The administration of prednisone, 50 to 75 mg/d, provides striking relief of the headache and polymyalgic symptoms within days and sometimes within hours, and also prevents blindness. The medication must be given in gradually diminishing doses for at least several months or longer, guided by the symptoms and the sedimentation rate. The latter begins to drop within days but seldom falls below 25 mm/h. These issues are discussed in greater detail in Chap. 9.
Scattered examples of smalland medium-sized vessel giant cell arteritis of undetermined etiology in which only brain vessels are affected have come to medical attention over the years. The clinical aspects have taken diverse forms, sometimes presenting as low-grade, nonfebrile meningitis with sterile CSF followed by infarction of one or several parts of the cerebrum or cerebellum. In other cases, it has evolved over a period of weeks, with strokes or an unusual dementia. Headaches (variable in our experience but sometimes severe), focal cerebral or cerebellar signs of gradual (occasionally stroke-like) evolution, confusion with memory loss, pleocytosis and elevated CSF protein, and papilledema as a result of increased intracranial pressure (in about half of reported cases but far fewer in our experience) constitute the most frequently encountered syndromes. The symptoms usually persist for several months. In contrast to temporal arteritis, the sedimentation rate is generally normal or only slightly elevated. An extensive early report given by Kolodny and colleagues still serves as a useful reference.
In about half the patients can the diagnosis be made by angiography, which demonstrates an irregular narrowing and in some cases blunt ending of several medium-sized cerebral arteries (Fig. 33-37). CT and MRI show multiple irregular white matter and cortical changes and small cortical lesions; sometimes these cannot be differentiated from a tumor or demyelinative or infectious process. If the white matter abnormalities become confluent, the radiologic appearance simulates Binswanger disease. The diagnosis is inferred from the imaging and CSF examination but made often by a brain biopsy, which includes a sample of the meninges with vessels, but even with tissue sampling, about half of suspected cases show the typical histopathologic changes. It is not unusual, however, for patients with normal angiograms to have the typical arteritic findings on biopsy. Tissue excised during an operation (or brain biopsy) for a suspected brain tumor, lymphoma, or white matter disease has revealed the characteristic vasculitis in some of our patients; in others, the diagnosis has been made only at autopsy, the findings coming as a distinct surprise.
The affected vessels are mainly in the 100to 500-mm-diameter arteries and arterioles and are surrounded and infiltrated by lymphocytes, plasma cells, and other mononuclear cells; giant cells are distributed in small numbers in the media, adventitia, or perivascular connective tissue. Infarction of brain tissue can be traced to widespread thrombosis in these vessels. The meninges are variably infiltrated with inflammatory cells. Sometimes only a part of the brain has been clinically affected—in one of our cases the cerebellum, in another, one frontal lobe and the opposite parietal lobe.