Can decompression illness (the bends) cause persistent hiccups (intractable singultus)?

Can Decompression Illness Cause Intractable Hiccups?

Yes, decompression illness (the bends) can theoretically cause persistent hiccups through neurological involvement, though this is not listed among the commonly recognized manifestations in diving medicine guidelines.

Understanding Decompression Illness and Its Neurological Manifestations

Decompression illness occurs when dissolved inert gas (primarily nitrogen) forms bubbles during ascent from depth. The clinical manifestations depend entirely on where these bubbles lodge in the systemic circulation 1. According to the British Thoracic Society guidelines, symptoms can include:

• Limb pains ("the bends")
• Fatigue and malaise
• "A wide range of neurological symptoms" ranging from focal deficits to collapse, convulsions, and death 1

The key pathophysiological mechanism is that bubbles can access the systemic circulation through:

• Anatomical shunts (atrial septal defect, patent foramen ovale)
• Intrapulmonary shunts
• Physiological shunts when bubble volume is large 1

The Hiccup Connection: Neuroanatomical Basis

While the diving medicine guidelines do not specifically mention hiccups as a manifestation of decompression illness, recent neurological literature establishes that intractable hiccups are a recognized brainstem pathology symptom 2. The hiccup reflex arc involves:

1. Afferent pathways: phrenic, sympathetic, and vagal nerves
2. Central processing centers: within the brainstem (particularly the dorsal medulla and area postrema)
3. Efferent pathways: phrenic nerve, vagal branches, and intercostal nerves 3

If decompression bubbles embolize to the brainstem structures involved in the hiccup reflex arc, persistent hiccups could theoretically result as part of the "wide range of neurological symptoms" described in decompression illness 1.

Clinical Reasoning and Diagnostic Approach

When evaluating a diver with persistent hiccups after diving:

Immediate considerations:

• Timing is critical: Decompression illness symptoms typically manifest during or shortly after ascent, though delayed presentations can occur 4
• Associated symptoms: Look for other neurological deficits (altered consciousness, focal weakness, sensory changes, visual disturbances) or the classic "limb pains" 1, 4
• Dive profile: Assess depth, duration, ascent rate, and whether decompression stops were missed

Red flags suggesting serious neurological decompression illness:

• Hiccups accompanied by other brainstem signs (dysphagia, dysarthria, ataxia, cranial nerve deficits)
• Altered level of consciousness
• Cardiovascular instability
• Respiratory compromise ("the chokes") 1

Management Priority

If decompression illness is suspected as the cause of persistent hiccups, immediate treatment with hyperbaric oxygen is the definitive therapy 4. Do not delay recompression therapy while investigating other causes of hiccups.

Treatment algorithm:

1. Administer 100% oxygen immediately 4
2. Provide appropriate fluid resuscitation (oral or IV) 4
3. Arrange urgent hyperbaric oxygen therapy 4
4. Perform careful neurological examination to document all deficits
5. Contact diving medicine specialist or hyperbaric facility for consultation

Important Caveats

The absence of hiccups in the standard decompression illness symptom lists 1, 4 suggests this is either:

• An extremely rare manifestation
• Underrecognized in the diving medicine literature
• More commonly attributed to other causes when it occurs

Alternative diagnoses must be considered, particularly if:

• The dive profile was conservative and unlikely to cause decompression illness
• Hiccups are the only symptom without other neurological signs
• Onset is significantly delayed (>24 hours) from the dive

Common non-diving causes of persistent hiccups include gastroesophageal irritation, metabolic disturbances, medications, and other brainstem pathologies 2, 3.

In the context of recent diving with neurological symptoms including hiccups, err on the side of treating for decompression illness given the time-sensitive nature of hyperbaric therapy and the potential for permanent neurological damage if treatment is delayed 4.