[Long-term prognosis of patients with primary myelitic manifestation of tick-borne encephalitis: a trend analysis covering 10 years].

backgroundWhile some studies have been published about the prognosis of the meningitic and encephalitic course of tick-borne encephalitis (TBE), only few data exist about the long-term prognosis of TBE myelitis. The aim of the present prospective study therefore was to investigate such patients over a period of 10 years.

methodIn Baden-Württemberg between 1994 and 1999, 731 patients fell ill with TBE. Of them 81 (11%) suffered from encephalomyelitis. All patients were asked to participate in this study, 57 of whom agreed. Individual impairments were measured by allocating single scores for the paresis of the extremities or cranial nerves, ataxia, impaired consciousness, respiratory paralysis and defective hearing. The total impairment was measured at follow-up investigations at 1, 3, 5 and 10 years.

resultsA total of 11 patients (19%) recovered, 29 (51%) suffered from persisting pareses or other impairments and 17 (30%) died 1-10 years after the acute disease. The most important ameliorations occurred during the first year after the acute disease; thereafter, improvements were lesser and more seldom. The clinical findings after 5 and 10 years correlated well with the status of the acute disease (r=0.8, p<0.01) allowing one to hazard a prognosis at the first presentation. The best restitution was seen for ataxia, impairment of consciousness, double vision, urinary retention and mild paresis of only one extremity (4/5). Patients with tetraparesis and simultaneous occurrence of respiratory paralysis and/or dysphagia, dysarthria or paresis of the neck muscles had the worst prognosis.

conclusionA myelitic course of TBE is associated with the chance to recover in only about 20% of patients. Clinical deficits do not always correlate to findings in magnetic resonance tomography but to observations in postmortem studies.