Clinical Presentations of Neurocysticercosis (NCC)

Gross Pathology — Brain Cysticercosis

Multiple cysticercal cysts at the gray-white junction (Sherris & Ryan's Medical Microbiology)

I. CNS Involvement

A. Parenchymal Neurocysticercosis

1. Single Enhancing Lesion (SEL)

• Most common manifestation in India and the United States
• Patient presents with headache or seizures (focal or focal with secondary generalization)
• Many have a single seizure or a few seizures during the period when the cysticercus is degenerating; seizures are eventually self-limited in most
• Some cases progress to calcified lesions, which are a risk factor for recurrent seizures

2. Multiple Parenchymal Cysticerci

• Main presentation is seizures associated with parenchymal inflammation
• Seizures are more likely to recur than with single lesions

3. Calcified Lesions

• Patients may develop recurrent seizures over years
• Some develop mesiotemporal sclerosis leading to refractory epilepsy
• Calcified lesions can intermittently become inflamed (edema/contrast enhancement on MRI) and trigger additional seizure episodes

4. Cysticercal Encephalitis

• Occurs with massive larval invasion, producing diffuse cerebral edema
• Presents as encephalopathy, raised ICP, seizures
• More common in children and young women
• Antiparasitic drugs are contraindicated in this form; treat with steroids only

B. Ventricular Cysticercosis

• Cysticerci most commonly lodge in the 4th ventricle, followed by 3rd and lateral ventricles
• Causes obstructive hydrocephalus — a medical emergency
• Symptoms: headache, nausea, vomiting, dizziness, altered mental status, papilledema with altered visual acuity
• A cysticercus in the 4th ventricle acting as a ball valve causes Bruns syndrome: intermittent acute hydrocephalus triggered by changes in head position — sudden severe headache, vomiting, loss of consciousness, and sometimes sudden death

C. Subarachnoid/Cisternal (Racemose) Cysticercosis

• Cysticerci in the basilar cisterns are often multilobulated ("racemose" = cluster-of-grapes form), can grow to several centimeters
• Typically accompanied by cysticerci at other locations (parenchymal, ventricular, spinal, or ocular)
• The cysts induce chronic arachnoiditis, with:
  • Communicating hydrocephalus (headache, nausea, vomiting, dizziness, altered mental status)
  • Chronic meningitis / meningeal signs
  • Vascular involvement: large- or small-vessel strokes (arteritis)
  • Mass effect
  • Hemorrhage
• This is the most severe form of NCC with the highest fatality rate

D. Spinal Cysticercosis

• Less common
• Produces cord compression or meningeal inflammation (radiculitis)
• Symptoms: back/radicular pain, limb weakness, sensory deficits, myelopathy
• May present as chronic progressive paraparesis

Neuroimaging Overview

Goldman-Cecil Medicine: NCC classification by neuroimaging — note panel G (ocular) and H (muscle calcifications)

"Hole-with-dot" sign on MRI: cystic lesion + scolex nodule = pathognomonic of vesicular-stage NCC

II. Ocular Cysticercosis

• Occurs in ~1–3% of all NCC cases; the eye may be the only site of involvement
• Cysts may lodge in:
  • Vitreous humor (most common intraocular location)
  • Subretinal space
  • Anterior chamber
  • Extraocular muscles (less common)
• Symptoms:
  • Ocular pain and visual disturbances (floaters, blurring, decreased acuity)
  • If subretinal: retinal detachment risk
  • The degenerating cyst provokes severe inflammatory reaction with endophthalmitis → blindness
• Absolute diagnostic criterion: direct visualization of subretinal parasites by fundoscopic examination (shows the scolex)
• Note: Antiparasitic drugs are contraindicated in ocular cysticercosis — destruction of the cyst in the eye causes severe intraocular inflammation; surgical removal is the treatment of choice

III. Muscular Cysticercosis

• Generally asymptomatic as long as cysts remain viable (the live cyst suppresses host inflammatory response)
• Death of larvae → marked inflammatory reaction: fever, muscle pain, swelling, tenderness, and eosinophilia
• Heavy infection: pseudohypertrophy of muscles (especially tongue — classical)
• Cysts calcify over time → appear as characteristic cigar-shaped (rice-grain) calcifications on plain X-ray, most prominent in the limbs and trunk
• These calcifications are a minor criterion in NCC diagnostic scoring (evidence of cysticercosis outside the CNS)
• Headache can accompany all forms of disease

IV. Subcutaneous Cysticercosis

• Presents as firm, mobile, non-tender subcutaneous papulonodules, usually multiple
• More often palpable than visible
• Typically asymptomatic
• When the cyst dies: local inflammation, tenderness, eventually calcification
• Prevalence varies by region: recognized in <1%–20% of patients; more common in Asia and Africa than Latin America
• In some series (Brazil): 90% of patients had cysts in subcutaneous tissue, skeletal muscle, or mucous membranes, while CNS was affected in <10%
• On plain radiograph: calcified cysts visible in soft tissues
• Clinical importance: the presence of subcutaneous cysticercosis should always prompt evaluation for NCC — surgical biopsy of a subcutaneous nodule can confirm the diagnosis (demonstrating the larva), and the finding counts as a major clinical/exposure criterion for NCC diagnosis

Summary Table