Parasitic CNS Diseases and Hydatidosis — WACS Viva & Clinical Scenarios (Central Nervous System Infections and Infestations)

Exam-style parasitic cns diseases and hydatidosis viva scenarios with examiner probes and model answers for Neurosurgery candidates.

Scenarios covered

• SCENARIO 1: A 9-year-old child from a pastoralist community presents with a 6-month history of progressive headache, papilloedema, and left-sided hemiparesis. Cranial MRI demonstrates a solitary, large (7 cm diameter), spherical, thin-walled, non-enhancing unilocular cystic lesion in the right parieto-occipital region with marked midline shift but no surrounding vasogenic edema. Discuss your operative strategy, detailing the principles and step-by-step execution of the Dowling-Orlando technique, your measures to prevent intraoperative cyst rupture, and your management protocol should rupture occur.
• SCENARIO 2: A 32-year-old male presents with new-onset generalized tonic-clonic seizures. Contrast-enhanced cranial CT shows multiple parenchymal ring-enhancing and calcified lesions, as well as a non-enhancing, cystic lesion with an eccentric hyperdense dot within the fourth ventricle causing non-communicating hydrocephalus. Outline the diagnostic evaluation using formal diagnostic criteria, describe the neuropathological staging of these lesions, and formulate a definitive neurosurgical and medical management algorithm.
• SCENARIO 3: A 38-year-old HIV-seropositive patient (CD4 count 45 cells/microliter) presents with altered mental status, fever, and a right third nerve palsy. Cranial MRI reveals multiple ring-enhancing lesions in the basal ganglia and corticomedullary junction with surrounding edema and moderate mass effect. Detail your diagnostic approach to differentiate toxoplasmosis from primary CNS lymphoma, define the indications and technique for stereotactic brain biopsy, and specify the medical rescue protocols.
• SCENARIO 4: A 24-year-old woman presents with progressive spastic paraparesis, lower extremity sensory loss up to the T10 dermatome, and urinary retention. Spinal MRI demonstrates an expansile, multiloculated extradural cystic lesion causing severe thoracic cord compression and vertebral body erosion. Discuss the differential diagnosis of parasitic spinal cord compression, focusing on spinal echinococcosis and spinal schistosomiasis, their pathological mechanisms, and surgical decompression strategies.
• SCENARIO 5: A 6-year-old boy is admitted in a comatose state (Blantyre Coma Score 2/5) with recurrent generalized convulsions, severe pallor, and fixed pinpoint pupils in an endemic tropical zone. Peripheral blood smear demonstrates Plasmodium falciparum parasitaemia. Discuss the surgical pathophysiology of intracranial hypertension in cerebral malaria, the criteria to rule out emergent surgical neurocranial pathologies, and the neuro-intensive care protocols required to optimize cerebral perfusion pressure.