Compensatory hyperhidrosis is excessive sweating of the abdomen, chest, back, thighs, and face,[6,72] usually in response to increased temperature. This is the most common complication following ETS, reported to occur at an average rate of about 60%, with a range of 3% to 98%. Higher rates have been reported from countries with warmer climates, such as in Asia and the Middle East.[46,82] The sweating can be severe for 10% to 40% of patients. Although it has been written that compensatory sweating diminishes with time, several series have documented continued symptoms with longer-term follow-up. In one series of 270 patients followed for a mean of 15 years postsympathectomy, 67% still complained of compensatory sweating, and overall satisfaction fell from an initial level of 96% to 67%. It is possible that patients begin to notice compensatory sweating some time after ETS, as they are initially more aware of the marked reduction of their primary hyperhidrosis.
The mechanism for compensatory sweating is unclear; the most likely explanation is that sweating in the trunk increases to compensate for the lack of sweating from the denervated areas in order to maintain thermoregulation. The occurrence of decreased sweating in other areas not innervated by the ganglia treated by ETS suggests that the response to ETS is more complex. The soles are the most common area with decreased sweating post-ETS, and, along with the axillae and palms, sweating from these areas could be under cortical control, separate from the hypothalamic centers involved in thermoregulation. It has also been proposed that ganglion destruction affects axons of neurons in the interomediolateral spinal cord, which could lead to cell death or re-organization, changing the control of the sympathetic system by the spinal cord and higher, leading to increased sympathetic tone in the other body areas not treated by ETS.
Some studies suggest that the extent of sympathectomy may be related to the incidence of compensatory sweating. Unilateral ETS to treat the dominant hand was associated with a lower incidence of compensatory sweating. Eight of 10 patients who had simple disconnection of the T2 ganglion from the stellate ganglion complained only of mild increased sweating in other body areas. However, in one series there was no difference in incidence of this side effect in groups with T2 and T2-T3 sympathectomy.
Gustatory and phantom sweating, transient post-ETS hyperhidrosis
Several other types of sweating are seen post-ETS for which the etiology is also unclear. Gustatory sweating, or facial sweating due to spicy or other foods, occurs in 17% to 57% of patients.[6,72,82] One explanation for this phenomenon is that aberrant regeneration of sympathetic nerves leads to an anastomosis with the sympathetic trunk and the vagus.[6,82] Another possibility is overactivity of the still-intact or regenerated sympathetic nerve fibers to the face.
Another poorly understood post-ETS phenomenon is phantom sweating, in which patients sense sweat coming out of the skin pores without actual sweating. This occurs in 4% to 48% of patients by 18 months after surgery.[72,106]
Up to a third of patients have several days of increased sweating following initial dryness from day 3 to day 5 after ETS. This phenomenon is thought to be due to degeneration of the postganglionic fibers, which leads to a transient increase in activity of the sweat glands. Patients should be warned in advance of this possibility.
Horner’s syndrome, neuralgia, and cardiac effects
Horner’s syndrome—unilateral upper eyelid ptosis, pupil constriction, and facial anhidrosis—can occur as a temporary post-ETS complication or can be permanent. The incidence of transient Horner’s syndrome can be as high as 0.8%. Permanent Horner’s syndrome occurs in up to 0.1% of cases. Possible causes include an anatomic variation of the stellate ganglion, mistaking the stellate ganglion for the ganglion targeted by ETS, or electric current delivered to the stellate ganglion during electrocautery of the chain below. One group found a much lower rate of Horner’s syndrome when ETS was done with video assistance, presumably because of improved intraoperative visualization.
Neuralgia or pain in the limb denervated by sympathectomy occurs in up to 32% of patients some time after the procedure and is transient. Bilateral T2-T4 sympathectomy reduces the systolic blood pressure without affecting diastolic blood pressure and lowers the heart rate at rest and during exercise.
Recurrence of hyperhidrosis
Recurrence of excessive sweating occurs in about 1% of patients in the first year following the procedure and in about 2% to 5% in subsequent years.[55,72,106] Possible causes for recurrence include an inadequate ablation or resection or nerve regeneration post-ETS. Nerve regeneration has been seen at second operations. Other possible etiologies for recurrence include unrecognized anatomic variations such as residual sympathetic pathways to the affected limb, such as a C8 or T1 contribution to peripheral nerve fibers or a Kuntz nerve.[72,106]
Other surgical complications
Postoperative pneumothorax occurs in 2% to 3% of patients and is less likely when ETS is done with video assistance or smaller thoracoscopes.[127,151,152] Chest tube drainage is needed on occasion. Hemothorax occurred in 0.3% of patients in the largest published series.
Two cases of cardiac arrest during the procedure have been reported, both responding to resuscitation; sympathetic nerve stimulation has been shown to increase the risk for arrhythmia in patients with prolonged QT syndrome.