be due to a mosaic or chimeric form of Charcot-Marie-Tooth disease (CMT).