Our colleague S.M. Greenberg (1993) and others have emphasized certain clinical features associated with an inflammatory type of cerebrovascular amyloidosis (see Kinnecom et al and Eng et al), which is referred to as cerebral amyloid angiopathy-related inflammation. Included in the clinical picture are encephalopathy, seizures, headache, and focal cerebral symptoms such as aphasia. The MRI appearance is of large subcortical and cortical patches of abnormal T2 hyperintensity suggestive of cerebral edema. The findings are similar to the mainly white matter encephalitis that was found in some patients with Alzheimer disease who were treated with a monoclonal antibody directed against a-beta amyloid. This disease subtype has a significantly younger age at presentation compared to cerebral amyloid angiopathy and is strongly associated with the APOE ε4/ε4 genotype. It is treated with a course of high-dose corticosteroids or other forms of immunosuppression and some improvement is to be expected though outcomes may be unfavorable.
An apparently separate granulomatous or nongranulomatous angiitis has been reported, mainly as a pathologic entity but its clinical characteristics are similar to the inflammatory type. The relationship of this entity to primary granulomatous angiitis of the central nervous system is unclear.
There is a separate familial amyloidotic condition of diffuse white matter degeneration with dementia, associated in some families with calcification in the occipital lobes, and the aforementioned mutations in the COL4A gene cause a disruption of the small vessel wall that can cause small cerebral hemorrhages that are similar to those of typical cerebrovascular amyloid.
Hypertensive encephalopathy is the term applied to a relatively rapidly evolving syndrome of severe hypertension, usually systolic pressure above 195 mm Hg, in association with headache, nausea and vomiting, visual disturbances, confusion, and—in advanced cases—stupor and coma. Multiple seizures may occur and may be more marked on one side of the body. In special circumstances, the absolute level of blood pressure seems less pertinent that is a rapid rise in pressure as occurs in eclampsia and with exposure to certain drugs. The neurologic syndrome is usually dominated by symptoms referable to the occipital and adjacent parietal region. There may be visual field deficits, hallucinations, Balint syndrome, and cortical blindness. An indistinguishable syndrome with similar imaging characteristics also occurs with the use of a variety of mainly cancer chemotherapeutic agents as discussed in Chap. 41 and Table 41-1. Papilledema and retinal hemorrhages are frequent accompaniments and it was stated at one time that the diagnosis should not be made without those findings.
Diffuse cerebral disturbance may be accompanied by focal or lateralizing neurologic signs, either transitory or lasting, which may suggest cerebral hemorrhage or infarction, that is, the more common cerebrovascular complications of severe chronic hypertension. A clustering of multiple microinfarcts and petechial hemorrhages (the basic neuropathologic changes in hypertensive encephalopathy) in one region may occasionally result in a mild hemiparesis, aphasic disorder, or rapid failure or the above-noted distortion of vision.