Patients affected by multiple sclerosis (MS) often present Lower Urinary Tract Dysfunction, mainly storage 
LUTS, which significantly affects their quality of life. Percutaneous tibial nerve stimulation (PTNS) is widely used in the treatment of non-neurogenic and neurogenic detrusor overactivity (NDO) in multiple sclerosis (MS); however, few studies have studied the outcome of PTNS on neurogenic detrusor underactivity. The International Continence Society has defined DU as a contraction of reduced strength and/or duration, resulting in a failure to achieve complete bladder emptying within a normal time span. This study aims to report the effect of the PTNS on neurogenic detrusor underactivity in Multiple Sclerosis patients

A retrospective study was conducted between January 2019 and  March 2024. It included all patients who were diagnosed with Multiple Sclerosis, who have detrusor underactivity on Video Urodynamics who were refractory to conservative therapy, and who proceeded with PTNS. Patients with Bladder outlet obstruction and other neurogenic causes of detrusor underactivity and those who discontinued PTNS sessions were excluded. We assessed the number of responders  (Bladder diary, improvement >50% in symptoms) and those who continued beyond 12 sessions to maintenance sessions (12 sessions, a session every other week for 6 sessions, and a monthly session for the other 6 sessions)

A total of 6 patients with Multiple Sclerosis and neurogenic detrusor underactivity were found based on video urodynamics. 4 patients were diagnosed with Relapsing Remitting Multiple Sclerosis (66.6%) and 2 patients with stable Multiple Sclerosis (33.4 %). Age ranged from 38 to 51 years of age (Mean 40.83 +/- 10.46 ). 5 were female (83.3%) and 1 male (16.7%). All the patients had voiding LUTS. One patient had frequency and urgency in addition to retention. One patient was dependent on self-catheterization. All patients received 12 sessions of PTNS. 5 patients (83.3%) patients responded well with improvement >50% and 1 (16.7%) patient did not respond, and who has stable Multiple Sclerosis. The patient who is Self-catheterization dependent abandoned CISC and started to void with PVR< 100 ml. All 5 responders proceeded to 12 maintenance sessions. 4 out of 5 maintained good responses>50% and 1 patient had his symptoms worsened.

This study showed PTNS improved outcomes and quality of life in Multiple Sclerosis patients with detrusor underactivity. The majority of patients went further to 12 maintenance sessions. Interestingly enough, all the Relapsing-Remitting Multiple Sclerosis patients maintained a good response even after the maintenance sessions.

This study suggests that PTNS may have the potential for substantial good outcomes in Multiple Sclerosis patients with detrusor underactivity. Prospective studies of extended duration and larger sample sizes are needed to determine optimal candidates and assess long-term outcomes, & potential complications.