Infections

Question 1

A 34 year-old man from Mexico presented with a long history of seizures.

Answer 1

Neurocysticercosis

Background

• Infection with Taenia solium = pork tapeworm
• Most common parasitic infection in CNS
• Commin in India, Mexico, South America, Asia, Africa

Clinical features

• Mass effect and edema = focal neuro deficits, headache
• Seizures

Imaging

• Ring-enhancing
• “Dot in a hole” sign

Treatment

• Albendazole
• Glucocorticoids

Question 2

HIV patient with left-sided weakness.

Answer 2

Toxoplasmosis

Background

• Toxoplasma gondii parasite
• CD4 < 200

Clinical features

• Fever, decreased mental status, focal neuro deficits, headache, seizure
• Toxoplasma IgG positive

Imaging

• Ring-enhancing
• “Target” sign
• On CT, hypodense
  
  • Primary CNS lymphoma is hyperdense!
• Usually in basal ganglia or gray-white junction

Treatment

• Trimethoprim-sulfamethoxazole (Bactrim)

Question 3

A 54 year-old man with HIV presented with dementia and personality changes.

Answer 3

Progressive multifocal leukoencephalopathy (PML)

Background

• JC virus
• CD4 < 200

Clinical features

• Focal neuro deficit, weakness, sensory deficit, visual problems, aphasia, cognitive decline
• Death within a year

Diagnosis

• JC virus via PCR in CSF

Imaging

• Asymmetric white matter lesion
• Bright on T2WI
• Dark on T1WI

Treatment

• HAART

Question 4

45 year-old HIV patient with confusion and lethargy after starting HAART.

Answer 4

PML with IRIS (immune reconstitution inflammatory syndrome)

• Massive inflammatory response after HIV patient has reconstitution of immune system
• Patients with low CD4 counts not on HAART are at highest risk

Question 5

A 45 year-old man with untreated HIV infection presented with 4 months of cognitive slowing.

Answer 5

HIV dementia

Background

• Late stage of HIV infection
• Low CD4, patients not on HAART

Clinical features

• Personality changes, psychomotor retardation, subcortical dementia
  
  • Attention, executive function, slow processing speed
  • Langauage and memory intact

Imaging

• Symmetric white matter hyperintensities
• Looks like CMV, PML, lymphoma!

Treatment

• HAART

Question 6

An otherwise healthy 23-year-old man presented with confusion and trouble speaking for 3 days. There was no prior trauma.

Answer 6

Herpes encephalitis

Background

• Most common cause of viral encephalitis (HSV-1)

Clinical features

• Rapid encephalitis, seizure, headache, changes in cognition and personality
• Fever
• CSF is bloody, high WBC, HSV PCR positive

Imaging

• Asymmetric
• Hemorrhagic necrosis of inferior frontal and temporal lobes

Treatment

• IV acyclovir

Question 7

A 56 year-old immunocompromised man presented with seizures.

Answer 7

Aspergillosis

Background

• Aspergillus fungus
• Necrotizing vasculitis - hemorrhagic abscesses in ependymal region
  
  • Infarction is common

Diagnosis

• Aspergillus PCR

Imaging

• Looks like metastasis, but calcification and ring-enhancing
• Infarctions on DWI

Question 8

A 65 year-old man with dementia.

Answer 8

Creutzfeldt-Jakob Disease (CJD)

Background

• Prion protein leads to toxic gain of function
• Familial, infectious, and iatrogenic forms

Clinical features

• Rapid onset of dementia, personality changes, (3-4 months)
• Myoclonus, ataxia, weakness, sensory deficit
• Fatal within a year
• CSF = 14-3-3 protein

MRI

• “Double hockey stick” sign
• Cortical ribboning
• Abnormal T2WI and DWI of basal ganglia, thalamus

Question 9

A 65 year-old man presented with the rapid-onset rapid progression of dementia and myoclonus.

Answer 9

Creutzfeldt-Jakob Disease (CJD) with cortical ribboning

Question 10

A 54 year-old man presented with headaches and weakness on his left side.

Answer 10

Abscess

Background

• Commonly from infection of middle ear, mastoiditis, or hematogenous spread
  
  • Pulmonary or endocarditis
• Usually multiple organisms
  
  • Strep, Bacteroides, Enterobacter, Staph
  • Biopsy needed to make diagnosis

Clinical features

• Headache, seizure, nausea/vomiting, focal neuro deficits
• Unlike meningitis, no fever or neck pain!

Imaging

• Hard to distinguish from neoplasm
• Restricted diffusion on DWI

Treatment

• Empiric antibiotics - vancomycin, metronidazole, 3rd gen. cephalosporin
• Surgical drainage

Question 11

Encephalopathy and seizures in a patient with endocarditis from intravenous drug abuse.

Answer 11

Cerebral abscesses (early formation)

• In early stage abscesses, there is edema
• In late stage abscesses, there is capsule formation​ (image below)

Question 12

Febrile, lethargic newborn.

Answer 12

Group B streptococcal meningitis

Background

• Most commonly from hematogenous spread from URI to choroid plexus
• Blood culture is diagnostic

Clinical features

• Stiff neck, fever, headache, altered mental status
• Focal neuro deficits (usually hearing loss)
• Seizure
• Lethargy, poor feeding, hypothermia in infants

Diagnosis

• CSF shows:
  
  • High WBC
  • Low glucose
  • High protein
  • High opening pressure

Imaging

• Not important to do imaging unless there is suspicion of mass lesions that precludes LP
• Meningeal enhancement
• Hydrocephalus, subdural empyema, infarction

Treatment

• Empirical antibiotics - 3rd gen. cephalosporin
• Corticosteroids

Question 13

28 year-old developed cranial nerve deficits and soon became encephalopathic and died.

Answer 13

Tuberculosis meningitis

Background

• Hematogenous spread from lungs

Clinical features

• Cranial nerve deficits (CN VI)
• Altered mental status, seizures, hydrocephalus
• CSF
  
  • High protein
  • Low glucose
  • Lymphocytic pleocytosis
  • Acid fast bacilli + PCR positive

Imaging

• Numerous ring-enhancing lesions = tuberculomas