Case Presentation: A four-year-old previously healthy, vaccinated female presented with severe, acute-onset ataxia. She was in her usual state of health until the day prior to presentation, when she was picked up from school and reported feeling like she was going to fall. She continued to develop progressive unsteadiness and experienced several falls throughout the evening. On the morning of presentation, she could not stand or sit up straight unsupported, which prompted her presentation to the emergency department. She denied any pain, changes in mental status or mood, dysphagia, vision changes, diarrhea, rashes, numbness, tingling, or difficulty breathing; though she had a fever, runny nose and congestion four days prior that had since resolved. She lives in a wooded area and plays outside daily. A tick was found on the patient 2 weeks prior that was removed by her sister. Family history was noncontributory. Physical exam on arrival was notable for symmetric loss of deep tendon reflexes throughout and truncal weakness with an inability to sit up for extended periods of time unsupported, but otherwise showed 5/5 strength in bilateral upper and lower extremities, intact sensation and coordination, and normal cranial nerves. There were no signs of ataxia of the upper or lower extremities, but patient was noted to be severely ataxic upon trying to stand and took narrow steps out of proportion to her strength and sensory exam. The remainder of her exam was unremarkable. Extensive lab work-up, including basic metabolic panel, inflammatory markers, cerebrospinal fluid studies, Myasthenia Gravis and Lambert Eaton Panel, and autoimmune encephalopathy panel were negative. Respiratory pathogen panel (RPP) was positive for coronavirus OC43. MRI brain was unrevealing. During sedation for lumbar puncture and MRI, a thorough skin exam revealed an engorged tick attached to the base of the patient’s scalp that was not previously noted. This was removed in its entirety and later identified as a Dermacentor variabilis (the American Dog Tick). Over the subsequent 72 hours following tick removal, patient showed drastic improvement with supportive care alone and was walking independently by the time of discharge three days later. In light of this and the extensive negative work-up, a presumptive diagnosis of tick paralysis was made.
Discussion: Given recent upper respiratory tract symptoms and the positive non-novel coronavirus on RPP, initial suspicion was greatest for an acute cerebellar ataxia. However, the rapid onset of symptoms, areflexia, truncal weakness, and narrow gait resulted in broadening of the differential to consider other entities, including tick paralysis. This prompted the more thorough skin exam under sedation, which revealed the attached tick. Tick paralysis is rare, but progresses to complete paralysis and the mortality rate is up to 12% if untreated or misdiagnosed. Given the overlap of presentation between tick paralysis and other more common neuromuscular and cerebellar conditions, a thorough physical exam should be performed and differential should be expanded if findings are inconsistent with leading differential diagnosis.
Conclusions: A broad differential including tick paralysis should be considered and thorough skin evaluation should be performed for any patient presenting with rapid-onset of ataxia or areflexia and weakness out of proportion to that seen in more commonly encountered diagnoses.