Multiple sclerosis causes demyelinating lesions, which can induce multiple symptoms. Ano-rectal avec urinary disorders are frequent due to specific lesions in inhibitor/activator encephalic centers, or interruption on medullary conduction. It seems to be evident that anorectal and urinary disorders are link, because of similar anatomic ways and control process.

To our knowledge several studies test the effect of rectal distension and bladder sensory function but only one study examined the effect of bladder filling on rectal sensitivity on healthy people. The effect of bladder filling on rectal sensory function in patient with neurological disease stay unknown, while dysfunction often occur concomitant, and therapeutic actions in one organ may influence function of the other.

Anorectal manometry is the gold standard for the evaluation of rectal sensory function and the volume of constant sensation to need to defecate is reported in literature as the most reproducible measure.

Primary aim is to assess the effect of need to void on volume of constant sensation to need to defecate in multiple sclerosis with anorectal symptoms. Secondary aim is to identify the effect of need to void on modulation of rectoanal inhibitory reflex (RAIR) and external anal sphincter resting pressure.

Patient with multiple sclerosis over 18 years old, consulting for anorectal disorders in a tertiary center, with an indication to realize an anorectal manometry are included.

History and treatment, height, weight, Expanded Disability Status Scale (EDSS), anorectal and urinary symptoms severity by Bristol, Neurogenic Bowel Dysfunction (NBD), Cleveland, Kess, Urinary Symptom Score (USP) scores, and last urodynamic data are recorded. Patient are asked to drink water until they feel a strong need to void, for which they would go to urinate at home. 3 void volume with portable sonography are done, and the higher is recorded.

Anorectal manometries are realized by the same doctor, in a specific place, with calm. Before the manometric examination, thermal and vibratory sensory thresholds on the right hand are collected. The patient is then placed in a left lateral position. Then the anorectal manometry's catheter is inserted and collect of the external anal sphincter resting pressure begins. Then the investigator proceed to search for RAIR by 5 brief distensions of the intrarectal balloon with increasing volumes of 10 mL from 10 mL to 50 mL. Finally, the investigator collect the threshold volumes of perception, need and maximum tolerable by gradually distending the intra-rectal balloon to 5 mL/s from 0 mL to 300 mL. Toilets are just next to the table of examination.

Next, patient can urinate. 3 post void residual volume with portable sonography are done, and the higher is recorded.

The same tests are realized after urinate, in the same order. After the classical complete manometry was performed.

Primary outcome is the volume of constant sensation to need to defecate Secondary outcomes are the modulation of RAIR and the external anal sphincter resting pressure. Manometric data are collected.

Influence of age, EDSS, severity of symptoms, manometric data and detrusor overactivity on rectal sensory function will be study in secondary analysis.

Inclusion Criteria:

• Multiple sclerosis
• > 18 years old
• Anorectal disorders

Exclusion Criteria:

• full rectal ampullae
• No bladder sensation
• inability to understand simple orders

Patient with multiple sclerosis over 18 years old, consulting for anorectal disorders in a tertiary center, with an indication to realize an anorectal manometry are included.