The diver was a 58-year-old male with more than 400 lifetime dives. His only known medical history was hypertension, which was well controlled with a single prescription medication. His general health was good, and he was reasonably physically fit.

The Dive

The diver performed a single boat dive in calm, warm (81°F) water to 80 feet for 30 minutes on air. Neither he nor his buddies experienced any problems during the dive, and they performed a three-minute safety stop at 15 feet. After surfacing they returned to the boat and began to remove their gear.

Within five minutes of being back on board, the diver lost consciousness and collapsed onto the deck. His buddies determined he had a pulse and was breathing on his own. Emergency oxygen was not available, and the two buddies immediately weighed anchor and headed for shore. While en route, one of them called 911. The trip back to the dock took 15 minutes, and an ambulance was there when they arrived. After securing the vessel, the buddies drove to the hospital, just a few minutes behind the ambulance.

The Complication

When the buddies arrived, the emergency-department staff were expeditiously evaluating the diver. He responded only to pain, and his strength on his right side was markedly diminished relative to his left. His left pupil was of normal size and reactive to light; his right pupil was dilated and responded sluggishly to light. He had a strong, regular pulse and spontaneous respirations, but after a short period his respirations began to grow shallower and less regular. When the buddies inquired about their friend's condition they were informed that he was on his way to radiology for a CT scan of his head.

The diver's buddies were disturbed to learn he was not already on his way to a hyperbaric chamber. They were understandably and appropriately concerned that their friend may have sustained an arterial gas embolism (AGE), and they took issue with the doctor's decision to perform a head CT rather than immediately referring the diver to a hyperbaric chamber. Both buddies, independently of one another, contacted DAN®. They each expressed concerns about the loss of time, but both DAN medics explained to the callers that obtaining a head CT was prudent. Despite the buddies' conviction that the diver had sustained an AGE, it was in their friend's best interest to make sure the condition had no other cause. However, the medics' reassurances did not help abate the buddies' fears. They both insisted DAN medics speak to the attending physician to explain that treatment in a chamber was most important. The DAN medics again agreed that AGE was possible, but they reiterated that other causes had to be ruled out.

Diagnosis, Treatment and Recovery

The head CT showed bleeding in the cerebrum — a hemorrhagic stroke — due to a perforated cerebral artery, and the diver was immediately taken into surgery. During surgery, he was found to have a bleeding aneurysm, which is an abnormal weak area in an artery. Aneurysms may be congenital or the result of long-standing, untreated hypertension.

After successful repair, the diver was admitted to the neurological intensive care unit. The initial bleeding caused swelling of the brain, which resolved over the next two weeks. During that period the diver regained consciousness, remained in stable condition and began to recover strength in his right side. He was transferred from the intensive care unit to a rehabilitation facility, where he spent three months undergoing physical and occupational therapy. He recovered enough function in those three months to allow him to return home. Within six weeks of being at home and continuing to undergo therapy, all deficits resolved completely.


Stroke is the third leading cause of death and the leading cause of long-term disability in the United States. While AGE was certainly a consideration in this case, determining the presence or absence of stroke had to take priority. While few clinicians are dive-medicine experts, decompression illness (DCI) is rare and is most often a diagnosis of exclusion, which means it is generally arrived at once other possible diagnoses are ruled out. The need to review alternate explanations of this diver's symptoms was particularly important given the lack of any history of rapid ascent or breath holding. It is very unlikely diving contributed to the rupture of the aneurysm.

It is important to recognize that not all signs and symptoms following dives automatically indicate dive accidents. As this case illustrates, signs and symptoms that suggest DCI may actually represent an entirely different problem. Despite the strong suspicion of AGE in this case, the treating doctor appropriately screened for stroke, the most severe and likely cause that would explain unilateral weakness, pupil dilation and sudden loss of consciousness.

DAN frequently consults with emergency departments and provides dive-medicine information, which can assist clinicians in making accurate diagnoses. DAN is here to help symptomatic divers, their buddies and the health-care professionals who treat them. While prompt treatment of DCI in a hyperbaric chamber is the general goal, ruling out other serious explanations must often take precedence. In this case, delaying surgery by five or more hours could have resulted in persistent neurological deficits. In the end, the goal of medical practice is to apply a thoughtful diagnostic approach to the symptoms present and to determine and effect the most appropriate treatment.

© Alert Diver — Fall 2012