Thorough Skin Inspection
The answer is D: thorough skin inspection is most likely to reveal the cause of this patient's ascending paralysis following a camping trip.
Clinical Reasoning
This presentation of ascending paralysis starting in the legs and progressing to the arms following outdoor exposure strongly suggests tick-borne paralysis, which is caused by neurotoxins in tick saliva. The key to diagnosis is finding an attached tick, typically in hair-covered areas or skin folds 1.
Why Skin Inspection is Critical
Tick paralysis presents with ascending flaccid paralysis that mimics Guillain-Barré syndrome but has a reversible cause—an attached tick that must be physically identified and removed 1.
The tick is often hidden in inconspicuous locations such as the scalp, behind ears, axillae, groin, or other hair-bearing areas, making thorough inspection essential 2.
Complete skin examination has proven diagnostic value for identifying pathology that would otherwise be missed, with studies showing significant findings in 15-20% of patients when examining beyond the presenting complaint 3.
Why Other Options Are Inadequate
Cardiac auscultation (A) would not identify tick paralysis and is not indicated for ascending motor weakness without cardiac symptoms 2, 4.
Finger-to-nose testing (B) assesses cerebellar function and coordination, which are typically preserved in tick paralysis—this is a lower motor neuron process causing weakness, not ataxia 2.
Optic nystagmus testing (C) evaluates for brainstem or cerebellar pathology (such as in progressive supranuclear palsy), which does not present with acute ascending paralysis after outdoor exposure 2.
Practical Examination Approach
Remove all clothing completely to allow visualization of the entire skin surface, including scalp, interdigital spaces, umbilicus, and perineum 3, 5.
Pay particular attention to hair-covered areas where ticks preferentially attach and remain hidden 2.
Use adequate lighting and systematic inspection from head to toe, as the tick may be small (especially nymphs) and easily overlooked 6, 5.
Critical Clinical Pearl
Removal of the tick results in rapid improvement of paralysis, typically within hours to days, confirming the diagnosis retrospectively. Failure to find and remove the tick can lead to respiratory failure and death 1.