Neurological Consequences of Scuba Diving With Chronic Sinusitis
Sinus barotrauma from scuba diving is relatively common, usually self-limiting, and often the result of transient nasal pathology. We describe serious neurological sequelae occurring in two scuba divers who had chronic sinusitis. We suggest guidelines for evaluating and treating divers who have chronic sinusitis. Divers with nasal or sinus pathology should be aware of the potentially serious consequences associated with scuba diving even after endoscopic sinus surgery to correct this condition.
The two most common medical injuries that can occur as a result of scuba diving are middle ear barotrauma and sinus barotrauma. 1,2 Barotrauma (tissue injury resulting from pressure differences) results from failure of ambient pressure to equalize the pressure in the ears and sinuses. At descent, restricted gas flow into the sinus or ear causes a relative negative pressure, thus inducing an attempt at equalization of the pressure by decreasing the volume of the middle ear or sinus cavity (according to the physical principles known as Boyle's Law). Depending on its magnitude, the pressure difference can cause mucosal edema, contusion, hemorrhage, or separation of the mucosa from the periosteum. Similarly, blockage of the sinus ostium or eustachian tube at ascent may prevent expanding gas from exiting these areas and thus induce the gas to escape injuriously via other pathways.
Most barotraumatic injury of the ear and sinus results from diving with nasal congestion but is self-limiting or requires only analgesic medication. Rare neurological sequelae of sinus barotrauma include cerebral empyema, 3 pneumocephalus, 4 blindness, 5 and involvement of the fifth cranial nerve. 6 In these cases, chronic sinusitis is not thought to be an underlying cause of the barotrauma. In this report, we alert physicians of the serious neurological sequelae that may result from scuba diving with chronic sinusitis and we recommend strategies for avoiding these sequelae.
A 33-year-old commercial diver made a surface-supplied dive to repair a ruptured gas line. At a depth of 55 ft, a mechanical malfunction caused his face mask to become suddenly overpressurized, an event resulting in severe pain in the right ear. Repeated, forceful Valsalva maneuver resulted in severe vertigo and disorientation that resolved within 90 minutes after surfacing. Three days later, he became febrile and lethargic, had severe headache, and was given a diagnosis of pneumococcal meningitis. Despite aggressive treatment, permanent neurological sequelae developed.
The patient's medical history included chronic sinusitis treated with functional endoscopic sinus surgery that included partial bilateral ethmoidectomy and middle meatal antrostomy about 4 months before onset of the meningitis. No surgical complications were reported, and the patient made many dives without difficulty after surgery. A computed tomography (CT) scan taken after surgery (but before onset of meningitis) showed a questionable unilateral defect in the cribriform plate. Because of sinusitis persisting 6 months after meningitis, a second otolaryngologist did complete bilateral ethmoidectomy. No defects were noted in the cribriform plate. Several months after the second surgery, a clear nasal drainage specimen was identified as cerebrospinal fluid. Endoscopic and transcranial repair of a cribriform plate defect corrected this condition.
In a 12-month period during 1993, a 42-year-old navy diver had 5 episodes of loss of vision and facial paralysis on the right side while scuba diving. These symptoms resolved within 30 minutes of surfacing. To avoid the possibility of losing his diving status, he did not seek medical treatment. Forceful Valsalva maneuver was required to equalize pressure in the ears, and blood in the face mask was observed frequently. A long history of recurrent sinusitis (during which time x-ray films documented clouding of one or both maxillary sinuses) was successfully treated by medical therapy, which included cessation of smoking. Three years later, another episode of sinusitis did not respond to medical management. A CT scan showed a 2 × 3-cm mucocele in the middle of the right ethmoid sinus as well as bilateral maxillary and ethmoid sinusitis. Bilateral complete endoscopic ethmoidectomy and middle meatal antrostomy showed hyperplastic granular mucosa in the ethmoid and maxillary sinuses and a mucocele full of creamy, tenacious fluid in the middle of the right ethmoid. The patient was advised that he was still at high risk for sinus and ear barotrauma. Despite this fact, he made more than 100 dives during which the sinuses and ears were cleared with much less difficulty. After a dive in 1990, total sensorineural hearing loss developed in the right ear and resolved spontaneously after 1 month. The next year, total sensorineural hearing loss developed in the left ear and resolved spontaneously after 6 weeks.
Sinus barotrauma is the result of disparate pressure between the nose and sinuses as a result of ostial insufficiency. The sinus ostium may be sufficiently large to permit gradual equalization of pressure when a person is in an aircraft or elevator but may not be able to accommodate the rapidly changing pressure that occurs during scuba diving. Aviational pressure changes are relatively mild compared with those encountered in diving. Every 33-ft depth of seawater represents an additional atmosphere of pressure, whereas an ascent of 18,000 ft from sea level represents a pressure change of only 0.5 atm. For this reason, sinus barotrauma is more commonly observed in divers.
Barotrauma of the sinuses in aviation and diving was reported more than 50 years ago. 7,8 In a series of 50 consecutive patients with sinus barotrauma resulting from diving, Fagan et al. 9 reported that the most common symptom is pain referred to the frontal area, although radiological examination showed that the maxillary sinus was most affected. X-ray films showed mucosal thickening and air/fluid levels. Half of the patients in the series had recent upper respiratory infection or symptoms referable to nasal disease. Most of these divers required no treatment. A more recent study of 50 scuba divers affected with sinus barotrauma described the same presenting symptoms and radiographic findings. 10 Acute sinusitis that developed in 28% of patients in that series prompted the author to suggest use of antibiotics in all patients with symptoms of sinus barotrauma. 10 Another 14% of these patients had preexisting chronic sinusitis, a condition that predisposed the sinuses to recurrent barotrauma. Other than maxillary nerve involvement, neurological complications of sinus barotrauma were not observed. That author speculated that repeated diving may foster permanent sinus mucosal changes or progressive ostial insufficiency. 10 Another study of 76 commercial divers did not, however, show a correlation between sinus changes seen on x-ray films and with length of service. 11
When medical management fails, endoscopic sinus surgery is beneficial for preventing recurrent episodes of barotrauma in aviators 12 or divers 11,13 who have recurrent or chronic sinusitis. If the thin, bony partitions separating the nose and sinuses from the brain and orbit were important in preventing spread of infections from the nose to the eye or central nervous system, then the complications reported here would be much more common. Instead, the important barriers that separate the central nervous system and ocular globe from the nose and sinuses are probably the nasal mucosa, periosteum, and dura.
Both of our patients had a history of chronic sinusitis. An air lock may have formed within the sinuses or nasal cavity, the hyperplastic polypoid mucosa functioning like a ball valve, and both circumstances preventing highly pressurized air inspired at depth from escaping as the patient ascended. Complicating factors included the repeated, forceful Valsalva maneuver by both divers at depth; this maneuver can produce more than 250 mm Hg of pressure and could have forced pus through a small defect in the cribriform plate into the intracranial cavity (in the first diver) and air into the orbit and middle ear (in the second diver). As diver 2 ascended, the air in the orbit and middle ear expanded and compromised blood flow through the retinal artery. Pressurized air in the middle ear thus probably caused the inner ear barotrauma in each diver as well as repeated episodes of facial palsy. 14
We believe it helpful to differentiate between recurrent sinus barotrauma and chronic sinusitis. Patients with recurrent sinus barotrauma may have no clinical or radiological evidence of sinusitis between barotraumatic episodes. Upper respiratory infection, rhinitis, sinusitis, and intranasal pathology (e.g., nasal polyps or septal deviation) are a few factors that can compromise the capacity of the sinus ostia to accommodate the large, rapid pressure changes that occur during scuba dives. Ostial insufficiency always puts patients at risk for development of barotrauma when scuba diving.
When examining patients with recurrent sinus barotrauma, clinicians should first rule out causative pathology by examining the nasal cavities endoscopically and possibly by obtaining a CT scan of the sinuses. Divers with recurrent sinus barotrauma should be advised not to dive with a congested nasal cavity (e.g., during an upper respiratory infection or during an episode of either allergic or nonallergic rhinitis). In addition, intranasal disease (e.g., nasal polyps or septal deviation) in these divers may require correction to avoid compromising the ostiomeatal complex. Divers with persistent difficulty equalizing pressure in the ear and sinuses should be taught methods of equalizing this pressure. These divers should be advised to begin this equalization while at the surface of the water, then to descend slowly (with feet descending first) and to equalize continuously until a depth of 20 ft or more is reached. Those who have persistent difficulty clearing their ears and sinuses should be advised not to dive at all.
Patients who show evidence of chronic sinusitis should be treated with appropriate medical management. If radiological evidence of disease persists, functional endoscopic sinus surgery should be considered. If no clinical or radiological evidence of ostial insufficiency persists, then a pressure test should be conducted either in a hyperbaric chamber or (more practically) in a 14-ft or deeper swimming pool. If no pain develops at this depth, diving may be resumed. However, these patients must be warned that clearing may still be difficult and that this problem could result in disabling or life-threatening injuries. Our experience with several hundred professional divers has taught us that they continue to dive, no matter how sternly they are warned. Under such circumstances, it is best to instruct them on optimal control of their sinus disease and on nonforceful methods of clearing. We reiterate that scuba diving with chronic sinusitis may lead to serious neurological sequelae and that endoscopic sinus surgery may not necessarily obviate these sequelae.
The Medical Editing Department, Kaiser Foundation Research Institute, provided editorial assistance.