Pupillary Dilation
Monitoring of pupilary dilation, change in galvanic skin response of the left and right palmar surfaces of the hands and monitoring of heart rate (collectively known as the stellate ganglion response) was carried out as part of a thorascopic sympathectomy (T2 & T3) for relief of hyperhidrosis (profuse sweating response). Changes in pupil size, changes in galvanic skin response (profuse sweating and temperature increase) and changes in heart rate were monitored in response to electrical stimulation to localize the stellate ganglion (T1) for avoidance during lesioning procedures. Inadvertent lesioning of the T1 ganglion can produce ptosis of the eyelid and inability to constrict the pupil (Horner’s syndrome). Specifically, an 200-microsecond square wave pulse (10.0-45.0 volts; 11.3 stim/sec.) was used to evoke the response. The stimulus was delivered to ganglia using a thorascopic stimulator probe with the return inserted into tissue near the wound retractor. A Grass SD9 constant voltage stimulator was used to generate electrical pulses. For changes in galvanic skin response from the fingers and hands, skin impedance was measured using a Grass impedance meter connected to Ag-AgCl electrode pads attached to the first and third fingers of each hand. Listed below is a summary of intraoperative activities pertinent to monitoring procedures.
08:00- Equipment set-up begins.
08:30 - Electrodes placed on hands. Baseline skin impedance was measured at 90 kohms for the left hand. Pupils punctate bilaterally.
08:40 - Incision left axilla. Left palm dry to touch.
08:50 - Stimulation of the T1 sympathetic ganglion at 35 volts, small dilation of the left pupil observed. Skin impedance from hand reduced from 90 kohms to 28 kohms. T2 sympathetic ganglion is lesioned.
09:00 - Incision right axilla. Right palm dry to the touch. Stimulation to identify the T1 sympathetic ganglion, no response observed from the left pupil at 40.0 volts.
09:10 - Stimulation to identify the T1 sympathetic ganglion at 35 volts, no response observed from the right pupil despite repeated stimulation from 35 to 50 volts. Stimulation of T2 at 35 volts reduces impedance from 102 kohms to 50 kohms.
09:20 - T2 sympathetic ganglion is lesioned.
09:30 - Begin closing, monitoring is discontinued.
Total Time: 1.5 hrs
08:00- Equipment set-up begins.
08:30 - Electrodes placed on hands. Baseline skin impedance was measured at 90 kohms for the left hand. Pupils punctate bilaterally.
08:40 - Incision left axilla. Left palm dry to touch.
08:50 - Stimulation of the T1 sympathetic ganglion at 35 volts, small dilation of the left pupil observed. Skin impedance from hand reduced from 90 kohms to 28 kohms. T2 sympathetic ganglion is lesioned.
09:00 - Incision right axilla. Right palm dry to the touch. Stimulation to identify the T1 sympathetic ganglion, no response observed from the left pupil at 40.0 volts.
09:10 - Stimulation to identify the T1 sympathetic ganglion at 35 volts, no response observed from the right pupil despite repeated stimulation from 35 to 50 volts. Stimulation of T2 at 35 volts reduces impedance from 102 kohms to 50 kohms.
09:20 - T2 sympathetic ganglion is lesioned.
09:30 - Begin closing, monitoring is discontinued.
Total Time: 1.5 hrs