Behçet's disease classification

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Hamid Qazi, MD, BSc [2]

Neurologic disease of Behcet disease is classified into parenchymal or non-parenchymal. Parenchymal disease is due to lesions in the corticospinal tract, brainstem, periventricular white matter, spinal cord, and basal ganglia. Focal parenchymal lesions and complications of vascular thrombosis are the most common abnormalities. Progressive personality change, psychiatric disorders, and dementia may develop. Parenchymal disease may be divided into acute and chronic progressive neuro-Behçet syndrome. Central nervous system lesions are detectable with MRI. In the chronic phase, lesions may be smaller or resolve, atrophy may be present, nonspecific white matter lesions may be present, and lesions usually do not enhance. Cerebrospinal fluid (CSF) may show increased protein and increased cells, and neutrophils may predominate. Non-parenchymal disease of Behcet disease include cerebral venous thrombosis, intracranial hypertension syndrome (pseudotumor cerebri), acute meningeal syndrome, and uncommonly stroke due to arterial thrombosis, dissection, or aneurysm. On average, a period of approximately five to six years elapsed between the onset of the earliest non-neurologic symptoms of Behçet syndrome and the appearance of neurologic symptoms or findings.

• Neurologic disease of Behcet disease is classified into parenchymal or non-parenchymal.

• Parenchymal disease is due to lesions in the corticospinal tract, brainstem, periventricular white matter, spinal cord, and basal ganglia.
  • Brainstem disease (which may extend to the midbrain, basal ganglia, and diencephalon) including focal lesions or atrophy with signs and symptoms including ophthalmoparesis, cranial neuropathy, and cerebellar or pyramidal dysfunction are more characteristic of Behçet syndrome than multiple sclerosis.
  • Cerebral lesions are often multiple though may be single, are often subcortical, and are not particularly peri-ventricular, as in multiple sclerosis.
  • Spinal cord lesions (myelitis) may occur in isolation, but are more common in patients with other central nervous system lesions.
  • The clinical presentation of parenchymal disease is often subacute and manifestations may include headache, behavior changes, and deficits reflecting areas of parenchymal involvement.

• Focal parenchymal lesions and complications of vascular thrombosis are the most common abnormalities.
• Progressive personality change, psychiatric disorders, and dementia may develop.
• Unlike many other systemic vasculitic disorders, peripheral neuropathy is uncommon in Behçet syndrome.^[1][2][3]
• Parenchymal disease may be divided into acute and chronic progressive neuro-Behçet syndrome.
  • A meta-analysis reviewed 184 acute and 114 chronic progressive cases, and fever and higher cerebrospinal fluid cell counts were found more commonly in acute disease, and sphincter disturbances, ataxia, confusion, brain stem atrophy on magnetic resonance imaging (MRI), and cerebral changes on MRI were more common in chronic progressive disease.^[4]

• Central nervous system lesions are detectable with MRI.^[5][6]
• Acute and subacute lesions are hypointense or isointense on T1-weighted images; hyperintense on T2-weighted, FLAIR, and diffusion-weighted images; and commonly enhance with contrast.
• In the chronic phase, lesions may be smaller or resolve, atrophy may be present, nonspecific white matter lesions may be present, and lesions usually do not enhance.
• Cerebrospinal fluid (CSF) may show increased protein and increased cells, and neutrophils may predominate.^[7]
• Pathology reveals local perivenular lymphocytic cuffing, inflammatory cell infiltration, gliosis, necrosis, and neuronal loss. Although frank vasculitis is not always observed in parenchymal lesions, it is sometimes noted in larger cerebral vessels, including arteries or veins. Arteritis may lead to ischemic strokes, dissection, aneurysmal dilatation, and subarachnoid hemorrhage.

Non-parenchymal disease of Behcet disease include the following:

• Cerebral venous thrombosis, intracranial hypertension syndrome (pseudotumor cerebri), acute meningeal syndrome, and uncommonly stroke due to arterial thrombosis, dissection, or aneurysm.^[7]

• Central nervous system manifestations may result from arterial or venous thrombosis, including dural sinus thrombosis.^[8]
• Cerebral venous thrombosis may present with headache, papilledema, sixth nerve palsy, and an elevated CSF pressure.^[8][9][10]
• An association has been observed between dural sinus thrombosis and peripheral deep venous thrombosis.^[5]
• Thrombosis of the cerebral arteries may also be observed.^[5][8]
• One analysis of neurologic Behçet syndrome from Turkey, involving 26 children and 702 adults, found that dural venous sinus thrombosis was much more common in children than parenchymal neurologic involvement, although parenchymal disease was more frequent in adults.^[11]

• In one large series, the clinical features and outcomes of 200 patients with Behçet syndrome and neurologic involvement were reported.^[5]
• On an average, a period of approximately five to six years elapsed between the onset of the earliest non-neurologic symptoms of Behçet syndrome and the appearance of neurologic symptoms or findings.
• Nevertheless, neurologic findings may also appear concurrently (7.5 percent) or precede non-neurologic features (3 percent). Twenty percent of those with neurologic findings were asymptomatic.

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