Background The mechanisms of nonarticular pain associated with Chikungunya virus (CHIKV) infection are still poorly understood. Many patients that progress to Subacute/Chronic phases have neuropathic pain (NP) besides the articular symptoms. The NP is associated with a less favorable outcome, with greater impact on quality of life and lower efficacy of treatment. The NP can reflect a dysfunction of the nervous system, rather than a neurological lesion induced by CHIKV, but the pathophysiology of the neural disfunction is not completely understood. There are no studies evaluating the electroneurographic findings in patients with CHIKV infection and neuropathic symptoms.
Objectives To evaluate the results of electroneurography (ENoG) of patients with Chikungunya Fever (CF) and neuropathic symptoms.
Methods Patients with diagnosis of CF (clinical and epidemiological) and symptoms of paresthesias underwent ENMG of upper and lower limbs. The electrodiagnostic evaluation consisted of nerve conduction study of median, ulnar, tibial, fibular, sural and plantar nerves. Clinical and epidemiological data were also recorded.
Results The sample was composed by 18 patients (82.3% females) with mean age of 56 (±9.9) years. The mean duration of symptoms of CF at the time of the ENoG was 23.8 (±10.8) weeks and the average of tender and swollen joints (including ankle and foot) was 29.6 (±21.5) and 9 (±9.9), respectively. The mean score of visual analogic scale (VAS) for pain was 4.4 (±2.4) and for fatigue was 5.9 (±2.9), considering values between 0 and 10. No patient presented axial pain and the number of painful joints was higher in upper (19.4±13.9) compared to lower limbs (10.2±8.4). Only 3 patients reported unspecific paresthesias prior to the onset of arbovirosis and worsening after CF. However, these 3 patients had normal ENoG. Six patients had diabetes. Mononeuropathy was the most frequent result occurring in 12 subjects (67%). Bilateral mononeuropathy of median nerve (at carpal tunnel) was found in 11 patients and one subject had median neuropathy just on the left hand. Other mononeuropathies were also present: bilateral tibial nerve in 4, bilateral plantar nerve in 2 and bilateral fibular nerve in 1 patient. Distal axonal polyneuropathy was present in 8 cases (6 sensory and 2 sensorimotor); 5 of these were diabetic. The ENoG was normal in 4 cases. Ten patients were in use of prednisone (mean dose 11.4mg/d) and just 6 were using antineurophatic agents.
Conclusions Our preliminary results indicate that the ENoG is altered in most patients with chronic articular manifestations of CF and associated paresthesias. Mononeuropathy is the most commom finding, even in the chronic phase of the disease when the nonarticular edema is not common. Further clinical studies with a larger number of patients and follow-up tests will be needed to confirm our data.
Andrade DC, Jean S, Clavelou P et al. Chronic pain associated with the Chikungunya Fever: long lasting burden of an acute illness. BMC Infectious Diseases 2010 10:31.
Disclosure of Interest None declared