2 The procedure
2.1.1 Overactive bladder syndrome is defined as urinary urgency, with or without urge incontinence, usually with frequency and nocturia. In most cases, the cause of the overactive bladder is unknown. In some cases, it is associated with neurological conditions such as multiple sclerosis or Parkinson's disease.
2.1.2 First-line treatments for OAB include bladder training, pelvic floor muscle training and anticholinergic drugs. Botulinum toxin injection and sacral nerve stimulation may be used in patients for whom conservative treatments have been unsuccessful. More extensive surgical options for treating OAB include bladder reconstruction (such as augmentation cystoplasty) and urinary diversion.
2.2.1 The exact mechanism of action of PTNS on the bladder is unclear, but it is thought to be mediated by retrograde stimulation of the sacral nerve plexus (neuromodulation). The posterior tibial nerve contains mixed sensory motor nerve fibres that originate from the same spinal segments as the nerves to the bladder and pelvic floor.
2.2.2 A fine-gauge needle is inserted percutaneously just above the ankle, next to the tibial nerve, and a surface electrode is placed on the foot. The needle and electrode are connected to a low-voltage stimulator. Stimulation of the posterior tibial nerve produces a typical motor (plantar flexion or fanning of the toes) and sensory (tingling in the ankle, foot or toes) response. Initial treatment usually consists of 12 outpatient sessions lasting 30 minutes each, typically a week apart. Further sessions are generally needed for longer-term relief.
Sections 2.3 and 2.4 describe efficacy and 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 overview .
2.3.1 A randomised controlled trial (RCT) of 220 patients treated by PTNS or sham reported a moderate or marked improvement in overall bladder symptoms in 55% (60/110) and 21% (23/110) of patients respectively at 13-week follow-up (p < 0.001).
2.3.2 An RCT of 100 patients treated by PTNS or medication reported that 80% (35/44) and 55% (23/42) of patients respectively considered themselves to be cured or improved after 12 weeks of therapy (p = 0.01).
2.3.3 A case series of 90 patients reported a subjective response of 64% (58/90) (defined as a patient request for continuous chronic treatment to maintain the response) and an objective response of 57% (34/60) (defined as a reduction of 50% or more in urinary leakage episodes per 24 hours) at 12-week follow-up.
2.3.4 The RCT of 100 patients treated by PTNS or medication reported a significant improvement in quality of life scores in both groups, 12 weeks after treatment.
2.3.5 In a case series of 35 patients, the proportion of patients who were symptom-free decreased from 54% (19/35) immediately after treatment to 23% (8/35) at 1-year follow-up. In a case series of 33 patients who responded to an initial 12 sessions of PTNS and were offered additional treatment sessions at varying intervals for a further 9 months, 94% (30/32) of patients considered themselves to be cured or improved at 6 months and 96% (24/25) at 12-month follow-up.
2.3.6 The Specialist Advisers commented that long-term efficacy has not been established and listed key efficacy outcomes as reduced episodes of urgency and urge incontinence, reduced daily pad usage, and improvements in quality of life and bladder capacity.
2.4.1 In the RCT of 100 patients treated by PTNS or medication, at least 1 'moderate adverse event' considered to be related to the treatment was reported in 16% (8/49) and 14% (7/49) of patients respectively at 12-week follow-up. In the PTNS group, there was 1 report each of generalised swelling (not otherwise described), worsening of incontinence, headache, haematuria, inability to tolerate stimulation, leg cramps, intermittent foot or toe pain and vasovagal response to needle placement within the 12-week follow-up period.
2.4.2 The RCT of 220 patients treated by PTNS or sham reported 7 treatment-related adverse events among the 110 patients treated by PTNS. These were bleeding or discomfort at the needle site (4% [5/110]), and 1 case each of ankle bruising and tingling in the leg.
2.4.3 The Specialist Advisers listed adverse events reported in the literature as minor bleeding, pain and infection at the needle site.