What Is Cerebral Ischaemia?
Cerebral ischaemia refers to a reduction or interruption of the blood supply to part of the brain, resulting in an inadequate delivery of oxygen and nutrients to nerve cells. Depending on its duration and extent, it may present as a transient ischaemic attack (TIA), without permanent neurological injury, or as an ischaemic stroke, which may result in lasting neurological impairment.
It is one of the leading causes of disability among adults worldwide. Symptoms depend on the area of the brain affected and commonly include hemiplegia or hemiparesis, aphasia, dysarthria, visual deficits, difficulty swallowing, loss of muscle tone and cognitive impairment.
The acute phase requires immediate neurological treatment, such as thrombolysis or mechanical thrombectomy, while management during the chronic phase focuses on achieving the greatest possible recovery of lost function.
Characteristics of Cerebral Ischaemia
A critical concept in cerebral ischaemia is the ischaemic penumbra. Surrounding the necrotic core is an area of brain tissue that is functionally impaired by ischaemia but has not yet undergone irreversible necrosis.
The cells within this area remain viable but inactive. If oxygenation is restored promptly, they may survive and regain function. Without timely restoration of oxygen delivery, they may become incorporated into the necrotic core, increasing the extent of the injury.
During the chronic phase, recovery depends on neuroplasticity—the ability of healthy regions of the brain to assume functions that have been lost. This process requires considerable energy and depends, among other factors, on adequate oxygenation of the peri-lesional tissue where neural reorganization takes place.
Clinical Studies
The use of hyperbaric oxygen therapy in cerebral ischaemia has been studied during both the acute and chronic phases. Clinical studies and experimental evidence from animal models have indicated that hyperoxygenation under pressure may help preserve cells within the ischaemic penumbra during the acute phase.
During the chronic phase, hyperbaric oxygen therapy may improve oxygenation of the peri-lesional tissue and stimulate neurotrophic factors that support neuroplasticity.
Studies involving patients with chronic neurological deficits following an ischaemic stroke have reported improvements in neurological function, motor ability and cognitive performance. These benefits have been observed particularly when treatment was introduced relatively early after the event and combined with an intensive rehabilitation programme.
The Role of Hyperbaric Oxygen Therapy
In cerebral ischaemia, hyperbaric oxygen therapy is used as an adjunctive intervention aimed at preserving viable tissue and creating conditions that support neurological recovery. It never replaces emergency neurological treatment during the acute phase.
During the subacute and chronic phases, its potential value lies in improving oxygenation within the functionally impaired tissue surrounding the ischaemic lesion. Cells that remain inactive because of chronic hypoxia may be reactivated when an adequate oxygen supply is restored.
At the same time, the stimulation of neurotrophic factors, including brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF), may support neuroplasticity and improve the patient’s response to rehabilitation.
A typical treatment course consists of 40 to 60 sessions, combined with physiotherapy, occupational therapy and speech and language therapy.