Trapped ventricle, also known as isolated ventricle, is a condition in which there is obstruction to the entry and exit path of CSF through the ventricle.
The presentation is that of increased intracranial pressure due to expanded trapped ventricle.
- trapped temporal horn
- trapped fourth ventricle
Obstruction of the ventricular outlet (with continued CSF production) results in cystic dilation of the fourth ventricle and supratentorial hydrocephalus 2.
- choroid plexitis/ventriculitis
- CNS tuberculosis
- haemorrhage obstructing exit pathway
- intracranial masses
- intraventricular cysts
- complication after lateral ventricular shunting 6
The involved ventricle appears as a focally dilated cystic structure that follows CSF signals on respective cross-sectional imaging. The remaining ventricular system may appear normal.
There is transependymal CSF seepage around the trapped ventricle.
Key hole sign may be seen in cases of herniation of trapped fourth ventricle 1.
Treatment and prognosis
Management options include:
- treatment of the cause
- shunting of the trapped ventricle
- 1. Wolfson BJ, Faerber EN, Truex RC. The "keyhole": a sign of herniation of a trapped fourth ventricle and other posterior fossa cysts. AJNR Am J Neuroradiol. 1987;8 (3): 473-7. Pubmed citation
- 2. Zimmerman RA, Bilaniuk LT, Gallo E. Computed tomography of the trapped fourth ventricle. AJR Am J Roentgenol. 1978;130 (3): 503-6. doi:10.2214/ajr.130.3.503 - Pubmed citation
- 3. Kuiper EJ, Vandertop WP. Trapped third ventricle. Acta Neurochir (Wien). 2001;143 (11): 1169-72. doi:10.1007/s007010100009 - Pubmed citation
- 4. Udayakumaran S, Panikar D. Postulating the concept of compensated trapped fourth ventricle: a case-based demonstration with long-term clinicoradiological follow-up. Childs Nerv Syst. 2012;28 (5): 661-4. doi:10.1007/s00381-012-1712-1 - Pubmed citation
- 5. Ferreira M, Nahed BV, Babu MA et-al. Trapped fourth ventricle phenomenon following aneurysm rupture of the posterior circulation: case reports. Neurosurgery. 2012;70 (1): E253-8. doi:10.1227/NEU.0b013e31822abf95 - Pubmed citation
- 6. Ali K, Nannapaneni R, Hamandi K. The isolated fourth ventricle. BMJ Case Rep. 2013;2013 (apr03 1): . doi:10.1136/bcr-2013-008791 - Free text at pubmed - Pubmed citation