Based upon the history and physical findings of hypo- or arreflexia, muscle wasting, weakness, and sensory deficits in all extremities, the site of the neuroanatomical lesion in this patient is likely to be the peripheral nerve. Lesions affecting roots, motor neuron, or muscle are unlikely to be the sole explanation for this patient's illness. The asymmetry and tempo of dysfunction in this patient would raise the possibility of multifocal nerve involvement, i.e., mononeuropathy multiplex.
Mononeuropathy multiplex refers to dysfunction of two or more discrete nerves.
Usually the onset of symptoms is abrupt in the distribution of one nerve, with subsequent involvement of other nerves at irregular intervals. Infections which commonly involve the nerves are often viral and include HIV and CMV, usually in immunocompromised patients. HIV infection can be associated with peripheral nerve disease either as a direct pathogen, or in relation to drugs given to combat progression of HIV disease. CMV neuropathy is typically the result of opportunistic infection in an immunocompromised host, commonly presenting in an acute or subacute fashion. CMV-associated neuropathy may present as a mononeuropathy multiplex, but more commonly presents as a rapidly progressive symmetric polyneuropathy or polyradiculoneuropathy.