Phrenic Nerve Conduction Testing in Evaluating Demyelinating Neuropathy

Until recently, the technique of phrenic nerve conduction testing has been avoided, possibly because of concerns about technical difficulties. However, in the hands of a practitioner with proper training and some experience, the technique is easy, safe, reproducible, and just as accurate as conduction studies of limb nerves (Muscle Nerve 1995; 18:330). Phrenic nerve conduction testing reveals early respiratory failure in Guillain-Barré syndrome (J Neurol Neurosurg Psychiatry 1996; 60:191). In contrast, patients with hereditary motor and sensory neuropathy type 1 are free of symptoms and signs of respiratory insufficiency, despite considerably prolonged latencies (Muscle Nerve 1992; 15:459). Two patients with multifocal motor neuropathy (MMN…