Giant Tumefactive Perivascular Spaces: A rare cause of cognitive decline and gait instability

A 54-year-old woman was hospitalized due to cognitive decline, left hemiparesis, gait instability and urinary incontinence that progressed over a year. The patient had a past medical history of Bipolar Disorder.

A brain MRI was performed and T1, T2, FLAIR, DWI, CISS and T1 post-contrast images were taken in axial, sagittal, and coronal planes. In addition, a study of the dynamic of the cerebrospinal fluid (CSF) was done. MR imaging demonstrates multiple and confluent cystlike lesions in the right side of the midbrain, hypointense on axial T1 (Figure 1) and hyperintense on axial T2 (Figure 2), upstream hydrocephalus and slight transependymal edema on axial FLAIR (Figure 3). There is no contrast enhancement (Figure 4) or restricted diffusion (Figure 5). Sagittal CISS (Figure 6) demonstrates obstruction of the cerebral aqueduct, which is corroborated by the study of the dynamic of the CSF (Figure 7).

Background

Perivascular spaces (PVSs) are common interstitial-filled structures, mostly innocent, and when they acquire a dimension >15 mm, are designated as giant tumefactive perivascular spaces. They are pial-lined, interstitial fluid-filled structures that accompany penetrating arteries and are frequently located in the mesencephalothalamic region [4]. They appear in the MRI as cystic-appearing, isointense to CSF in all sequences, without contrast enhancement [2].

Clinical Perspective

Giant tumefactive perivascular spaces are frequently asymptomatic [2]. Rarely they may present with symptoms of hydrocephalus and compression of adjacent brain parenchyma, such as in this case, in which the patient also presented with hemiparesis due to compression of the pyramidal tract.

Imaging Perspective

MRI shows parenchymal cysts isointense relative to CSF in all sequences, without contrast enhancement [3]. Rarely PVSs cause cerebral aqueduct obstruction, with upstream hydrocephalus due to mass effect, as in this case.

Other entities may be easily ruled out by MRI. In neurocysticercosis, MRI demonstrates lesions with several stages, usually less than 1 cm in diameter, starting with a cyst with a dot sign, which becomes an enhancing nodule, that finally becomes calcified.

In CNS cryptococcosis, MRI shows cryptococcomas and leptomeningeal and pachymeningeal enhancement. Cryptococcomas appear in the MRI hypointense in T1, hyperintense in T2/FLAIR, and may have peripheral nodular enhancement. It may also show miliary nodules, choroid plexitis and hydrocephalus.

Neuroglial cysts usually present as isolated lesions, more frequently in the frontal lobe, and follow CSF signal in all sequences. Abscesses present in MRI with restricted diffusion in the DWI sequence with peripheral enhancement and perilesional oedema.

Chronic lacunar infarctions are frequently located in the basal ganglia, thalamus, external or internal capsule and ventral pons, with surrounding gliosis and absence of mass effect.

Outcome

MRI is useful to make the diagnosis, monitor the volume of PVSs and select the cases that can benefit from endoscopic ventriculostomy of the third ventricle, as happened with this patient. Throughout the months following the procedure, the patient had a positive clinical outcome.

Take Home Message

In this patient, because of the chronic and progressive installation of the hydrocephalus, the clinical presentation was similar to a case of normal pressure hydrocephalus.  

The early surgical treatment of hydrocephalus, particularly with a minimally invasive endoscopic procedure such as ventriculostomy, seems to revert part of the symptomatology, even though long-term results are not known [1].