Decompression Illness (Decompression Sickness Type II)
The most likely diagnosis is decompression illness (DCI), specifically neurological decompression sickness (Type II), given the tingling sensation onset 2 hours post-dive—a classic presentation window for this diving-related emergency 1.
Clinical Reasoning
The timing is pathognomonic: neurological symptoms appearing within hours of surfacing from a dive is the hallmark presentation of decompression illness. According to British Thoracic Society guidelines, decompression illness occurs when inert gas (nitrogen) dissolved in tissues at depth comes out of solution as bubbles during ascent 1. The symptom complex depends on where these bubbles lodge in the systemic circulation.
Key Diagnostic Features Supporting DCI:
- Timing: Symptoms within 2 hours post-dive fits the typical presentation window (symptoms can occur minutes to hours after diving) 2
- Neurological manifestations: Tingling/paresthesias are among the most common neurological symptoms of DCI 1, 3
- Symptom spectrum: DCI neurological symptoms range from paresthesias and sensory changes to focal deficits, weakness, paralysis, or even collapse 1
Pathophysiology:
When bubbles access the systemic circulation (either through intracardiac shunts like patent foramen ovale or when bubble volume overwhelms pulmonary filtration), they travel to tissues causing cardiovascular or neurological abnormalities 1. The exact symptom complex depends on the final resting place of bubbles in the systemic circulation and can range from trivial aches and pains through focal neurological deficits to collapse, convulsions, and death 1.
Critical Management Considerations
This is a medical emergency requiring immediate hyperbaric oxygen therapy. The 5-day delay since symptom onset is concerning and represents suboptimal management. Research demonstrates that prognosis may be improved by rapid recompression 1, and case reports show complete recovery after prompt hyperbaric treatment 3, 4.
Common Pitfalls to Avoid:
Do not dismiss symptoms because they seem mild or delayed: Even "trivial" paresthesias can represent serious DCI requiring treatment 1
Do not wait for symptom progression: The patient in 3 initially had only low back pain and S1 paresthesia but progressed to hemiparesis within 90 minutes—early treatment prevented permanent disability
Do not be falsely reassured by "safe" dive profiles: Studies show neurological DCI can occur even after apparently safe dives that don't exceed no-decompression limits 1, 4
Consider other diagnoses but act quickly: While differential diagnosis should include stroke, spinal pathology, or other neurological emergencies, the diving history makes DCI the primary concern requiring immediate hyperbaric referral 3, 5
Differential Considerations
The 2-hour post-dive timing essentially rules out:
- Pulmonary barotrauma with arterial gas embolism: This presents with neurological symptoms within 5 minutes of surfacing, not 2 hours later 1
- Immersion pulmonary edema: Presents with cough, breathlessness, and hemoptysis during or immediately after the dive 1
Risk Factors That May Be Present:
- Intracardiac shunts (patent foramen ovale, atrial septal defect) increase risk of paradoxical gas embolism 1
- Obstructive airway disease is an independent risk factor for DCI 1
- Smoking history (55% of divers with neurological DCI in one study were smokers) 1
Immediate Action Required
Even 5 days post-symptom onset, this patient requires urgent evaluation for hyperbaric oxygen therapy. Case reports demonstrate benefit even with delayed presentation 3, 4. Contact the nearest hyperbaric facility immediately and arrange emergency transport. Supportive care includes high-flow oxygen, IV hydration, and horizontal positioning during transport.
The persistence of symptoms 5 days later suggests inadequate treatment and potential for permanent neurological sequelae if hyperbaric therapy is further delayed.