Complete hemidiaphragmatic paralysis in a patient with multiple sclerosis.

We present a case history of a patient with definite multiple sclerosis who developed an abrupt onset of unilateral diaphragmatic paralysis, minor increase in lower extremity spasticity and complaint of marked neck stiffness. Her vital capacity during this episode was 600 mL and she was in impending respiratory failure. The diaphragmatic paralysis was demonstrated by radiographic plain films and fluoroscopy. Phrenic nerve stimulation was performed during fluoroscopy and the evoked motor response from the diaphragm recorded. There was a normal amplitude diaphragmatic twitch observed with an evoked motor response latency of 1 ms and amplitude of 300 microV. After high dose intravenous steroids, her neck stiffness and spasticity improved, her vital capacity improved to 1500 mL and her diaphragm regained its normal position and movement confirmed by followup radiographic plain films and fluoroscopy. We postulate the presence of a demyelinating plaque in the brainstem fibers descending to the phrenic nucleus as the etiology of the diaphragmatic paralysis. We are unaware of any other case reports of unilateral "upper motor neuron" phrenic nerve paralysis secondary to multiple sclerosis.