Micturitional disturbance in subacute myelo-optico-neuropathy (SMON)

Background: Micturitional disturbance is known to occur in subacute myelo-optico-neuropathy (SMON). However, its pathophysiology is uncertain and few data are available concerning urodynamic findings. We described our results of micturitional histories and urodynamic studies in patients with SMON. Methods: A history of urinary symptoms was obtained from six patients with SMON (two men, four women; age, 49–72 years, mean 60 years; duration of illness, 14–25 years, mean 19 years). All patients underwent urodynamic studies including measurement of post-micturition residuals, urethral pressure profilometry, cystometry and simultaneous sphincter electromyography. Results: All patients had micturitional symptoms including voiding symptoms in four, filling symptoms in four and urge urinary incontinence in a patient. Urodynamic studies revealed an increased maximum urethral closure pressure in two of four patients studied, decreased bladder volume at first sensation in two, detrusor hyperreflexia in three, absent bulbocavernosus reflex in a patient, and none had detrusor-sphincter dyssynergia or post-micturition residuals. Repeated urodynamic study (10 years after initial study) in a patient with detrusor hyperreflexia showed the same findings. Conclusion: Our results indicate that supranuclear pelvic nerve dysfunction to be mainly responsible for the micturitional disturbance in patients with SMON.