Scuba Diver Australasia + Ocean Planet
IF YOU CAN’T EQUALISE, ABORT
Sinus barotrauma can be very unpleasant
The diver was a 26-year-old woman with approximately 200 lifetime dives.
She did a single, morning dive to a maximum depth of 27 metres. She reported no troubles equalising or other complications during her descent. Approaching her safety stop near the end of the ascent, however, she was struck by a sudden massive headache, nausea and vomiting. She skipped the safety stop and ascended directly to the surface. The headache and vomiting continued on the boat, and she also experienced an onset of what she called dizziness. The crew helped her remove her gear and administered oxygen. After a few minutes with no improvement, the crew recalled the rest of the divers and called emergency medical services (EMS) and the DAN Emergency Hotline.
Further discussion revealed that the dizziness the diver reported was likely true vertigo. Vertigo is characterised by a spinning sensation and is usually accompanied by nausea and vomiting, while dizziness is a sensation of loss of balance.
In a diving context, a sudden onset of vertigo during ascent or descent is suggestive of ear barotrauma, with inner-ear barotrauma (IEBT) being most concerning. Ear pain may or may not be present. Vertigo is also common in cases of inner-ear decompression sickness (IEDCS). Symptom onset for IEDCS is usually not so sudden and dramatic, and the dive profile did not seem to be aggressive enough to immediately suggest IEDCS. Nevertheless, such a diagnosis could not be completely ruled out.
Distinguishing between IEDCS and IEBT can pose a significant diagnostic challenge, but doing so is critical because the two conditions require very different therapeutic approaches, and misdiagnosis and mistreatment could be harmful.
Headaches are a common postdive complaint, often the result of a sinus barotrauma.
Although much rarer, another possible diagnosis was a very bad sinus barotrauma with gas leaking into the cranial cavity (pneumocephalus). The sudden onset of a massive headache associated
with a significant drop in barometric pressure accompanied by nausea, vomiting and vertigo was suggestive of such a rare diagnosis. The diver did report some difficulties equalising and what seemed to have been some sinus pain during descent as well as a sensation of pressure later during ascent. The diver’s recent history of a cold increased the likelihood of a very bad sinus barotrauma. Pneumocephalus is usually diagnosed using imaging, but small amounts of gas can be reabsorbed in a short time. Because of the relatively small window for a positive diagnostic image and the harmful – even fatal – nature of pneumocephalus, ruling it out should be a priority.
The mechanism of injury is assumed to be a reverse block of the sinuses. The presence of mucus and inflammation of mucous membranes are the most common causes of transient sinus blockage. These generally pose no greater risk than inflammation in the mucous membranes of the sinuses, but with the ambient pressure changes involved in diving, a partial or intermittent blockage may act as a valve that impairs normal gas flow in the sinuses.
Gas expansion from a reverse block can be significant enough to disrupt the thin bone walls separating the sinuses from each other and from the cranial cavity. When a sinus cavity suddenly relieves its pressure into another one, this usually manifests as pain, a headache and possibly a nose bleed. Gas leaking into the cranial cavity (pneumocephalus), on the other hand, can result in anything from headaches to life-threatening neurological deficits.
Potential consequences will depend on the amount of gas and the degree of displacement of normal anatomical structures.
This sort of injury can initially manifest as a moderate or severe headache or, in severe cases, result in seizures or even death. Most cases of pneumocephalus resolve spontaneously without surgical intervention. Management involves breathing oxygen, keeping the head of the bed elevated, taking antibiotics (especially when traumatic injury is involved), managing pain and performing frequent neurologic checks and repeated CT scans.
EVALUATION AND TREATMENT
The diver’s X-rays revealed subtle signs that could indicate pneumocephalus, which warranted admission to the hospital. These findings, however, could not be reproduced during a CT scan several hours later. These diagnostic discrepancies prompted some discussions, but based on the case history, symptom presentation and initial imaging, the diagnosis was still thought to be pneumocephalus following sinus barotrauma. The patient had been breathing pure oxygen since surfacing, including during transportation, evaluation and hospital admission, which could have sped up the reabsorption of the gas.
In the absence of concrete evidence of pneumocephalus, the treatment plan was for the patient to continue to breathe oxygen, begin a course of antibiotics, undergo repeat CT scans and be observed for no less than 48 hours.
A six-month follow-up appointment revealed the diver had a very good outcome and had no complications during or after her hospital stay. She has not resumed diving.
One of the first rules we learn as student divers is to discontinue diving when we experience difficulty equalising. This is probably the first rule we all break. Questions about the use of decongestants are among the most common asked on the DAN Medical Information Line. (Learn more about decongestants and diving at www.DAN.org/medical/FAQ.)
With regard to barotrauma risk, the most critical phases of a dive are