Classification of cervical spondylosis or disc protrusion by preoperative evoked spinal electrogram. Follow-up study

The evoked spinal electrogram (SEG) was studied in 11 patients with cervical spondylotic myelopathy or disc protrusion. All the patients were severely handicapped before surgery. The evoked SEG was classified in three grades before and during surgery. Periodic follow-up studies were done at 18 to 35 months, with an average of 24 months. Four of six patients were normal or slightly abnormal SEG recordings showed satisfactory improvement of the disability; however, only one patient showed any improvement when the recording was moderately or severely abnormal. Location of the cord lesion and type of surgery were similar in all patients examined, and the difference was likely ascribed to the physiological change of the intramedullary structures. The evoked SEG provides some information relative to the surgical treatment of spondylotic myelopathy or disc protrusion with cord lesion.

Management of intractable pain in adiposis dolorosa with intravenous administration of lidocaine

Intractable pain in a patient with adiposis dolorosa (Dercum's disease) was treated by IV administration of lidocaine (200 to 400 mg). Relief was maximum 20 minutes after the end of drug infusion and persisted for over 10 hours. Toxicity was minimal. Slow EEG waves which appeared during drug administration disappeared within 20 minutes.

Interactions of human cord dorsum potential

The slow positive wave (P2 wave) of the evoked spinal electrogram was recorded from the posterior epidural space in wakeful man, and studied by applying several modes of peripheral nerve stimulation. With graded stimulation the P2 wave amplitude rapidly reached the maximum at weaker stimulation than that required for the initially positive spikes (P1) and the preceding negative (N1) wave. The "second" component of the P2 appeared during stronger stimulation or during excitemenpt of the subjects. With prolonged repetitive stimulation the P2 wave increased its duration with several summits on the decaying phase. Two interactions were observed between the P2 waves produced by conditioning and testing stimulations in the same or different nerves: inhibition or occlusion by strong stimulation and faciliation by weak stimulation. Thus, the characteristic of the P2 wave in man was similar in part to that of the positive wave observed in decerebrate animals, and differnt in other ways presumably due to influences from supraspinal structures or species differences.

Presynaptic inhibition in man during anesthesia and sleep

The slow positive (P2) wave of the evoked electrospinogram was recorded from the dorsal epidural space in man. The waveform characteristics of the P2 wave were similar to those of the dorsal cord positive wave (P wave), which is believed to be caused by the primary afferent depolarization (PAD) and to be related to presynaptic inhibitory action in animals. The "second" component of the P2 wave appeared during excitement or following strong stimulation and disappeared after thiamylal administration and during natural slow-wave sleep. The second component, also demonstrated in the P wave of rabbits during ketamine anesthesia, was abolished by spinal transection. Therefore, these second components in man and rabbits may originate from a feedback loop via supraspinal structures. Thus, supraspinal influences might play an important role in the regulation of presynaptic inhibition in the spinal cord of man during wakefulness and anesthesia.