Neither the diagnostic criteria nor the pathogenesis of the normal pressure hydrocephalus (NPH) syndrome has been fully clarified. In two cases fulfilling currently accepted clinical and radiologic criteria, autopsy showed extensive hypertensive cerebrovascular disease with multiple small infarcts of the deep cerebral and cerebellar gray and white matter but normal leptomeninges and arachnoid villi. Therefore, hypertensive vascular disease with multiple deep cerebral infarctions may be the initial pathologic process in some cases of NPH. Such infarctions could reduce periventricular tissue tensile strength and elastic properties permitting the ventricles to enlarge under the stress of the intraventricular pulse pressure. Some patients with so-called arteriosclerotic parkinsonism and arteriosclerotic dementia clinically resemble patients with NPH. Some of these cases could represent NPH due to multiple small infarctions and, as in one of the cases reported here, might improve following ventricular shunting. (Arch Neurol 31:262-266, 1974) The syndrome of normal pressure hydrocephalus (NPH)1·2 includes the clinical triad of dementia, abnor¬ mal gait, and urinary incontinence, associated with hydrocephalus and normal lumbar cerebrospinal fluid (CSF) pressure. Diagnostic criteria have not yet been defined finally, but currently include a pneumoencephalo¬ gram demonstrating communicating hydrocephalus with little or no air over the convexities, and an iodinated serum albumin (RISA) or equivalent isotope cisternogram indicating absent or delayed CSF flow over the convexities, often with reflux into the ventricular system.38The syndrome may follow chronic meningitis,810 subarachnoid hemor¬ rhage,1113 or head trauma,1·14 and has been associated with ectasia of the basilar artery,15·16 ventricular tu¬ mors,2·6·10·17 aqueductal stenosis,17 and even Alzheimer disease.8 However, in most series there are patients with no overt precipitating event or anatomi¬ cal cause.1018 Few postmortem exami¬ nations of the "idiopathic" cases have been reported: Four showed thick¬ ened, adherent pia-arachnoid at the base, especially at the incisura or over the convexities,5·19·20 and two showed Alzheimer disease.8·21The mechanisms causing ventricu¬ lar enlargement with no increase in CSF pressure are unclear. The basic problem seems to be a block of normal CSF flow, but the relative importance of total force on the ventricular walls, tensile strength, and elasticity of periventricular tissues or altered CSF and arterial pulse pressures iti! uncer¬ tain.12·22·23 Nonetheless, the recom¬ mended therapy is a shunt drain¬ age of the ventricular system with striking improvement in some pa¬ tients.2·5·7·10·18We now report two autopsied cases that demonstrate a previously unreported association of the NPH syn¬ drome and hypertensive cerebrovascu¬ lar disease with multiple small cere¬ bral infarctions.
Report of CasesCase l.-At age 64, this university pro¬ fessor developed an unsteady shuffling gait, failing memory, and increasing diffi¬ culty con...
