Pain assessment in Charcot-Marie-Tooth (CMT) disease.

OBJECTIVE: The objective of our study was to describe and evaluate the prevalence of chronic pain in persons with Charcot-Marie-Tooth (CMT) disease during a multidisciplinary consultation at the Center of Reference for Neuromuscular Diseases.
METHODOLOGY: This prospective study was conducted between 2008 and 2010, it was a partnership between a Center of Reference for Neuromuscular Diseases (Centre de référence des maladies neuromusculaires [CRMD]) and a Department for the Assessment and Treatment of Pain (Département d'évaluation et de traitement de la douleur [DETD]). The evaluation consisted in a complete assessment of each patient during the first multidisciplinary consultation, with a previously established diagnosis validated by genetic testing, by various specialists: neurologist, PM&R physician, pain management specialist and physiotherapist. The evaluation tools used were Visual Analogical Scale (VAS), Hospital Anxiety and Depression Scale (HAD), DN4 scale, Neuropathic Pain Symptom Inventory (NPSI) (if DN4≥4), Pain Questionnaire of Saint Antoine (QDSA) (if DN4<4), body representation to define the painful areas, Overall Neuropathy Limitations Scale (ONLS), Medical Research Council scale (MRC), Short Questionnaire on Pain (QCD), VAS during transfers, self-care, getting dressed and physiotherapy sessions and quantified use of analgesics.
RESULTS: A total of 50 patients were included (28 women, 22 men); two patients (one man and one woman) were discarded from the study because of missing pain assessment data. Mean age was 47years (R: 14-85), in average the symptoms had been present for the past 20years (R: 0.3-68), most patients had little impairment, the mean MRC was 53 (R: 36-60), with CMT1A being predominant (CMT1A: 76.9%, CMTX: 13.5%, CMT2: 5.8%, CMT4: 3.8%). It is noted that 65.4% of patients reported some pain with a mean duration of pain at 140months (R: 5-660). The mean VAS was 5.5 (R: 1-10), greater than 4 in 79.4% of cases, requiring the use of analgesics in 38.4% of cases (step 1: 60%, step 2: 40% on the WHO pain relief ladder). The predominant location of the pain was distal, peripheral and symmetric (64.7%); furthermore the feet were affected in 80% of cases. DN4 was positive in 40.6% of painful patients. In 62.5% of the cases, the pain did not have an underlying mechanical origin. The emotional impact remained quite modest (HAD: A=8; D=5). Patients with CMT1A seemed less affected by pain (P=0.03).
CONCLUSION: This original study describes the pain in patients with CMT disease during a primary multidisciplinary consultation. We see that in 66% of cases, patients do report some pain, this pain is usually moderate, preferentially located in the extremities and is symmetric. In 62.5% of cases, the pain has a neuromuscular origin with a positive DN4 in 50% of cases in this etiology. In our study, patients with CMT1A report less pain than patients with other CMT types. This disease being quite rare (rare disease), the number of patients did not allow us to bring up statistically significant results. The pain must be thoroughly screened for because of its frequency in persons with CMT.