Source:Vedanarayanan VV, Evans OB, Subramony SH. Tick paralysis in children. Electrophysiology and possibility of misdiagnosis.

Of 26 children admitted with acute muscle weakness to the University of Mississippi Medical Center in Jackson over a 5-year period (1992–1997), 6 (ages 3.3 to 5.5 years; 5 girls) were ultimately diagnosed with tick paralysis. The initial diagnosis in 3 of these 6 children was Guillain-Barré syndrome and the clinical and electrodiagnostic findings were indistinguishable from those of tick paralysis. Treatment with IV immunoglobulin was not of benefit. The detection and removal of a tick from the scalp or nape of the neck, followed by a rapid clinical recovery within 24 hours, subsequently established the diagnosis of tick paralysis. Clinical findings included leg, arm, and trunk weakness in 6 patients, areflexia in 5, facial weakness in 4, and bulbar weakness, eye muscle weakness, and respiratory failure in 1 each. Muscles supplied by cranial nerves were normal in 2 patients. Vibratory sense was mildly diminished in the 5 patients tested. Cerebrospinal fluid studies were normal in the 4 tested. Abnormal initial electrodiagnostic studies rapidly returned to normal after removal of the tick and in parallel with clinical improvement.

A child admitted with acute, rapidly progressive muscle weakness should be examined for a tick. The incidence of tick paralysis among children admitted with acute muscle weakness in the series above was ~25%. Failure to consider tick paralysis as a possible cause of muscle weakness may lead to misdiagnosis and inappropriate therapy, since the clinical and electrodiagnostic findings may be difficult to distinguish from those of Guillain-Barré. A search for a tick on the neck or scalp should be routine for any patient presenting with muscle weakness.

The Dermacentor genus of ticks, found throughout North America, causes an illness of milder and shorter duration than the illness caused by the Ixodes holocyclus species that is species that is found in Australia.1 A toxin secreted by the female tick salivary gland is presumed to cause an interference with transmission at motor nerve terminals, which leads to muscle paralysis. Removal of the tick is followed by rapid recovery. Previous reports have cited Guillain-Barré syndrome in the differential diagnosis of tick paralysis.2 The present article emphasizes the similarities of clinical and electrodiagnostic findings. Guillain-Barré syndrome has also been reported in association with Lyme disease3 but is extremely rare. Less common causes of acute paralysis like organophosphate pesticide poisoning and shellfish poisoning should be considered.4 

There is no more cost-effective way to diagnose and treat a problem than with a careful physical exam, accompanied by a knowledgeable differential diagnosis and a pair of tweezers. If, after a lumbar puncture, painful nerve conduction studies, the administration of IVIG and/or plasmapheresis, and perhaps several days in the intensive care unit, discovery of the offending arthropod cures the patient, the family has a right to be ticked off.

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