Assessment of the Excitability of Spinal Motoneurons Using Stimulus-response Curves of the Bulbocavernosus Reflex
Condition: Spasticity, Muscle
MeSH terms: Muscle Spasticity
Study type: Observational

Summary: 
      Spasticity is commonly observed in neurological conditions such as Multiple Sclerosis and
      spinal cord injury. "Peripheral" spasticity, concerning in particular the striated muscles of
      the limbs is nowadays well known and studied with clinical scales (Ashworth, Taridieu...) or
      even electrophysiological methods (H-reflex, T-reflex...). However, this spasticity can also
      affect the perineal muscles and more generally the pelvic muscles. However, there is to date
      no validated and standardized method for evaluating this pelvi-perineal spasticity.

      The aim of the study will be to assess the spinal motoneurons excitability by using the
      stimulus-response curves of the bulbocavernosus reflex.
    

Detailed description: 
      Spasticity defined by Lance in 1980 is "a motor disorder characterized by a velocity
      dependent increase in the tonic stretch reflexes (muscle tone) with exaggerated tendon jerks,
      resulting from hyperexcitability of the stretch reflexes as one component of the upper motor
      neuron syndrome". The occurrence of spasticity, which is common in neurology when the
      pyramidal tract is affected, is commonly observed in the "peripheral" striated muscles.
      However, spasticity also concerns the perineal musculature, with "the exaggeration of the
      stretching reflex of the muscles accessible to pelvic touches". Although there are
      measurement scales commonly used in clinical practice, such as the Ashworth and Tardieu
      scales, or electrophysiological instrumental techniques (H reflex , T reflex), there is
      actually no objective and standardized measurement technique for pelvic spasticity. An
      interesting tool could be the bulbocavernosus reflex (BCR) which is a polysynaptic reflex
      with sacral integration. In addition to its diagnostic and topographical value due to its
      sacral integration, BCR could testify, by its modulation, to the control of the alpha motor
      neuron pool. It could therefore allow to assess motoneuronal excitability, whose increase may
      lead in central patients with supra-connal lesions (spinal cord injuries (SCI), multiple
      sclerosis (MS)), to a release of sacral automatism with exacerbation of reflex responses
      whether bladder (detrusor overactivity), sphincter (detrusor-sphincter dysynergia) or rectal
      (rectal overactivity).

      The aim of the study will be to assess the sacral spinal motor neuron excitability using the
      stimulus-response curves of the BCR.

      The investigators will conduct a prospective monocentric observational study in a specialized
      neuro-urology department. The main objective of this study will be to evaluate the spinal
      motoneuron excitability according to the degree of bladder repletion by modelling recruitment
      slopes (stimulus-response curves) of the BCR.

      First of all, the investigators will assess the feasibility of conducting an analysis of BCR
      stimulus-response curves during a perineal electrophysiological exploration performed in a
      diagnostic context in patients referred for urinary, anorectal or genito-sexual disorders.
      BCR will be recorded after electrical stimulation of the dorsal nerve of the penis or the
      dorsal nerve of the clitoris, using a concentric needle electrode inserted into the left and
      then right bulbcavernous muscle. Stimulations will be performed at progressively increasing
      intensities and each response will be recorded. Acquisition will be performed using a Dantec™
      Keypoint® G4 EMG device, Natus®. The initial stimulation intensity will be at the motor
      threshold, i.e. the degree of stimulation that determines a stable latent motor response and
      will then be increased by 10 to 10 mA to obtain the following 4 reflex responses. Once the
      acquisition will be completed, the curves will be analyzed allowing the analysis of the area
      under the curve (AUC) and the construction of the stimulus-response curves.

      In a second step, the investigators will evaluate the possibility of modelling these
      stimulus-response curves after EMG recording using pre-gelled disposable surface electrodes
      placed on the external anal sphincter (EAS) during a cystometry performed in patients
      consulting for urinary disorders. The stimulation technique will be identical as described
      previously. Finally, the modulation of spinal motoneurons excitability according to the
      degree of bladder filling will be assessed by modelling the BCR stimulus-response curves,
      before and during a cystometry.
    

Intervention name(s): Observational study : no intervention
Intervention type(s): Other
Intervention description(s): Observational study : no intervention, only exporting data
Observational model: Other
Time perspective: Prospective
Sampling method: Probability Sample
Study population: 
        Adult patients who will be referred to our specialized neuro-urology service for
        electrophysiological and urodynamic explorations
      
Keywords: Bulbocavernosus reflex; Spasticity assessment; Motoneurone excitability; Stimulus-response curves