Taravana, or Taravana syndrome is a disease originally recorded among

Polynesia Polynesia ( , ) is a subregion of Oceania, made up of more than 1,000 islands scattered over the central and southern Pacific Ocean. The indigenous people who inhabit the islands of Polynesia are called Polynesians. They have many things in ...

n island natives and also found among others who habitually dive deep without breathing apparatus many times in close succession, usually for food or

pearl A pearl is a hard, glistening object produced within the soft tissue (specifically the mantle (mollusc), mantle) of a living Exoskeleton, shelled mollusk or another animal, such as fossil conulariids. Just like the shell of a mollusk, a pear ...

s. These free-divers may make 40 to 60 dives a day, each of 30 or 40 metres (100 to 140 feet).

Classification

Taravana appears to be a form of neurological

decompression sickness Decompression sickness (DCS; also called divers' disease, the bends, aerobullosis, and caisson disease) is a medical condition caused by dissolved gases emerging from Solution (chemistry), solution as bubbles inside the body tissues during D ...

. The usual symptoms are

vertigo Vertigo is a condition in which a person has the sensation that they are moving, or that objects around them are moving, when they are not. Often it feels like a spinning or swaying movement. It may be associated with nausea, vomiting, perspira ...

nausea Nausea is a diffuse sensation of unease and discomfort, sometimes perceived as an urge to vomit. It can be a debilitating symptom if prolonged and has been described as placing discomfort on the chest, abdomen, or back of the throat. Over 30 d ...

lethargy Lethargy is a state of tiredness, sleepiness, weariness, fatigue, sluggishness, or lack of energy. It can be accompanied by depression, decreased motivation, or apathy. Lethargy can be a normal response to inadequate sleep, overexertion, overw ...

paralysis Paralysis (: paralyses; also known as plegia) is a loss of Motor skill, motor function in one or more Skeletal muscle, muscles. Paralysis can also be accompanied by a loss of feeling (sensory loss) in the affected area if there is sensory d ...

and

death Death is the end of life; the irreversible cessation of all biological functions that sustain a living organism. Death eventually and inevitably occurs in all organisms. The remains of a former organism normally begin to decompose sh ...

. Scans have confirmed that injury is to the brain.

Presentation

Presentation is usually rapid onset of partial paralysis, visual and hearing problems and difficulties with speech. Occasionally loss of consciousness or death have been recorded.

Causes and mechanism

Taravana is defined as a consequence of multiple repetitive relatively deep breathhold dives, and is considered likely to be due to the formation of nitrogen bubbles in the central nervous system or in the blood, later lodging in the CNS. A fast rate of ascent and short surface interval are thought to be risk factors. There is also a suggestion that blood pooling in the pulmonary circulation due to compression of the lung air content may increase solution of nitrogen into that part of the blood while at depth, which may then be rapidly distributed to the central nervous system at high concentration during ascent, aggravated by a fast ascent rate encouraging bubble formation and growth while still in the systemic arterial circulation.

Diagnosis

History of multiple deep breath-hold dives followed by the typical symptoms. Some symptoms of middle and inner ear barotrauma may be confused, but these are usually accompanied by pain or discomfort in at least one ear.

Etymology

The word ''taravana'' is Tuamotu Polynesian for "to fall crazily". Taravana is also used to describe someone who is "crazy because of the sea".

History

The syndrome was first described in 1956 by a Dr Truc, who had observed neurological disorders in pearl shell divers in the

Tuamotu Islands The Tuamotu Archipelago or the Tuamotu Islands (, officially ) are a French Polynesian chain of just under 80 islands and atolls in the southern Pacific Ocean. They constitute the largest chain of atolls in the world, extending (from northwest to ...

in French Polynesia. He used the term ''taravana,'' meaning "to fall mad", and suggested that it was a form of cerebral decompression sickness.

Treatment

There is no definitive treatment due to lack of reliable case records, but as the condition is hypothesized to be a form of decompression sickness, the available recommendations are to treat it in the same way depending on severity. Oxygen administration at the highest practicable concentration and referral for

hyperbaric oxygen treatment Hyperbaric medicine is medical treatment in which an increase in barometric pressure of typically air or oxygen is used. The immediate effects include reducing the size of gas emboli and raising the partial pressures of the gases present. Initial ...

has been suggested.

Prevention

In the absence of better information, there have been recommendations to use a surface interval of at least three times the duration of the dive.

Epidemiology

The population at risk are those with the greatest capacity for long and deep breath-hold diving, and who make repetitive breath-hold dives with short surface intervals. This population typically dives to hunt and gather in relatively deep water, as these activities depend on maximising bottom time.

Research

Research has shown significant intracardiac bubbling after repetitive breath-hold dives, which supports the hypothesis of a form of decompression sickness, but the current decompression models for ambient pressure diving with breathing apparatus do not reliably predict risk.

References

{{underwater diving, divmed Decompression sickness