Characteristics and management of arachnoid cyst in the pediatric headache clinic setting.

Objective/background: Arachnoid cysts are generally identified incidentally on brain imaging, although they occasionally cause symptoms because of expansion or bleeding. This study aims to describe patients in whom an arachnoid cyst was identified on magnetic resonance imaging (MRI) study performed for the evaluation of headache in a pediatric headache clinic and to highlight the clinical dilemma posed by this finding.

Methods: A retrospective descriptive study design was used. The electronic database of a tertiary pediatric headache clinic was searched for all newly admitted patients with headache who underwent MRI evaluation in 2008-2013. The indications for imaging were based on clinical practice parameters recommended by the Subcommittee of the American Academy of Neurology. Clinical and imaging parameters were collected from the files. Findings were compared between patients with and without an arachnoid cyst.

Results: Of the 250 (31%) of 800 patients who met the inclusion criteria, 11 (4.4%) had an arachnoid cyst. Two patients had a ruptured cyst with midline shifting and a large subdural collection. Both presented with headache, vomiting, phonophobia, and photophobia. In the other 9 asymptomtic patients with an arachnoid cyst, imaging showed only a mild mass effect without midline shifting; their symptoms were considered unrelated to the cyst. The patients with a symptomatic arachnoid cyst were referred for surgery, with good outcome.

Conclusions: Arachnoid cysts are found in a small percentage of brain scans performed for evaluation of headache in the setting of a hospital-based pediatric headache clinic. For the long run in these clinical settings, most of the cysts are asymptomatic. Precise anamnesis, neurologic examination, and imaging performed according to accepted practice guidelines may help clinicians determine if the headache and symptoms are caused by the cyst or if they should seek primary headache diagnosis with overlapping symptoms. The clinical distinction between symptomatic and asymptomatic patients (symptoms that are directly related to the arachnoid cyst) may be difficult. Family history of migraine may help in the diagnosis of asymptomatic patients.