Unusual Case of Spontaneous Cerebral Air Embolism- A report

The introduction of air into cerebral venous or arterial circulation known as cerebral air embolism (CAE), and it  is a rare clinical entity. CAE is commonly iatrogenic secondary to central venous catheter (CVC) placement or removal, various endoscopic procedures, or trauma or surgical scenarios. Doctors from Medanta hospital, Gurugram  report a case of spontaneous CAE in an unusual scenario.

Cerebral air embolism is an uncommon clinical entity. It may be iatrogenic secondary to central venous catheter (CVC) placement or removal, hysteroscopy, laparoscopy, endoscopy, defibrillator placement, and after hemodialysis. Apart from this, cerebral air embolism may occur as a complicating factor in several clinical settings, including thoracic, cardiovascular and neurosurgical operations, and thoracic and cranial trauma.

Neurological symptoms of air embolism include seizures, altered mental status, loss of consciousness, and hemiparesis. In some cases, patients may have sudden onset of a combination of signs and symptoms. Both arterial and venous infarcts may occur as a result of air embolism.

A unique and important property of air that differs from a solid mass embolus is its ability to travel retrograde against the direction of blood flow. This is a result of gas bubbles rising in blood because of their lower specific gravity.

Chronic otitis media is a chronic inflammation of the middle ear and mastoid cavity. Spread of infection from the ear and temporal bone causes intracranial complications. The routes of spread include direct erosion of bone, through normal communication- oval and round windows, vascular channels (thrombophlebitis, periarteriolar spaces of Virchow–Robin), and abnormal preformed pathways- congenital dehiscence and acquired dehiscence (fractures, surgical defect). Extracranial complications are usually direct sequelae of localized acute or chronic inflammation.

Bansal et al describe a case of a  71-year-old man who presented to emergency after developing giddiness following a yoga session which lasted for a few seconds to a minute. After the patient regained consciousness, he had confusion lasting for around 15–20 minutes following which he was able to walk on his own downstairs. The patient had complained of left ear fullness since then. He had a superficial scalp injury due to the fall. There were no associated complaints of pulsatile tinnitus, vomiting, headache, altered behavior, any focal weakness, seizures, or significant hearing loss. On examination, the patient was conscious, oriented, and alert. He did not have any focal weakness or any obvious neurological signs; only tandem walking was impaired.

His MRI brain showed  marked thinning with focal erosion of the left sigmoid plate of the mastoid cavity and mastoid air cells with multiple air foci in the posterior fossa along cerebellar folia, prepontine, and suprasellar cisterns and tracking superiorly along the tentorium cerebelli likely arising from the mastoid cavity through the eroded posterior wall of the left mastoid cavity and sigmoid plate. No definite bony fracture through the mastoid or petrous temporal bone or skull base. The flow void of the transverse and sigmoid sinuses was preserved.A close possibility of hemorrhage in the left cerebellar region was kept as there was significant blooming seen on SWI imaging Thus, plain NCCT head was done which clearly revealed multiple air foci in the posterior fossa along cerebellar folia, prepontine, and suprasellar cisterns and hence the diagnosis of air embolism was established.

In view of the left sigmoid plate dehiscence, HRCT temporal bone was done which corroborated the findings of MRI brain and revealed left otitis media with mastoiditis with cerebral air embolism along bilateral cerebellar folia, prepontine, and suprasellar cisterns. His ENT examination revealed a bilateral intact tympanic membrane and normal ear, nose, and throat examination. The patient was managed conservatively with bed rest, oral antihistamines, and analgesics to which he responded very well.

The chronic otitis media causing  cholesteatoma led to erosion of the left mastoid wall and the sigmoid plate. Air pressure changes during the yoga session possibly led to the leak of air into the cerebellar folia as well as prepontine and suprasellar cisterns. Thiis case highlights to consider cerebral air embolism as a differential diagnosis in such clinical scenarios.

Reference

Bansal R, Bhuyan S, Gupta R, Garg A, Bansal AR. Spontaneous Cerebral Air Embolism–An Unusual Scenario. Neurol India 2023;71:772-4

DOI: 10.4103/0028-3886.383877