Description

A 12-year-old young girl presented with progressively worsening, generalised, chronic daily headaches for nearly 18 months. There were no vomiting, visual or sensory symptoms. Headaches were not associated with any postural variation or symptoms suggestive of intracranial hypertension. She had a history of chronic rhinitis. Concerns were also raised regarding her short-term memory, both by school and parents. She had also been diagnosed with dyslexia.

Head circumference was 65 cm with temporo-parietal bossing. There was no papilloedema and neurological examination was unremarkable.

MRI brain (figure 1) revealed large, bilateral, middle cranial fossa arachnoid cysts, overlying the cerebral hemispheres. She underwent bilateral cyst decompression via burr hole surgery leading to partial improvement in her symptoms.

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Figure 1

T1 weighted coronal view of MRI brain showing large, bilateral, extra-axial arachnoid cysts overlying both cerebral hemispheres, extending into the middle cranial fossa and compressing on the adjacent cerebral hemispheres. There is associated mild scalloping of the overlying calvarium.

Arachnoid cysts are non-tumorous, intra-arachnoid fluid collections and account for 1% of all intracranial space-occupying lesions.1 They are often an incidental finding in children who are scanned for various reasons and more common in boys. Majority are supra-tentorial (90%) and usually detected in the first two decades of life. They can be either primary (congenital) or secondary after trauma, infection or haemorrhage.2

They may be symptomatic as they enlarge and interfere with adjacent structures or cerebrospinal fluid circulation leading to headaches, large head, hydrocephalus, seizures or endocrine problems and cognitive decline, based on the topographical location. Conservative management is recommended, except in rare symptomatic cysts.3