Tick paralysis

Background

• Caused by neurotoxin produced by certain ticks (e.g. Ixodes holocyclus) in the US and Australia
• Most cases reported in children

Pathophysiology

• Paralysis results from the neurotoxin “ixobotoxin,” which inhibits the release of acetylcholine at the neuromuscular junction and autonomic ganglia, very similar to botulinum toxin.

Clinical Features

• Symptoms begin 2-6d after attachment of tick
  • Ataxia → symmetric ascending flaccid paralysis with loss of DTRs
• Presentation can be identical to Guillain-Barre including progression to respiratory paralysis
  • Unlike GBS, may have ocular signs (e.g. fixed and dilated pupils)
  • Also unlike GBS, autonomic dysfunction is not typical in tick paralysis

Differential Diagnosis

Tick Borne Illnesses

• Babesiosis
• Colorado tick fever
• Ehrlichiosis
• Heartland virus
• Lyme
• Murine typhus
• Rocky mountain spotted fever
• Southern tick-associated rash illness (STARI)
• Tick paralysis
• Tularemia

Weakness

• Neuromuscular weakness
  • Upper motor neuron:
    • CVA
    • Hemorrhagic stroke
    • Multiple sclerosis
    • Amyotrophic Lateral Sclerosis (ALS) (upper and lower motor neuron)
  • Lower motor neuron:
    • Spinal and bulbar muscular atrophy (Kennedy's syndrome)
  • Spinal cord disease:
    • Infection (Epidural abscess)
    • Infarction/ischemia
    • Trauma (Spinal Cord Syndromes)
    • Inflammation (Transverse Myelitis)
      • Acute flaccid myelitis
    • Degenerative (Spinal muscular atrophy)
    • Tumor
  • Peripheral nerve disease:
    • Guillain-Barre syndrome
    • Toxins (Ciguatera)
    • Tick paralysis
    • Diabetic peripheral neuropathy
  • Neuromuscular junction disease:
    • Myasthenia gravis crisis
    • Botulism
    • Organophosphate toxicity
    • Lambert-Eaton myasthenic syndrome
  • Muscle disease:
    • Rhabdomyolysis
    • Dermatomyositis
    • Polymyositis
    • Alcoholic myopathy
• Non-neuromuscular weakness
  • Can't miss diagnoses:
    • ACS
    • Arrhythmia/Syncope
    • Severe infection/Sepsis
    • Hypoglycemia
    • Periodic paralysis (electrolyte disturbance, K, Mg, Ca)
      • Hypokalemic periodic paralysis
      • Thyrotoxic periodic paralysis
    • Respiratory failure
  • Emergent Diagnoses:
    • Symptomatic Anemia
    • Severe dehydration
    • Hypothyroidism
    • Polypharmacy
    • Malignancy
    • Aortic disease - occlusion, stenosis, dissection
  • Other causes of weakness and paralysis
    • Acute intermittent porphyria (ascending weakness)

Evaluation

• Clinical diagnosis
• Sensory abnormalities and elevation of CSF protein level do not occur
• Progression and resolution of symptoms (with tick removal) is faster than in Guillain-Barre

Management

• Removal of tick is curative, but resolution may take days-weeks.
  • Proper removal of the tick is important.
    • Tick should be grasped as close to the skin surface as possible with blunt curved forceps, tweezers, or gloved hands. Steady pressure without crushing the body should be used. After tick removal, the site should be disinfected.
    • Traditional methods of tick removal using petroleum jelly, topical lidocaine, fingernail polish, isopropyl alcohol, or a hot match head are ineffective and may induce the tick to salivate or regurgitate into the wound.
• Supportive care (resolves on its own)

See Also

• Tick borne illnesses