Question 51 / 100
Seizures, Cognitive Deterioration and Incidental Muscle Calcifications
A 47-year-old former construction supervisor is brought to hospital following an episode of collapse associated with rhythmic movements of all four limbs, urinary incontinence and confusion lasting approximately 20 minutes afterwards.
His family reports that he has developed increasing difficulty concentrating, behavioural changes and impaired short-term memory over the preceding 18 months.
He previously spent several years working in rural South America. He has a history of regular alcohol consumption.
During assessment, a radiograph of his pelvis is performed because of pain following the collapse. There is no fracture, but multiple small, elongated calcific densities are incidentally identified within the pelvic and proximal thigh musculature.
Which diagnosis best explains the combination of neurological symptoms and radiographic abnormalities?
A. Progressive multifocal leukoencephalopathy
B. Cerebral toxoplasmosis
C. Neurocysticercosis
D. Chronic subdural haematoma
E. Sporadic Creutzfeldt–Jakob disease
Correct Answer: C. Neurocysticercosis
Key MRCP clue: New-onset seizure + residence in an endemic region + multiple rice-grain calcifications in skeletal muscle = Neurocysticercosis.
Explanation
1. Why is neurocysticercosis the diagnosis?
The patient has three important diagnostic clues:
- Generalised tonic-clonic seizure: Loss of consciousness, limb jerking, urinary incontinence and postictal confusion.
- Progressive neurological deterioration: Personality changes, memory impairment and declining occupational performance.
- Muscle calcifications: Multiple small, elongated calcifications are characteristic of old cysticercal lesions.
His previous residence is epidemiologically relevant because Taenia solium infection is endemic in parts of Latin America.
Neurological manifestations may appear several years after the initial infection. cdc.govcdc.gov
2. Pathophysiology
Causative organism: Taenia solium \(pork tapeworm\), a cestode.
The mechanism is:
- Humans accidentally ingest T. solium eggs through contaminated food or water \(faeco\-oral transmission\).
- Eggs hatch in the intestine, releasing oncospheres.
- Oncospheres penetrate the intestinal wall.
- Larvae enter the bloodstream.
- They reach the brain, skeletal muscles, eyes and other tissues.
- Larvae develop into cysticerci.
- When cysticerci degenerate, an inflammatory reaction occurs, potentially causing seizures and cerebral oedema.
- Eventually, dead cysts may become calcified.
Important MRCP distinction:
| Exposure | Result |
|---|---|
| Eating undercooked pork containing cysticerci | Intestinal taeniasis \(adult tapeworm\) |
| Ingesting T. solium eggs | Cysticercosis, potentially involving the brain |
Eating undercooked pork does not directly cause neurocysticercosis. cdc.govcdc.gov
3. Clinical manifestations
| Site | Manifestations |
|---|---|
| Brain | Seizures, headache, focal neurological deficits |
| Cerebral parenchyma | Inflammation and calcified lesions |
| Ventricular system | Obstructive hydrocephalus |
| Skeletal muscles | Small, elongated rice-grain calcifications |
| Eye | Visual disturbance and intraocular cysts |
| Widespread cerebral involvement | Cognitive and behavioural abnormalities |
4. Investigations
- Non-contrast CT brain: Particularly useful for detecting calcified cysts.
- MRI brain: Better for identifying viable cysts, scolex, surrounding inflammation and ventricular involvement.
- Serology: Enzyme-linked immunoelectrotransfer blot \(EITB\) can support the diagnosis.
- Fundoscopy: Exclude intraocular cysticercosis before antiparasitic treatment.
Brain imaging is essential in a patient presenting with suspected neurocysticercosis and seizures. idsociety.org
5. Treatment
Management depends on the location, number and viability of the cysts.
| Clinical situation | Management |
|---|---|
| Seizures | Antiseizure medication |
| One or two viable parenchymal cysts | Albendazole |
| More than two viable parenchymal cysts | Albendazole + praziquantel |
| Antiparasitic treatment planned | Corticosteroids started beforehand |
| Exclusively calcified brain lesions | Symptomatic treatment; antiparasitic therapy is not indicated |
| Obstructive hydrocephalus | Neurosurgical assessment/intervention |
Exam pearl: Albendazole is generally the preferred antiparasitic agent for viable parenchymal neurocysticercosis, but dead, completely calcified cysts do not benefit from antiparasitic treatment. idsociety.org
Summary for Quick Exam Revision
Neurocysticercosis is a parasitic infection of the central nervous system caused by the larval form of Taenia solium, a cestode or pork tapeworm. It is an important preventable cause of acquired epilepsy, particularly in endemic regions. Infection develops following faeco-oral ingestion of tapeworm eggs rather than directly from eating undercooked pork. Eating undercooked infected pork causes intestinal taeniasis, whereas ingesting eggs causes cysticercosis. After ingestion, oncospheres penetrate the intestinal wall and disseminate through the bloodstream to the brain, skeletal muscles and eyes. The larvae develop into cysticerci, which may remain asymptomatic for many years. When cysticerci degenerate, they produce inflammation, cerebral oedema and seizures. Patients commonly present with new-onset seizures, headaches, focal neurological deficits or cognitive deterioration. Intraventricular cysts may produce obstructive hydrocephalus. Characteristic elongated rice-grain calcifications within skeletal muscle on plain radiographs provide an important diagnostic clue. Non-contrast CT brain is particularly useful for identifying calcified lesions, whereas MRI better demonstrates viable cysts, the scolex and surrounding inflammation. Serological testing using EITB can support the diagnosis. Antiseizure medication should be given to patients presenting with seizures. Viable parenchymal cysts are generally treated with albendazole, with praziquantel added when more than two viable cysts are present. Corticosteroids should be initiated before antiparasitic treatment to reduce treatment-associated inflammation. Completely calcified brain lesions contain no viable parasites and therefore do not require antiparasitic therapy. Remember the classic MRCP association: New-onset epilepsy + previous residence in Latin America + rice-grain skeletal muscle calcifications = Neurocysticercosis.