Makindo Medical Notes

Note: Tick paralysis usually affects children with ascending paralysis. Prompt removal of the engorged tick can lead to dramatic recovery.

About

• Geographic prevalence: Tick paralysis is commonly seen in the United States and Australia.
• High-risk group: Children are most often affected, and recent tick-prone activities (e.g., outdoor excursions) serve as an important clue.
• Animals: It also affects domestic animals and livestock, such as dogs and cattle.
• Tick vectors:
  • In the United States: Dermacentor andersoni and Dermacentor variabilis
  • In Australia: Ixodes holocyclus

Aetiology

• A neurotoxin produced by the tick's salivary glands is injected into the host while the tick feeds.
• The toxin level peaks between the fifth and seventh day of tick attachment, at which point paralysis begins to develop.

Clinical Features

• Progressive paralysis: Symptoms develop within 2-7 days of attachment, often starting with weakness and progressing to ascending paralysis.
• Other symptoms:
  • Paraesthesia (tingling), restlessness, irritability, fatigue, and muscle pain (myalgias).
  • Facial nerve palsy, bulbar palsy, respiratory failure, and hyporeflexia (reduced reflexes).
  • Ophthalmoplegia (paralysis of eye muscles).
• Tick bite location: Ticks are often found on the head, nape of the neck, or other covered areas of the body, so a thorough examination is necessary.

Differential Diagnosis

• Guillain-Barré Syndrome (GBS): Similar presentation with ascending paralysis, though GBS is autoimmune in origin and develops over weeks.

Investigations

• Electromyography (EMG): Typically shows reduced amplitude of compound muscle action potentials, helping to distinguish tick paralysis from other neuromuscular disorders.

Management

• Tick removal: The tick should be removed promptly by grasping it as close to the skin as possible and pulling it in a steady, firm manner. Removal usually results in rapid improvement in symptoms.
• Supportive care: Some patients may require intensive care unit (ICU) support, particularly if respiratory failure develops.
• Prevention: Wearing long trousers and closed-toe shoes, using insect repellents, and performing thorough body checks after being in tick-prone areas can help prevent tick paralysis.