Pediatric EM, Infectious Disease, Wilderness Medicine

Tick Bites: An Often-Missed Cause of Pediatric Paralysis

In early June, a 6-year-old female presented to the ED with a chief complaint of acute onset lower extremity weakness.

Her father stated that she had been playing normally yesterday but complained that her legs felt "wobbly" once toward the end of the day. Upon waking the next morning, she was unable to stand or ambulate. He carried her to the nearest ED, where she was found to have bilateral motor weakness in the lower extremities.

The presentation of motor weakness in children is often alarming, difficult to characterize, and involves a large differential of uncommon pathologies. The can't-miss diagnoses include spinal cord compression, transverse myelitis, acute cerebellar ataxia, hypokalemic periodic paralysis, poliomyelitis, lead poisoning, and botulism, although the most common cause of acute pediatric paralysis is Guillain-Barré Syndrome.1,2 However, there is an etiology of acute paralysis that can be diagnosed with a physical exam alone and is curable at bedside.

Tick paralysis is a rare but important cause of pediatric paralysis. It is often overlooked or misdiagnosed, most frequently as Guillain-Barré Syndrome (GBS), which can lead to an extensive and invasive workup. If left undiagnosed, tick paralysis can progress to respiratory failure and death. ED providers should maintain a high index of suspicion for tick paralysis when encountering a case of acute paralysis in an otherwise healthy child, particularly in the spring and summer months. A 60-year meta-analysis of tick paralysis in the United States showed that cases were predictably higher during the summer months and in regions of the country where ticks are prevalent.3 Case fatality rates have been reported to be as high as 11%, with the diagnosis in such cases being made at a very late stage or post-mortem.4

Tick paralysis is caused by a neurotoxin produced in the salivary glands of gravid ticks. The neurotoxin causes an acute flaccid paralysis by blocking acetylcholine release at the presynaptic neuromuscular junction.5,6 Paralysis progresses in an ascending fashion and includes loss of reflexes. Most cases occur in children, particularly young females under age 8, because they have long hair that can easily disguise an attached tick. 3 Additionally, children appear to be more susceptible to the toxin than adults due to their lower body mass. 6 Ticks are typically attached for 3-4 days before the development of symptoms.7 Once removed, symptoms are rapidly reversed within hours. 7

The differential diagnosis for acute flaccid paralysis in children is very broad, but tick paralysis can be distinguished from other causes of paralysis in several ways. Spinal cord compression typically involves sensory and urinary or fecal incontinence in addition to motor weakness.13 Botulism typically presents with a descending paralysis in contrast to the ascending paralysis noted in tick paralysis. In addition, botulism is more common in infants.14

Tick paralysis is most commonly misdiagnosed by emergency physicians as GBS, as both present with ascending paralysis and the patient typically appears non-toxic at first.3 Additionally, historical features such as history of recent vaccination or recent viral respiratory or gastrointestinal illness may support the diagnosis of GBS.6 In unvaccinated patients or those from endemic regions, poliomyelitis should be considered. Like tick paralysis, poliomyelitis develops rapidly, usually within 24-48 hours.15 However, patients typically have a high fever at onset, which would be unusual in tick paralysis.8,9 Patients with hypokalemic periodic paralysis present with episodic motor weakness and are more likely to be male, older (late childhood or teenage years), and have an associated trigger, such as exercise, stress, or carbohydrate-rich meals.10 Though rare, weakness can occur with lead poisoning. It is more common in children with underlying sickle cell anemia and presents with other symptoms, such as lethargy, abdominal pain, and behavioral changes.11

For patients with tick attachment greater than 36 hours and location in an endemic area, consider prophylactic doxycycline to prevent the development of Lyme Disease.12 The CDC guidelines for prophylaxis are: one dose of doxycycline 4.4 mg/kg with a maximum of 200 mg..12 Prophylactic treatment should be administered within 72 hours of tick removal.12

Case Conclusion

In the case of this 6-year-old, her father did some research prior to arrival and inquired about tick paralysis. He stated that since the start of quarantine the family had been staying at their cabin in rural Virginia and the kids had been spending a lot of time outdoors. The patient was found to have an engorged tick on her scalp. The tick was removed, and she was observed for signs of improvement in lieu of diagnostic work-up. She regained full use of her legs within a few hours and was discharged home ambulating normally.

Pediatric Paralysis Pearls

  • During the spring and summer months, consider the diagnosis of tick paralysis in any child presenting with acute ascending paralysis.
  • If considering the diagnosis of Guillain-Barre Syndrome, the child should undergo a thorough physical exam to look for ticks. This extra step could prevent an unnecessary invasive workup and reduce mortality.
  • Important historical questions to ask in any child with acute flaccid paralysis include:
    • Onset (days vs. weeks)
    • Recent history of respiratory or gastrointestinal illness
    • Recent immunizations and immunization status
    • Incontinence, sensory deficits, or other signs of cord compression
    • History of fever or infectious symptoms
  • Tick paralysis remains a rare diagnosis. However, it is a simple, curable, and gratifying one to make in the ED. If you don't think of it, you can't diagnose it.

References

  1. Edlow JA, McGillicuddy DC. Tick paralysis. Infect Dis Clin North Am. 2008;22(3):397-vii.
  2. Turgay C, Emine T, Ozlem K, Muhammet SP, Haydar AT. A rare cause of acute flaccid paralysis: Human coronaviruses. J Pediatr Neurosci. 2015;10(3):280-281. doi:10.4103/1817-1745.165716
  3. Diaz JH. A 60-year meta-analysis of tick paralysis in the United States: a predictable, preventable, and often misdiagnosed poisoning. J Med Toxicol. 2010;6(1):15-21
  4. Rose I. A review of tick paralysis. Can Med Assoc J. 1954;70(2):175-176.
  5. Edlow JA. Tick paralysis. Curr Treat Options Neurol. 2010;12(3):167-177.
  6. Felz MW, Smith CD, Swift TR. A six-year-old girl with tick paralysis. N Engl J Med 2000;342:90-94.
  7. Simon LV, West B, McKinney WP. Tick Paralysis. [Updated 2020 Apr 28]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan.
  8. Singhi SC, Sankhyan N, Shah R, Singhi P. Approach to a child with acute flaccid paralysis. Indian J Pediatr. 2012;79(10):1351-1357.
  9. World Health Organization. Acute Flaccid Paralysis Field Manual. Published 2009. Accessed July 30, 2020. 
  10. Statland JM, Fontaine B, Hanna MG, et al. Review of the Diagnosis and Treatment of Periodic Paralysis. Muscle Nerve. 2018;57(4):522-530.
  11. Hauptman M, Bruccoleri R, Woolf AD. An Update on Childhood Lead Poisoning. Clin Pediatr Emerg Med. 2017;18(3):181-192.
  12. CDC. Tick Bite Prophylaxis. Updated May 30, 2019. Accessed July 28, 2020. 
  13. Singleton JM, Hefner M. Spinal Cord Compression. StatPearls. 2020 Jan. 
  14. Van Horn NL, Street M. Infantile Botulism. StatPearls Publishing; 2020 Jan. 
  15. Howard RS. Poliomyelitis and the postpolio syndrome. BMJ. 2005;330(7503):1314-1318. doi:10.1136/bmj.330.7503.1314

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