Clinical neurophysiology

Cutaneous silent periods

Cutaneous silent period is a useful, although underestimated tool for the clinical assessment of poly neuropathy as well as other neurological condition. This review provides an up to date on the physiology and methodology for its use in clinical and experimental practice.

In this review the authors deal with the cutaneous silent period (CSP) from different points of view in a comprehensive manner. The first part begins with an extensive review on the different methodologies used for the recordings, such as site of stimulation, intensity and frequency of the stimuli. The techniques are deeply reviewed and the optimal settings as well as the common pitfalls are provided.

The authors then provide an extensive review on the physiological basis of the CSP with special attention to the various mechanisms contributing to the generation of the CSP and its modulation. A nice summary of the spinal and supraspinal circuits of CSP modulation is also given remarking the actual knowledge on  the exact CSP circuitry at the spinal segmental level, including pre- versus post-synaptic inhibition of alpha-motoneurons, interneurons, or corticospinal neurons. 

In the second part, the authors review the pathophysiology of the CSP in different peripheral and central nervous system diseases as well as movement disorders and pain, given the potential utility of CSP for evaluating components of the sensory nerves that are not usually well assessed by the standard electrodiagnostic methods such as centromedullary lesions and small fiber polyneuropathy (especially A-delta). Furthermore, for each pathology a possible physiological explanation is given.

Key points:

  • The articles provide an up to date review of cutaneous silent period
  • Potential CSP applications of clinicaly relevance are given
  • Its use in clinical practice may be useful to explore centromedullary lesions and small fiber polyneuropathy (especially A-delta)
  • Effort should be undertaken to come up with a common standard for routine CSP testing

 

References:

Kofler M, Leis AA, Valls-Solé J. Cutaneous silent periods - Part 1: Update on physiological mechanisms. Clin Neurophysiol. 2019;130(4):588–603. doi:10.1016/j.clinph.2019.01.002

 Kofler M, Leis AA, Valls-Solé J. Cutaneous silent periods - Part 2: Update on pathophysiology and clinical utility. Clin Neurophysiol. 2019;130(4):604–615. doi:10.1016/j.clinph.2019.01.003

Shahani BT, Young RR. Studies of the normal human silent period. In: Desmedt JE, editor. New developments in electromyography and clinical neurophysiology. Basel: Karger; 1973. p. 589–602.