Temporal arachnoid cyst compressing the hippocampus

Temporal arachnoid cyst compressing the hippocampus

Asaad El Bakkari^1,&, Najwa Ech-Chrif El-Kettani¹

¹Neuroradiology Department University Hospital Ibn Sina of Rabat, Rabat, Morocco

^&Corresponding author
Asaad El Bakkari, Neuroradiology Department University Hospital Ibn Sina of Rabat, Rabat, Morocco

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Our work is about a girl aged by 7 years old who suffer from chronically generalized epileptic seizures, headache without mental retardation, the MRI show a homogenous well circumscribed extra axial temporal mass with a High T2 signal, Low signal FLAIR without restriction of diffusion who compress the hippocampus (A). Arachnoids cysts are relatively common benign and asymptomatic lesions firstly described by Bright in 1831.They account for 1% of intra cranial masses; they do not differ from the neighboring arachnoid tissue and contains cerebrospinal fluid. It can develop wherever there is an arachnoid tissue, but it tends to be localized in the peri encephalic arachnoid cisterns. The majority of the cysts are asymptomatic. Approximately 5% of patients present symptoms that are usually the result of gradual enlargement resulting in mass effect. Depending on location, arachnoid cysts may cause headaches, seizures, and rarely hemorrhage. The radiological diagnosis is based on CT and MRI usually the arachnoid cyst present as a well circumscribed extra-axial mass with the same density and signal as CSF on CT and MRI respectively. They do not enhance with contrast, the diffusion-weighted imaging fails to reveal restriction of water diffusion, which helps differentiate arachnoid cysts from epidermoid tumors. The treatment may lead to lasting relief of focal neurological deficits; treatment modalities involve endoscopic or open fenestration and shunt placement.

Figure 1: coronal (A) and axial (B) section MRI T2-weighted shows a well circumscribed extra-axial mass with the same high signal as CSF who became low intense in FLAIR-weighted image (C) without a restriction of diffusion (D)