Clinical presentation of orthostatic tremor (OT) may be misleading and simply perceived by a postural instability such as in several peripheral neuropathies. In addition, peripheral neuropathies represent the leading cause of pathologies associated with OT. Among patients referred for an electroneuromyogram (ENMG) for peripheral neuropathy and presenting with postural unsteadiness, OT assessment will be systematically performed. Demographic, clinical and polygraphy characteristics of these patients will be analyzed and prevalence of OT in the general population of peripheral neuropathies will be assessed.
Among patients who will be referred for ENMG and exploration of a neuropathy, orthostatic tremor will be investigated systematically. Main objective and primary endpoint: * To estimate the prevalence of OT with its 95% confidence interval in the population of patients defined above * Presence of OT confirmed by surface EMG (polygraphy) in patients with standing instability referred for ENMG. Secondary objectives and end points * Determine the demographic, clinical, electrophysiological characteristics of patients with OT; Estimate the prevalence of peripheral neuropathy in patients with OT; Duration of symptoms; Correlation with quantitative neuropathy scores (ISS, MRC, ONLS, R-ODS) * Age, sex, clinical parameters: symptoms reported by the patient (instability, tremor, weakness, pain, falls), duration, current medications, ISS score, MRC score, ONLS score, R-ODS score) and electrophysiological parameters (mean frequency of OT in Hertz, MUNIX score (number of motor units in the anterior tibialis, calculated by software on the ENMG machine).
Study Type
OBSERVATIONAL
Enrollment
100
Patients referred for ENMG to the Clinical Physiology Department and complaining of postural unsteadiness will undergo a polygraphy recording using surface electrodes (Natus Medical Incorporated), performed at the end of ENMG
APHP Lariboisière Hospital, Clinical Physiology Department
Paris, France
RECRUITINGPrevalence of orthostatic tremor (OT
Prevalence of OT (95% confidence interval) in patients complaining of postural instability and referred for ENMG
Time frame: Day 0
Inflammatory Neuropathy Cause and Treatment (INCAT) Sensory Sum Score (ISS) simplified
The ISS ranges from 0 (normal sensation) to 20 (most severe sensory deficit) and is composed of the summation of the following sensation evaluations : pinprick arm grade (range 0-4) ; vibration arm grade (range 0-4) ; pinprick leg grade (range 0-4); vibration leg grade (range 0-4): two-point discrimination grade (range 0-4)
Time frame: Day 0
Medical Research Council (MRC) score
The MRC score grades muscle power on a scale of 0 (no detectable contraction) to 5 (normal force, comparable to the healthy side)
Time frame: Day 0
Overall Neuropathy Limitations Scale (ONLS) score
The ONLS score is be completed by adding the total of the Arm disability scale score (0-5) and Leg disability scale score (0-7) yielding a total score of 0-12 (higher score indicates higher disability)
Time frame: Day 0
Rasch-built Overall Disability Scale (R-ODS) score
R-ODS scale comprising 24 items evaluates the ability to perform daily activities. The answers are rated on a scale of 0 to 48 (with 0 being very poor and 48 being best performance)
Time frame: Day 0
OT frequency
OT frequency in Hz
Time frame: Day 0
Motor unit number index (MUNIX)
MUNIX is a method for assessment of number of motor units using the compound muscle action potential (CMAP) and surface electromyographic interference pattern (SIP).
Time frame: Day 0
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