Teaching Case

A previously fit and well patient was admitted to our department following a fall. Since the fall, he developed behavioural changes with confusion.

The 89 year old male patient had a previous history of aortic valve replacement and atrial fibrillation. Clinical history and examination were otherwise unremarkable. The patient came to our department after an unwitnessed fall with confusion. No significant neurological signs were seen and routine blood investigations were unremarkable. A chest radiograph was performed as part of a confusion screen and a pelvic radiograph for pain in both hips following the fall. The chest radiograph demonstrated the midline sternotomy and clear lung fields but there were several densely calcified opacities seen throughout the thorax which were projected over the soft tissues. The hip radiograph also demonstrated multiple oval calcified densities. The patient had a CT examination of the head for the confusion which demonstrated ischaemic changes which correlated with the patient’s acute presentation and clinical symptoms but also demonstrated similar multiple calcified densities distributed in the periventricular and corticomedullary regions within the brain. An MRI examination of the brain confirmed these findings. There were no signs of complications of neurocysticerosis such as meningitis, vasculitis or hydrocephalus.

At the final nodular calcified healing stage of neurocysticercosis the lesions are seen as small calcified nodules (dead cysticercus) which do not significantly enhance on CT or MRI examinations. There are 4 pathological stages seen in neurocysticercosis which is caused by the intracranial parasitic infection of the pork tapeworm Taenia solium (pork tapeworm). Humans are definitive hosts following ingestion of the cysticercus larvae from pork or intermediate hosts following ingestion of Taenia eggs deposited on faecally contaminated food. After the egg is ingested, the embryo is released and penetrates the intestinal wall to enter into the circulation. The preferred tissue sites of implantation for the cystic larvae (cysticerci) are the brain, muscles, skin and eyes.
The vesicular stage is the first stage where there is a thin-walled cyst which may have a hyperdense dot seen within it on unenhanced CT examination which is called the protoscolex. The colloidal vesicular stage is the degeneration of the larva which has a ring-enhancing fibrous capsule on enhanced CT examination and is surrounded by oedema. In the third stage, the granular nodular stage, the oedema reduces and the enhancing nodule begins to involute so that by the fourth stage it represents a small shrunken calcified nodule. In the first 3 stages there is a differential diagnosis of several other pathologies including intracerebral abscesses and metastases. In the fourth and final stage, the differential diagnosis for multiple soft tissue calcifications is wide and includes other parasitic infections such as guinea worm which has an irregular coiled appearance, loa loa which is also coiled and typically occurs in web spaces and armillifer which occurs in trunk muscles. In this final stage the calcified nodules are more conspicuous on CT examination rather than on MRI examination which is in contrast to the earlier stages of neurocysticercosis when MRI can identify discrete enhancement, identifies additional lesions and clearly demonstrates oedema associated with the cyst.