statdx/docs_md/articles/extraventricular-obstructive-hydrocephalus_a0886d4c-f504-4165-bb52-2400e2385f68.md

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Extraventricular Obstructive Hydrocephalus	a0886d4c-f504-4165-bb52-2400e2385f68	key value a25c450b-3d34-4f64-bba3-cc0834813df6 Miral D. Jhaveri, MD, MBA	name slug treeNodeId Brain brain 6d8829f1-14d7-45af-8675-255189aa526a name slug treeNodeId Diagnosis diagnosis 51c00394-446e-4a38-94af-d3b1d14d34e8 name slug treeNodeId Anatomy-Based Diagnoses anatomy-based-diagnoses 529d3e33-f508-498c-bc70-cf962e81e629 name slug treeNodeId Ventricles and Cisterns ventricles-and-cisterns 33b267f0-908c-4c77-81f8-f6135d1bc592 name slug treeNodeId Hydrocephalus hydrocephalus 9ce86e3b-fab6-4657-9e51-5f47bb1a51b5 name slug treeNodeId Extraventricular Obstructive Hydrocephalus extraventricular-obstructive-hydro- null	Brain	244d0107-0a80-48b5-96b6-e095c226c02a	9	08/20/20	Extraventricular Obstructive Hydrocephalus	Brain, Diagnosis, Anatomy-Based Diagnoses, Ventricles and Cisterns, Hydrocephalus, Extraventricular Obstructive Hydrocephalus	Extraventricular Obstructive Hydrocephalus | STATdx	Extraventricular Obstructive Hydrocephalus	DX	true	Brain Diagnosis Anatomy-Based Diagnoses Ventricles and Cisterns Hydrocephalus Extraventricular Obstructive Hydrocephalus

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title: "Extraventricular Obstructive Hydrocephalus" docid: "a0886d4c-f504-4165-bb52-2400e2385f68" authors:

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KEY FACTS

• Terminology

  • Extraventricular obstructive hydrocephalus (EVOH): Enlarged ventricles due to obstruction located outside ventricular system
  • Synonym: "Communicating" hydrocephalus

• Imaging

  • Impaired absorption of CSF distal to 4th ventricle outlet foramina
  • Ventricular size varies with duration of obstruction
  • All ventricles enlarged with no intraventricular obstructive cause
  • Lateral, 3rd, and 4th ventricles dilated
  • ± periventricular white matter interstitial edema
  • ± abnormal density/intensity of cisternal CSF ± leptomeningeal enhancement

• Top Differential Diagnoses

  • Intraventricular obstructive hydrocephalus
  • Ventricular enlargement 2° to parenchymal loss
  • Normal-pressure hydrocephalus

• Pathology

  • Hemorrhage → fibrosis/obstruction of subarachnoid space - Most common cause of EVOH
  • Other etiologies include suppurative meningitis, neoplastic or inflammatory exudates
  • Subarachnoid hemorrhage (SAH), exudates may fibrose/occlude subarachnoid space, reduce CSF pulsations

• Clinical Issues

  • Headache, papilledema
  • Nausea, vomiting, diplopia (cranial nerve palsy)

• Diagnostic Checklist

  • EVOH: Generalized ventricular enlargement with abnormal density/intensity in basal cisterns ± leptomeningeal enhancement

TERMINOLOGY

• Abbreviations

  • Extraventricular obstructive hydrocephalus (EVOH)

• Synonyms

  • "Communicating" hydrocephalus

• Definitions

  • Enlarged ventricles due to obstruction located outside ventricular system

IMAGING

• General Features

  • Best diagnostic clue

    - Lateral, 3rd, and 4th ventricles all dilated
    - ± abnormal density/intensity of cisternal CSF ± leptomeningeal enhancement
    

  • Location

    - Obstruction distal to 4th ventricle outlet foramina
    

  • Size

    - Bifrontal horn to intracranial diameter ratio > 0.3
    - Temporal horn width > 3 mm
    

  • Morphology

    - All ventricles enlarged
            - Generally proportionate, symmetrical increase
            - No intraventricular obstructive cause
    

• CT Findings

  • NECT

    - Variable ventricular dilatation ± basal cisterns effaced
    - If subarachnoid hemorrhage (SAH), look for hyperdense CSF
    

  • CECT

    - Look for sulcal/cisternal enhancement
    

• MR Findings

  • T1WI

    - "Dirty" CSF, ventricular dilatation
    

  • T2WI

    - Dilated ventricles ± periventricular white matter interstitial edema
    - Effacement of cortical sulci
    - Hypointense CSF-SAH, exudates
    

  • FLAIR

    - ± periventricular white matter interstitial edema better delineated than T2
    

  • T1WI C+

    - ± enhancement of basal cisterns/sulci
            - Meningitis, carcinomatosis, etc.
    

  • 3D CISS/FIESTA - Exquisitely delineates CSF spaces and helps to exclude intraventricular obstruction

• Imaging Recommendations

  • Best imaging tool

    - MR with T1WI C+
    - 3D CISS/FIESTA
    

• Other Modality Findings

  • Isotope cisternography may show ventricular reflux, stasis (EVOH)

DIFFERENTIAL DIAGNOSIS

• Intraventricular Obstructive Hydrocephalus

  • Global/focal enlarged ventricles due to obstruction proximal to 4th ventricle outflow

• Ventricular Enlargement Secondary to Parenchymal Loss

  • Neurodegenerative disease, cerebritis, hypoxia/ischemia
  • Diffuse/focal enlargement of sulci, cisterns

• Normal-Pressure Hydrocephalus

  • Ventricular enlargement with normal CSF pressure
  • Sulci normal/minimally enlarged
  • Progressive dementia, gait disturbance, incontinence

PATHOLOGY

• General Features

  • Etiology

    - Obstruction to CSF flow at level of basal cisterns or arachnoid villi
            - Also reduced CSF pulsations reduce venous resorption of CSF
    - SAH: Most common cause of EVOH
    - Other etiologies include suppurative meningitis, neoplastic inflammatory exudates
            - All lead to subarachnoid scarring, reduced CSF pulsations
    

• Gross Pathologic & Surgical Features

  • Generalized ventricular dilatation
  • SAH, exudates in basal cisterns & convexity sulci
  • Meningeal fibrosis, arachnoid adhesions

CLINICAL ISSUES

• Presentation

  • Most common signs/symptoms

    - Headache, papilledema
    - Nausea, vomiting, diplopia (cranial nerve palsy)
    

• Natural History & Prognosis

  • Usually progressive unless shunted and primary cause treated

• Treatment

  • CSF diversion (shunt); directed to primary cause

DIAGNOSTIC CHECKLIST

• Consider

  • EVOH: Generalized ventricular enlargement with abnormal density/intensity in basal cisterns ± leptomeningeal enhancement

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References

Selected References

1. Capone PM et al: Neuroimaging of normal pressure hydrocephalus and hydrocephalus. Neurol Clin. 38(1):171-83, 2020
2. Farb R et al: Hydrocephalus and CSF disorders. Diseases of the brain, head and neck, spine 2020-3: Diagnostic Imaging. Cham (CH): Springer; 11-24, 2020
3. Fowler JB et al: Ventriculoperitoneal shunt. Treasure Island (FL): StatPearls Publishing, 2020
4. Roth J et al: The added value of magnetic resonance imaging cisternography and ventriculography as a diagnostic aid in pediatric Hydrocephalus. Pediatr Neurosurg. 54(3):165-72, 2019
5. Fink KR et al: Imaging of nontraumatic neuroradiology emergencies. Radiol Clin North Am. 53(4):871-90, 2015
6. Flannery AM et al: Pediatric hydrocephalus: systematic literature review and evidence-based guidelines. Part 1: introduction and methodology. J Neurosurg Pediatr. 14 Suppl 1:3-7, 2014
7. Grunwald IQ et al: Aneurysmal SAH: current management and complications associated with treatment and disease. J Invasive Cardiol. 26(1):30-7, 2014
8. Krähenbühl AK et al: Endoscopic temporal ventriculocisternostomy: an option for the treatment of trapped temporal horns. J Neurosurg Pediatr. 11(5):568-74, 2013
9. McAllister JP 2nd: Pathophysiology of congenital and neonatal hydrocephalus. Semin Fetal Neonatal Med. 17(5):285-94, 2012
10. Feng F et al: Evaluation of radionuclide cerebrospinal fluid scintigraphy as a guide in the management of patients with hydrocephalus. Clin Imaging. 33(2):85-9, 2009
11. Yamada S et al: Visualization of cerebrospinal fluid movement with spin labeling at MR imaging: preliminary results in normal and pathophysiologic conditions. Radiology. 249(2):644-52, 2008
12. Greitz D: Paradigm shift in hydrocephalus research in legacy of Dandy's pioneering work: rationale for third ventriculostomy in communicating hydrocephalus. Childs Nerv Syst. 23(5):487-9, 2007
13. ter Laan M et al: Improvement after treatment of hydrocephalus in aneurysmal subarachnoid haemorrhage: implications for grading and prognosis. Acta Neurochir (Wien). 148(3):325-8; discussion 328, 2006
14. Greitz D: Radiological assessment of hydrocephalus: new theories and implications for therapy. Neurosurg Rev. 27(3):145-65; discussion 166-7, 2004
15. Kehler U et al: Extraventricular intracisternal obstructive hydrocephalus--a hypothesis to explain successful 3rd ventriculostomy in communicating hydrocephalus. Pediatr Neurosurg. 38(2):98-101, 2003
16. Biedert S et al: [Extraventricular obstructive hydrocephalus.] Fortschr Neurol Psychiatr. 62(11):405-8, 1994

Images

Selected Images

Axial NECT shows acute subarachnoid hemorrhage in the basal cisterns and early extraventricular obstructive hydrocephalus with dilatation of all the ventricles and subtle periventricular hypodensity due to interstitial edema.

Axial NECT shows acute subarachnoid hemorrhage in the basal cisterns and early extraventricular obstructive hydrocephalus with dilatation of all the ventricles and subtle periventricular hypodensity due to interstitial edema.

Axial FLAIR MR images (top) in a patient with breast carcinoma leptomeningeal metastasis shows dilatation of the ventricles with mild periventricular interstitial edema . Axial T1 C+ MR (bottom) shows extensive leptomeningeal enhancement along the cerebellar folia.

Axial T2 MR in a 21-year-old patient with a remote history of meningitis shows chronic "compensated" extraventricular communicating hydrocephalus with marked dilatation of the lateral and 3rd ventricles .

Sagittal T1 MR in the same patient shows a patent widened cerebral aqueduct and foramen of Magendie with dilatation of the 4th ventricle . In longstanding "compensated" hydrocephalus, there is no periventricular interstitial edema around the ventricles, as in this case.

Additional Images

Axial T1WI C+ MR demonstrates subtle leptomeningeal enhancement in the left sylvian fissure in this patient with tuberculous meningitis. There is mild dilatation of the lateral ventricles due to extraventricular obstructive hydrocephalus.

Coronal T1WI MR in a toddler with rapid head growth for 4 months shows enlarged ventricular trigone on the left and enlarging subarachnoid spaces at an age when they should be shrinking. MR venography showed occlusion of both transverse sinuses.

Axial NECT shows hyperdense material in the basal cisterns and sylvian fissures in acute subarachnoid hemorrhage. There is early dilatation of the ventricles with mild periventricular edema due to interstitial edema.

Axial NECT shows acute subarachnoid hemorrhage in the basal cisterns and sylvian fissures . There is early extraventricular obstructive hydrocephalus with mild periventricular hypodensity due to interstitial edema.

Axial T1WI C+ MR shows extensive leptomeningeal enhancement of the basal cisterns in neurosarcoidosis . Notice the early communicating hydrocephalus with the dilated 3rd ventricle and temporal horns .