Summary and Conclusions

[Stereoelectroencephalography by using O-Arm® and Vertek® passive articulated arm: Technical note and experience of an epilepsy referral centre]

OBJECTIVE

To report a novel, accurate, and safe technique for deep brain electrode implantation to register brain electrical activity or SEEG, using frameless stereotaxy, neuronavigation assisted, and intraoperative CT-guided O-Arm^® and the Vertek^® articulated passive arm.

MATERIAL AND METHODS

All patients implanted by this technique in Barcelona Hospital Clinic were included. A prospective evaluation was made of the accuracy of the technique, as well as complications, surgical time, length of stay, and short-term outcomes.

RESULTS

The study included 10 patients that underwent this procedure. The mean age was 38 years, and 60% were women. A mean of 6.9 (3-10) electrodes/patient, with a total of 69 electrodes, were implanted. The mean time for implantation was 34.7minutes per electrode. The mean distance between the planned target and the final target was 1.39 millimetres (0.95-1.7). There were no surgically derived complications. The epileptogenic zone was determined in 6 cases (60%). Surgical resection was performed in 5 cases (50%), with thermocoagulation in 3 (30%) cases, and in 2 cases (20%) there was no treatment. At a six-month follow-up of the 8 treated cases, 37.5% were ELAI I, 12.5% ELAI III, 25% ELAI IV, and 25% ELAI V.

CONCLUSIONS

The implantation of deep brain electrodes for SEEG by using intraoperative CT O-Arm^® and the Vertek^® articulated passive arm is a safe and effective technique with adequate accuracy.

Dynamic diseases in neurology and psychiatry

Thirty-two (32) periodic diseases of the nervous system are identified in which symptoms and/or signs recur. In 10/32, the recurrence of a symptom complex is one of the defining features of the illness, whereas in 22/32 oscillatory signs occur in the setting of an ongoing nervous system disorder. We discuss the possibility that these disorders may be dynamic diseases. (c) 1995 American Institute of Physics.

Inhibition of experimental seizures in canines by repetitive vagal stimulation

Repetitive electrical stimulation of the canine cervical vagus nerve interrupts or abolishes motor seizures induced by strychnine and tremors induced by pentylenetetrazol (PTZ). Tremors were defined as rhythmic alternating contractions of opposing muscle groups, exerting much less force than seizure contractions. Seizures were induced by injection boluses of strychnine or PTZ at 1- to 4-min intervals until sustained muscle activity was observed electromyographically (EMG). Vagal stimulation terminated seizures in 0.5-5 s. There were prolonged periods with no spontaneous EMG activity after stimulation. The period of protection was approximately four times the stimulation period. The antiseizure actions of vagal stimulation were not altered by transection of the vagus distal to the stimulating electrode. Optimal stimulus parameters were estimated: strength, approximately 20 V (electrode resistance 1-5 omega); frequency 20-30 Hz; duration, approximately 0.2 ms. These data suggest that the antiseizure effects derive from stimulation of small-diameter afferent unmyelinated fibers in the vagus nerve. These results may form the basis of a new therapeutic approach to epilepsy.