PRIMARY CENTRAL NERVOUS SYSTEM VASCULITIS
Primary central nervous system vasculitis is characterized by isolated inflammation of the cerebral blood vessels walls carrying oxygenated blood (cerebral arteries) in the absence of any other general, infectious or tumorous disease. Two types of primary vasculitis could be highlighted, with different clinical, radiological and prognostic characteristics: vasculitis affecting large or medium caliber arteries and vasculitis involving the distal or small arteries.
The causes of disease
In the most of the cases, the disease could be isolated and sometimes it can be associated with other systemic diseases (e.g lupus, Behcet disease, Gougerot Sjoegren diseases…)
The vasculitis affecting large or medium caliber arteries will be characterized essentially by a localized neurological deficit, resulting in hemiplegia or hemiparesis, impression of heaviness of the limbs and gait disorders. More than 50% of children complain of headaches while cognitive difficulties are found in 30% of cases.
Symptoms of small vessel vasculitis affect several areas, headaches and general symptoms such as fever or fatigue may be predominant. Localized disorders such as optic neuritis (involvement of the eyes) or myelitis (spinal involvement) have also been described. Biological inflammatory markers are often normal. Pleiocytosis, increase of protein in the CSF and increased CSF pressure are frequently found. MRI lesions are often multifocal and involve the cortico-subcortical regions. Cerebral arteriography is negative, and sometimes, eyes fluorescein angiography can guide the diagnosis by demonstrating the presence of localized vascular lesions. Only the cerebral biopsy can confirm the diagnosis.
Evidence of the disease
In 50% of the cases, inflammatory markers abnormalities (ESR and CRP) can be observed and abnormalities can also be found in the CSF study (39% of cases with pleiocytosis (number of cells) and / or increased protein level in 32% of these children). Usually, cerebral MRI and conventional arteriography may show the presence of vasculitis-like lesions affecting large or medium caliber vessels, resulting in tortuous, stenosed or occluded vessels. Two forms of evolution are possible in these vasculitides: a monophasic or “non-progressive” form, which manifests mainly in unilateral vascular accident involving the anterior proximal vessels and / or the middle cerebral artery. However, in the progressive form, there is a multiple clinical impairment with headaches, cognitive and neuropsychiatric disorders. Angiography also showed multifocal involvement in the proximal and distal segments, with the appearance of new angiographic lesions at 3 months of the disease.
The neurological prognosis of children is always serious. Recent observational studies suggest that 1/3 of children with non-progressive large or medium-sized vessels vasculitis recovered completely after one year and without corticosteroid therapy, recovery would be less complete. Furthermore, 50% of children with small vessel vasculitis had complete recovery after 1 year and 50% had moderate cognitive difficulties and sensory disorders.
In non-progressive vasculitis of large and medium caliber arteries, antiplatelet therapy is often established, and a preliminary study in 58 children suggested that the association of corticosteroids may reduce the risk of recurrence.
Regarding progressive vasculitis and vasculitis of small vessels, cyclophosphamide therapy for 6 months followed by azathioprine or mycophenolate mofetil for 18 months are proposed.
An association with corticosteroids early in the disease with a 12 months gradual dose reduction is often associated with good neurological outcome in vasculitis of small vessels.