Case courtesy of Dr. Jenny Sanders.
14F woke up this morning and collapsed due to leg weakness while on her way to the bathroom; is able to crawl but can’t walk; has some tingling in her LE. Was in usual state of health the day before. No sig medical or psychiatric history. Had a runny nose two weeks ago. No fevers. Sustained a small abrasion on her R leg from a dog crate 4 days ago, but otherwise no trauma; no back pain. No similar sx in past. Lives in a rural town in Ohio; is home-schooled and never received any vaccinations. No recent travel. No significant family history. No sexual, alcohol or drug history. The family has a dog at home. No sick contacts.
Pertinent exam findings: Anxious but breathing comfortably. No ttp over her spine; 3/5 strength b/l lower extremities; normal sensation; absent reflexes in lower extremities; no clonus –more of a flaccid weakness; downgoing Babinski; can’t stand; +truncal ataxia; normal UE exam; normal cranial nerve exam. Healing abrasion on lateral R leg with an otherwise normal skin/msk exam.
During her ED course, the pt also begins complaining of a feeling of heaviness in her upper extremities.
Differential for this girl’s ascending paralysis:
- Cord compression from trauma/epidural abscess/hematoma
- Guillain-Barré syndrome
- Periodic paralysis (hypoK, hyperK, etc)
- Transverse myelitis
- Tick paralysis
- Botulism (usually begins in cranial nerves)
- Tetanus/strychnine poisoning (usually spastic paralysis)
- Heavy metal and organophosphate poisoning
- Solvent inhalation
- Somatoform disorder/hysteric paralysis
CT head was done and showed a normal brain; did note a soft tissue protrusion over the occiput. If you would do an MR brain/spine, it would show a normal brain and spine.
Re-exam after CT: soft tissue protrusion looks like a skin tag, but on closer exam, is an engorged tick.
Diagnosis: tick paralysis, also known as tick toxicosis. Tick paralysis is caused by a neurotoxin released from the salivary glands of female ticks as they feed; the toxin appears to interfere with Ach release at the neuromuscular junction. The paralysis happens only after 4-5 days of feeding. Presentation is usually as in this case, and may be preceeded by myalgia/fatigue, paresthesias, restlessness. If the tick is not removed, the weakness progresses to the upper extremities and cranial nerves over 24-48 hours, eventually causing death from respiratory failure.
Ref: Edlow JA, McGillicuddy DC. Tick paralysis. Infect Dis Clin North Am. 2008;22:397-413