This is a CT Brain Of a 8 years old  boy  who was admitted to the neurology unit because of complaining of Headache and having dizziness lasting from several seconds to one minute in duration for about 5 months duration.They occurred quite infrequently and he was able to resume activity immediately following the episodes. The spell became more frequent and prolonged, and by the time of initial evaluation were occurring 2-3 times per day and lasting 2-3 minutes in duration.

And since last two months he had experienced three episodes of seizure attacks which are more suggestive of  partial seizure according to the given Hx by the patient.
His neurological examination was unremarkable.

What would be the most llikely diagnosis in this patient? 



Arachnoid cyst

Arachnoid cysts are benign cystic lesions localized within the arachnoid membrane that usually contain clear, colorless fluid that is most likely normal cerebrospinal fluid; rarely, they contain xanthochromic fluid.Most are developmental anomalies.But it can also be associated with neoplasms,trauma,surgery and neonatal infections.They are most commonly found in the suprasellar region, sylvian fissure, over the convexity of the hemisphere, and more rarely in the cisterna magna of the posterior fossa.Arachnoid cysts also occur within the spinal canal.
Arachnoid cyst expansion most likely occurs when intracranial pulsation pushes CSF through defects and CSF then becomes entrapped in arachnoid locations.
Arachnoid cysts often are an incidental finding on imaging. Usually, arachnoid cysts are asymptomatic; this is true even of cysts that are quite large. The most commonly associated clinical features are headache, calvarial bulging, and seizures; focal neurologic signs occur less frequently.

  • MRI is the diagnostic procedure of choice because of its ability to demonstrate the exact location, extent, and relationship of the arachnoid cyst to adjacent brain or spinal cord
  • On CT scans, arachnoid cysts are characterized by sharp, nonenhancing borders; they are isodense to CSF
  • Plain radiographic findings are nonspecific and have little to offer in the diagnosis of arachnoid cysts



  1. Anonymous Says:
  2. arachnoid cyst or an old infarct

  3. The scan shows a large left frontoparietal cyst, characterized by a sharp, nonenhancing border. The cyst is isodense to CSF. Based on the symptoms described such as seizures, headaches and dizzy spells, as well as the CT scan, the most likely diagnosis is Arachnoid cyst, which most likely occurred as a congenital anomaly in this case.

  4. drnjenga2001 Says:
  5. Njenga Mburu
    A left sided frontotemporal extra-axial well marginated cystic lesion isodense to CSF. It causes moderate pressure effect to the brain without perilesional oedema leading to frontal horns of the lateral ventricles assymetry. It does not communicate with the ventricular system. No mural nodule or calcification is noted.
    Diagnosisis: Arachnoid cyst
    DDX: Encephalomalacia

  6. arbitarylife Says:
  7. mass occupying lesion in the cranial cavity of cystic nature


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