Delayed Neurological Sequelae Successfully Treated with Adjuvant, Prolonged Hyperbaric Oxygen Therapy: Review and Case Report

Abstract

Carbon Monoxide (CO) intoxication is still a leading cause of mortality and morbidity in many countries. Due to the problematic detection in the environment and subtle symptoms, CO intoxication usually goes unrecognized, and both normobaric and hyperbaric oxygen (HBO) treatments are frequently administered with delay. Current knowledge is mainly focused on acute intoxication, while Delayed Neurological Sequelae (DNS) are neglected, especially their treatment. This work details the cases of two patients presenting a few weeks after CO intoxication with severe neurological impairment and a characteristic diffused demyelination at the brain magnetic resonance imaging, posing the diagnosis of DNS. After prolonged treatment with hyperbaric oxygen, combined with intravenous corticosteroids and rehabilitation, the clinical and radiological features of DNS disappeared, and the patients’ neurological status returned to normal. Such rare cases should reinforce a thorough clinical follow-up for CO intoxication victims and promote high-quality studies.

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“…HBO therapy is sometimes performed in patients with DPHL after CO poisoning; some studies have shown its efficacy ( 7 ). However, it remains unclear why HBO is effective in DPHL after CO poisoning.…”

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“…DNS manifestations include neuropsychiatric symptoms such as cognitive deterioration, sphincters incontinence, a parkinsonismlike condition, akinetic mutism, dystonia, neurological focal symptoms, and depression/anxiety (3)(4)(5). The exact mechanism of DNS development and its incidence are still to be defined (6). A significant problem is represented by a lucid interval between the clinical encounter and DNS development, frequently misleading the recognition and hampering correct treatment.…”

“…Further studies are needed to determine whether these patients may benefit from a prolonged observation in the emergency department, admission to the ward, and more timely or intense rehabilitative therapy. Also, the best treatment for DNS is still debated, especially regarding the number of HBO 2 treatments, the exact pressures and duration to be used, and whether HBO 2 should be administered alone or with adjuvants such as antioxidant scavengers or corticosteroids (6). Lee et al prospectively analyzed data collected from a registry established in 2006, including 537 patients, and found no differences in the reduction of poor neurocognitive outcomes among patients who received one, two, or three HBO 2 sessions within 24 h after CO poisoning.…”