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# Other demyelinating diseases

- Lesion

Several diseases besides multiple sclerosis destroy myelin: antibody attacks on astrocytes, immune reactions after infection, and rapid sodium shifts.

Updated Nov 12, 2026

## Key points

- NMO: anti-aquaporin-4 IgG; astrocyte loss, complement deposition, neutrophils and eosinophils; optic neuritis and longitudinally extensive myelitis over three or more segments.
- NMO is an astrocytopathy, so GFAP is lost; it responds poorly to some MS drugs.
- MOG antibody disease: optic neuritis, myelitis or ADEM-like illness, often in children.
- ADEM: perivenous demyelination of the same age everywhere, one to two weeks after infection; monophasic.
- Acute hemorrhagic leukoencephalitis: necrotising vasculitis of venules with hemorrhage and fibrin; rapid course.
- Osmotic demyelination: symmetric loss of myelin in the basal pons (and other sites) after rapid correction of hyponatremia, often in alcoholism or malnutrition.

## What it is

Demyelinating diseases other than MS differ in their target and timing. Neuromyelitis optica is an antibody disease against aquaporin-4 on astrocyte end-feet, with severe optic neuritis and long cord lesions. MOG antibody disease targets oligodendrocyte surface protein. Acute disseminated encephalomyelitis is a monophasic immune attack after infection or vaccination, and its hyperacute hemorrhagic form is often fatal. Osmotic demyelination (central pontine myelinolysis) follows too-rapid correction of low sodium.

## Structure

- NMO lesions are often necrotic, with thickened hyalinised vessels and loss of aquaporin-4 and GFAP staining.
- Osmotic demyelination: myelin loss with oligodendrocyte death but relatively preserved axons and neurons, without inflammation.

## Demyelinating diseases compared

| Disease | Target or trigger | Lesions | Course |
| --- | --- | --- | --- |
| [Multiple sclerosis](https://durgical.com/en/conditions/multiple-sclerosis/) | Myelin, T and B cells | Plaques of different ages | Relapsing, then progressive |
| [Neuromyelitis optica](https://durgical.com/en/conditions/neuromyelitis-optica-spectrum-disorder/) | Aquaporin-4 on astrocytes | Optic nerves, long cord segments, area postrema | Relapsing, severe attacks |
| MOG antibody disease | Myelin oligodendrocyte glycoprotein | Optic nerve, cord, brain | Monophasic or relapsing |
| ADEM | Recent infection or vaccination | Perivenous demyelination, all the same age | Monophasic |
| Acute hemorrhagic leukoencephalitis | Post-infectious, hyperacute | Hemorrhagic necrosis of venules | Often fatal within days |
| [Osmotic demyelination](https://durgical.com/en/conditions/osmotic-demyelination-syndrome/) | Rapid rise in sodium | Central pons, symmetric | Quadriparesis, locked-in state |

## Clinical notes

- Bilateral or severe optic neuritis, or a long spinal cord lesion, should prompt testing for aquaporin-4 and MOG antibodies.
- Sodium is corrected slowly in chronic hyponatremia to prevent osmotic demyelination.

## Memory aid

NMO hits the water channel (aquaporin) in astrocytes; ADEM is one storm after an infection; the pons dissolves when sodium rises too fast.

## Test yourself

Think of the answer, then tap the question to see it.

## What is the target antigen in neuromyelitis optica?

Aquaporin-4, a water channel on astrocyte end-feet; the disease is an astrocytopathy.

## How does ADEM differ from MS in timing?

ADEM is usually monophasic, after infection or vaccination, with lesions all of the same age; MS relapses with lesions of different ages.

## What causes central pontine myelinolysis?

Overly rapid correction of chronic hyponatremia, which injures oligodendrocytes osmotically.

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## Elsewhere in DurgiPedia

- [Autoantibodies: the table to know](https://durgical.com/en/immunology/autoantibodies-the-table-to-know/)
- [Type II hypersensitivity (antibody against cells)](https://durgical.com/en/immunology/type-ii-hypersensitivity/)

## Connections

## Related 4

- [Multiple sclerosis: the plaque](https://durgical.com/en/general-pathology/multiple-sclerosis-the-plaque/)
- [Viral encephalitis: the shared pattern](https://durgical.com/en/general-pathology/viral-encephalitis-the-shared-pattern/)
- [HIV in the brain and PML](https://durgical.com/en/general-pathology/hiv-in-the-brain-and-pml/)
- [Optic neuropathies](https://durgical.com/en/general-pathology/optic-neuropathies/)

## Related conditions 7

- [Neuromyelitis optica spectrum disorder](https://durgical.com/en/conditions/neuromyelitis-optica-spectrum-disorder/)
- [Transverse myelitis](https://durgical.com/en/conditions/transverse-myelitis/)
- [Optic neuritis](https://durgical.com/en/conditions/optic-neuritis/)
- [Osmotic demyelination syndrome (central pontine myelinolysis)](https://durgical.com/en/conditions/osmotic-demyelination-syndrome/)
- [Hyponatraemia](https://durgical.com/en/conditions/hyponatraemia/)
- [Alcohol use disorder](https://durgical.com/en/conditions/alcohol-use-disorder/)
- [Multiple sclerosis](https://durgical.com/en/conditions/multiple-sclerosis/)

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Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.

Sources: [Neuromyelitis optica: MedlinePlus Genetics](https://medlineplus.gov/genetics/condition/neuromyelitis-optica/) (MedlinePlus, US National Library of Medicine, 2026).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/general-pathology/other-demyelinating-diseases/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/general-pathology/other-demyelinating-diseases/