- Email: [email protected]
Demyelinating Diseases
Demyelinating Diseases
TERMINOLOGY • Acquired demyelinating processes, often autoimmune & characterized by inflammation: Multiple sclerosis (MS), acute disseminated encephalomyelitis (ADEM), Lyme disease, neuromyelitis optica (NMO) (a.k.a. Devic disease)
IMAGING • Best tool: MR brain without & with contrast; ± orbits • MS: Multiple lesions, typically discrete; rarely mass-like ○ Callosal involvement, hemispheric white matter ○ Perpendicular to ventricle margin; often perivenular • ADEM: Frequent brainstem & thalamic involvement • Lyme disease: ± cranial nerve inflammation • NMO: Optic neuritis with spinal cord lesions
PATHOLOGY • MS: Possibly viral-incited autoimmune reaction in genetically susceptible individuals • ADEM: Subsequent to infection or vaccination
• Lyme disease: Caused by spirochete Borrelia burgdorferi • NMO: Associated with serum aquaporin-4 immunoglobulin G antibodies; 20-30% of cases are seronegative
Brain
KEY FACTS
CLINICAL ISSUES • 3-5% of MS diagnosed before age 15 ○ ADEM more frequently diagnosed in children ○ 20% of childhood MS initially diagnosed as ADEM • MS: Initially impaired/double vision of acute optic neuritis, weakness, numbness, tingling, gait disturbances leading to ↓ sphincter control, blindness, paralysis, dementia ○ MS: 45% of patients not severely affected • ADEM: Cranial nerve palsies, encephalopathy, headache 2 days to 4 weeks after prodrome; seizures in 10-35%; classically monophasic • Lyme disease: Stereotypical expanding rash around tick bite (erythema chronicum migrans) • NMO: Rapid vision loss; subsequent spinal cord symptoms
(Left) Axial FLAIR MR in a 9year-old patient with altered mental status & hyperreflexia shows ill-defined hyperintense lesions in the thalami st, basal ganglia ſt, & insula . Involvement of the deep nuclei is a relatively common feature of acute disseminated encephalomyelitis. (Right) Coronal FLAIR MR in a 12year-old patient with neuromyelitis optica & bladder dysfunction shows large lesions extending across the corpus callosum & left cerebral peduncle ſt.
(Left) Axial NECT in a 14-yearold patient with vomiting shows a nonspecific lowattenuation lesion in the left posterior frontal subcortical white matter. (Right) Axial FLAIR MR of the same patient acquired the next day shows several ovoid multiple sclerosis plaques ſt. Active lesions will also demonstrate contrast enhancement & restricted diffusion (not shown here).
325
TERMINOLOGY • Acquired demyelinating processes, often autoimmune & characterized by inflammation: Multiple sclerosis (MS), acute disseminated encephalomyelitis (ADEM), Lyme disease, neuromyelitis optica (NMO) (a.k.a. Devic disease)
IMAGING • Best tool: MR brain without & with contrast; ± orbits • MS: Multiple lesions, typically discrete; rarely mass-like ○ Callosal involvement, hemispheric white matter ○ Perpendicular to ventricle margin; often perivenular • ADEM: Frequent brainstem & thalamic involvement • Lyme disease: ± cranial nerve inflammation • NMO: Optic neuritis with spinal cord lesions
PATHOLOGY • MS: Possibly viral-incited autoimmune reaction in genetically susceptible individuals • ADEM: Subsequent to infection or vaccination
• Lyme disease: Caused by spirochete Borrelia burgdorferi • NMO: Associated with serum aquaporin-4 immunoglobulin G antibodies; 20-30% of cases are seronegative
Brain
KEY FACTS
CLINICAL ISSUES • 3-5% of MS diagnosed before age 15 ○ ADEM more frequently diagnosed in children ○ 20% of childhood MS initially diagnosed as ADEM • MS: Initially impaired/double vision of acute optic neuritis, weakness, numbness, tingling, gait disturbances leading to ↓ sphincter control, blindness, paralysis, dementia ○ MS: 45% of patients not severely affected • ADEM: Cranial nerve palsies, encephalopathy, headache 2 days to 4 weeks after prodrome; seizures in 10-35%; classically monophasic • Lyme disease: Stereotypical expanding rash around tick bite (erythema chronicum migrans) • NMO: Rapid vision loss; subsequent spinal cord symptoms
(Left) Axial FLAIR MR in a 9year-old patient with altered mental status & hyperreflexia shows ill-defined hyperintense lesions in the thalami st, basal ganglia ſt, & insula . Involvement of the deep nuclei is a relatively common feature of acute disseminated encephalomyelitis. (Right) Coronal FLAIR MR in a 12year-old patient with neuromyelitis optica & bladder dysfunction shows large lesions extending across the corpus callosum & left cerebral peduncle ſt.
(Left) Axial NECT in a 14-yearold patient with vomiting shows a nonspecific lowattenuation lesion in the left posterior frontal subcortical white matter. (Right) Axial FLAIR MR of the same patient acquired the next day shows several ovoid multiple sclerosis plaques ſt. Active lesions will also demonstrate contrast enhancement & restricted diffusion (not shown here).
325