Hyperacute Brain Magnetic Resonance Imaging of Decompression Illness in a Commercial Breath-Hold Diver
Authors: Kiyotaka Kohshi, Yoshitaka Morimatsu, Hideki Tamaki, Tatsuya Ishitake, Petar J. Denoble
DOI / Source: https://doi.org/10.1002/ccr3.2843
Date: 20 March 2020
Reading level: Intermediate
Why This Matters for Freedivers
This case report is a strong warning that repetitive breath-hold diving can, in rare cases, lead to decompression illness with stroke-like symptoms. It also gives a clear action plan: if neurological symptoms appear after repeated dives, treat it as an emergency, start oxygen as soon as possible, and get evaluated quickly—early imaging and early hyperbaric treatment can matter.
Synopsis
Most freedivers think of decompression illness (DCI) as a scuba problem. This paper shows why that’s not always true. It describes a 65-year-old Japanese commercial breath-hold diver (“Ama”) who developed neurological symptoms after a morning of repetitive dives.
His work pattern is intense and very specific: he repeatedly descended passively using a heavy weight to around 10–20 m (or deeper) and then actively swam back up. He had done this kind of diving for more than 30 years without previous problems. On the fourth consecutive day of diving, near the end of the morning shift, he developed slurred speech, numbness/tingling in his right hand, and an unstable gait. Importantly, he did not have chest pain, loss of consciousness, or obvious weakness—this looked like a “mini-stroke” rather than a classic diving incident.
He reached hospital within an hour, and an MRI was done within two hours of symptom onset. The MRI included the sequences that are most sensitive for very early ischemic injury: diffusion-weighted imaging (DWI) and an apparent diffusion coefficient (ADC) map. The images showed two brain lesions: a hyperacute lesion in the pons (brainstem) with DWI changes and low ADC values (a pattern that fits very early ischemia), and another lesion in the parietal white matter that looked older/subacute. The doctors concluded this was consistent with cerebral DCI, likely involving arterial gas embolism-type mechanisms, rather than a typical vascular stroke (there were no major vessel plaques or abnormalities found).
Treatment is also part of the story. The team recommended transfer to a multi-place hyperbaric center, but the diver refused. He was treated in a mono-place chamber with hyperbaric oxygen at 2.0 ATA for 60 minutes plus IV fluids, then continued daily hyperbaric sessions for 7 days. His gait improved by the next day, and he was discharged with mild residual numbness that gradually improved over months. Follow-up MRI months later showed partial resolution of the pontine signal changes.
The authors use this case to highlight three practical points: (1) neurological DCI in breath-hold diving is rare but real and can be serious; (2) DWI + ADC MRI is valuable in the hyperacute stage to identify and “time” lesions and rule out bleeding; and (3) early oxygen (normobaric first aid, then hyperbaric as soon as possible—ideally within hours) is recommended because permanent brain changes can remain even if symptoms improve quickly.
Abstract
Decompression illness in breath-hold diving is a rare dysbaric disease mainly characterized by stroke-like neurological disorders. The early use of diffusion-weighted MRI combined with an apparent diffusion coefficient (ADC) map in suspected cases can help in the early diagnosis and treatment.