Objective: To study the electrodiagnostic abnormalities in tick paralysis.
Methods: A 7-year-old girl with acute onset proximal muscle weakness and an engorged dog tick attached to her scalp was evaluated.
Results: The routine motor nerve conduction study showed normal compound muscle action potential amplitude. The stimulated jitter analysis of the orbicularis oculi muscle showed normal jitter with no blocking. The quantitative electromyography of the proximal muscles showed decreased mean duration of the motor unit potentials.
Conclusion: We propose toxin-mediated direct skeletal muscle involvement as one of the reasons for muscle weakness in tick paralysis.