This section describes safety outcomes from the published literature that the committee considered as part of the evidence about this procedure. For more detailed information on the evidence, see the interventional procedure overview.
5.1 Transient neuropathy of the left arm with associated muscle weakness after the procedure was reported in 1 patient in a case series of 31 patients. The neuropathy had improved by 6 months, after which the patient was lost to follow-up. Transient median and ulnar neuropathy was described in 1 patient in a case report. After 6 months of rehabilitation, the patient's motor power and sensory deficit had improved but the thenar muscles remained atrophic. Brachial plexus injury was described in 1 patient in a case report. The patient had sensory and motor dysfunction in her fingers, which had not fully recovered after 6 months of rehabilitation.
5.2 Altered sensation in the skin of the upper arm (change in sensitivity, tingling or numbness) was reported in 10% (8/81) of patients who had active microwave ablation (mean duration 67 days) and 3% (1/39) of patients who had a sham treatment (duration 79 days) in a RCT of 120 patients. Temporary numbness was reported in 20% of patients in a case series of 20 patients. Altered sensation in the skin of the axillae was reported in 65% of patients in the case series of 31 patients (median duration 37 days, range 4 days to 4 months). Altered sensation in the skin of the treated limb was reported in 39% (12/31) of patients in the same study (median duration 50 days, range 6 days to 12 months). Loss of sensation in the lateral area of both forearms was reported in 1 patient in a case series of 11 patients. This gradually improved, and the patient recovered fully within 3 months.
5.3 Blisters, burns or ulcerations were reported in 5% (4/81) of patients in the active treatment group (mean duration 28 days, range 12 to 40) and no patients in the sham treatment group in the RCT of 120 patients.
5.4 Axillary bumps or nodules were reported in 3% (2/81) of patients in the active treatment group (mean duration 30 days, range 8 to 52) and 3% (1/39) of patients in the sham treatment group (2 episodes; duration 10 to 12 days). Nodule formation, lasting up to 4 weeks, was reported in 25% of patients in the case series of 20 patients. Palpable bumps under the skin of the axillae was reported in 71% of patients in the case series of 31 patients (median duration 41 days; still present in 2 patients at study exit).
5.5 Compensatory sweating was reported in 3% (2/81) of patients in the active treatment group and no patients in the sham treatment group in the RCT of 120 patients.
5.6 There are several reports on the US Food and Drug Administration's Manufacturer and User Facility Device Experience (MAUDE) website, describing events after microwave ablation for axillary hyperhidrosis. These include nerve damage, infections, abscesses, ulcers, burns, cellulitis, blisters and skin or tissue necrosis. It is not possible to calculate the incidence of these events because the total number of procedures is unknown.
5.7 In addition to safety outcomes reported in the literature, specialist advisers are asked about anecdotal adverse events (events which they have heard about) and about theoretical adverse events (events which they think might possibly happen, even if they have never done so). For this procedure, a specialist adviser described the following anecdotal adverse event: infection. They considered that scarring was a theoretical adverse event.