Clinical History
A 35-year-old woman who recently emigrated from Russia to Belgium, presented with two episodes of left-sided focal motor seizures starting in the upper limb, and spreading to the face and lower limb. She complained of a mild headache over the past week. Neurologic examination revealed weakness of the left extremities.
Imaging Findings
Pre-contrast CT of the head showed a solitary, well-circumscribed 2-cm lesion in the right frontal lobe with a hypodense centre, peripheral hyperdense component, and surrounding oedema. The lesion had peripheral enhancement after contrast administration [Fig. 1].
On subsequent MR imaging, the precentral lesion had a hypo-intense centre on T1W, Pd-T2W and FLAIR images, and a hyperintense rim on T2W and FLAIR images [Fig. 2]. Gadolinium-enhanced MR revealed peripheral rim enhancement of the lesion [Fig. 3]. Surrounding oedema and mild subfalcine herniation was evident. Diffusion-weighted images showed a small restrictive spot in the ventromedial adjacent white matter [Fig. 4].
Discussion
Neurocysticercosis is a common parasitic disease of the human central nervous system. The infection is caused by the larval stage of the tapeworm Taenia solium. Human cysticercosis is transmitted from person to person by fecal-oral contamination. Because of increased migration and travel to endemic areas, the disease is being diagnosed more frequently in developed countries [1].
The clinical presentation is nonspecific and highly variable. The two most common clinical manifestations are epilepsy and intracranial hypertension. However, various neurological symptoms may appear in patients with neurocysticercosis (e.g. focal neurologic deficits, headache and altered mental status).
Lesions of neurocysticercosis can be located in the brain parenchyma, the subarachnoid space, the basilar cisterns, or the ventricles. The parasite causes disease through several mechanisms: mass effect, obstruction, secondary inflammatory changes or residual scarring. As a result, neurocysticercosis has a broad spectrum of radiologic features [2]. The imaging findings depend on the stage of development of the parasite. The embryo is often invisible on CT and MR imaging in the initial, noncystic stage. After several weeks to months cysts will develop containing a scolex (larval head), which sometimes can be recognised on CT or MR imaging with a pathognomonic ‘hole-with-dot appearance’. The cysts measure 5-20 mm and have a thin, smooth wall. The signal intensity of the cysts will be similar to that of CSF on T1W and T2W images. There will be little to no surrounding oedema or contrast enhancement. In later stages, the cysts will retract, form a granulomatous nodule and later calcify. On CT, these cysts may be hyperattenuated with pericystic enhancement after contrast administration as seen in the above-mentioned case. There will be surrounding oedema. Cyst contents are hyperintense on T1W and T2W images, with a thicker wall and ring enhancement on gadolinium-enhanced images. In the calcified stage, there will be no oedema or enhancement [2-3].
In general, the diagnosis is based on neuroimaging and serologic analysis. The treatment is complex and individualised. It includes antiepileptic drugs, cysticidal agents, immunosuppressive agents, and sometimes surgical intervention [1]. The patient in the above-mentioned case underwent surgical removal of the lesion. Microscopic examination confirmed the diagnosis of neurocysticercosis.
Differential Diagnosis List
Parenchymal neurocysticercosis
Tuberculoma
Brain abscess
Neurocysticercosis or other parasitic infection
Primary malignant brain tumour
Metastatic nodule
Final Diagnosis
Parenchymal neurocysticercosis
