Cavernous venous malformation associated with postictal changes: Imaging assessment on an illustrative case

A 45-year-old male with no relevant previous clinical history presented with a tonic-clonic seizure episode, initially refractory to drug treatment. After stabilisation with benzodiazepines, the medical team indicated an imaging assessment. The cerebrospinal fluid (CSF) was negative for infection or other diseases. 

The initial CT demonstrated a left frontal nodular lesion with spontaneous hyperdensity and calcifications. In addition, there was a subcortical white matter hypodensity near the lesion (Fig. 1 to 4).

The subsequent MRI showed the nodular lesion with a classical popcorn-like appearance of the cavernous venous malformation, as also post ictal findings in the nearby middle and inferior left frontal gyrus (Fig. 5 to fig 12). The post-surgery MRI showed haematic material inside the surgical cavity and a partial resolution of the postictal findings, especially the cortical thickening (Fig. 13 to Fig 16).

Cerebral cavernous venous malformations are the third most common cerebral vascular malformation composed of hyalinized dilated thin-walled low-flow capillaries, sometimes with surrounding hemosiderin [1,2].

When symptomatic, these malformations usually manifest in patients around 40 to 60 years with intraparenchymal bleeding or subarachnoid and extra-axial haemorrhage [1,2]. In addition, however, there is an association between cavernous venous malformation and epilepsy [3,4].

At first, CT detected a frontal nodular lesion with calcifications and other hyperintensity areas that could represent haematic material. Succeeding MRI could support the diagnosis, demonstrating a type II Zabramski classification cerebral cavernous malformation with postictal MRI changes in nearby cerebral parenchyma [2,5,6,7].

The cavernous malformation appeared as a classic popcorn-like-lesion, showing T1-hypointensity with hyperintense foci (subacute haematic material) within, T2-hypersignal centrally with surrounding low signal rim, and SWI blooming [2]. In addition, the lesion presented low perfusion on the CBV map, corresponding to the low-flow characteristic of these venous malformations, helping to distinguish from hypervascular lesions.

The middle and inferior left frontal gyrus showed classic postictal changes: swelling and an abnormal corticosubcortical sign, especially with T2 and FLAIR hyperintensity, diffusion restriction of the grey matter, and vasogenic oedema in white matter [5,6,7]. These changes are related to excessive metabolic demands on tissues due to sustained seizure activity, resulting in hypoxia and, if severe enough, cell death [3,4,5].

After the imaging diagnosis, surgery is the treatment of choice in symptomatic cases [4,5]. Afterwards, the patient responded clinically well to the surgery, presenting no seizures. A 72-hour control MRI detected subacute haematic residue inside the surgical cavity, indicating a post-surgery expected finding. In addition, MRI showed a partial reduction of the swelling and hypersignal in FLAIR and T2 of the left frontal middle and inferior gyrus, corroborating the improvement of the postictal changes.

When there are postictal changes in a patient with seizures and a cortical cavernous venous malformation, the neuroradiologist can determine the causal relationship, and the precise imaging diagnosis and surgical treatment established.