PMC8571241_01
(a and b) Axial head computed tomography scan, (c) T2-weighted axial magnetic resonance imaging scan, (d) Axial diffusion weighted magnetic resonance imaging scan. (a) Large right frontal arachnoid cyst with mass effect. (b) Acute hydrocephalus that developed postoperatively with dilation of the lateral and third ventricles. (c) Improvement in hydrocephalus after external ventricular drain placement. (d) No signs of infarction.
SNI-12-533-g001.jpg
PMC8571241_01_SNI-12-533-g001.jpg
F1
Computed tomography (CT) of the head identified a large right frontal AC with mass effect [Figure 1a]. The mental status acutely deteriorated several hours after the procedure, and a head CT demonstrated acute communicating hydrocephalus [Figure 1b]. Subsequent imaging showed improvement in hydrocephalus and pneumocephalus [Figure 1c], but the patient remained obtunded. A stroke work-up including MRI showed no acute infarction [Figure 1d].
PMC8571241_02
(a) Pre-operative head MRI demonstrating a left parietal arachnoid cyst without hydrocephalus. (b) Immediate post-operative CT with no signs of hydrocephalus. (c) Head CT demonstrating acute hydrocephalus during post-operative period. (d) Last follow-up head CT without signs of hydrocephalus.
SNI-12-533-g002.jpg
PMC8571241_02_SNI-12-533-g002.jpg
F2
MRI of the brain revealed a left parietal convexity AC [Figure 2a], and she was referred for neurosurgical evaluation. Intraoperatively, the cyst was found to be under pressure and any adhesions in the subarachnoid space were opened to ensure there was good communication of CSF [Figure 2b]. CT of the head showed acute communicating hydrocephalus [Figure 2c]. Cerebellar hemorrhage was noted on the post-operative CT, but the exact cause is unknown. The latest imaging demonstrated hydrocephalus ex-vacuo of the left lateral ventricle, encephalomalacia of the left parietal lobe, and resolution of the AC [Figure 2d].