Current concepts on the pathophysiology of idiopathic chronic adult hydrocephalus: Are we facing another neurodegenerative disease?
BACKGROUND
Since its description five decades ago, the pathophysiology of idiopathic chronic adult hydrocephalus (iCAH) has been traditionally related to the effect that ventricular dilatation exerts on the structures surrounding the ventricular system. However, altered cerebral blood flow, especially a reduction in the CSF turnover rate, are starting to be considered the main pathophysiological elements of this disease.


METHODS
Compression of the pyramidal tract, the frontostriatal and frontoreticular circuits, and the paraventricular fibres of the superior longitudinal fasciculus have all been reported in iCAH. At the level of the corpus callosum, gliosis replaces a number of commissural tracts. Cerebral blood flow is also altered, showing a periventricular watershed region limited by the subependymal arteries and the perforating branches of the major arteries of the anterior cerebral circulation. The CSF turnover rate is decreased by 75%, leading to the reduced clearance of neurotoxins and the interruption of neuroendocrine and paracrine signalling in the CSF.


CONCLUSIONS
iCAH presents as a complex nosological entity, in which the effects of subcortical microangiopathy and reduced CSF turnover play a key role. According to its pathophysiology, it is simpler to think of iCAH more as a neurodegenerative disease, such as Alzheimer disease or Binswanger disease than as the classical concept of hydrocephalus.
Servicio de Neurocirugía, Hospital Universitario «Marqués de Valdecilla», Santander, Cantabria, España. Electronic address: rmlaez@yahoo.es.
R
R
Martín-Láez
Servicio de Radiología, Hospital Universitario «Marqués de Valdecilla», Santander, Cantabria, España.
N
N
Valle-San Román
Servicio de Neurología, Hospital Universitario «Marqués de Valdecilla», Instituto de Investigación Sanitaria IDIVAL, Centro de Investigación Biomédica en Red en Enfermedades Neurodegenerativas (CIBERNED), Universidad de Cantabria, Santander, Cantabria, España.
E M
EM
Rodríguez-Rodríguez
Servicio de Radiología, Hospital Universitario «Marqués de Valdecilla», Santander, Cantabria, España.
E
E
Marco-de Lucas
Servicio de Neurología, Hospital Universitario «Marqués de Valdecilla», Instituto de Investigación Sanitaria IDIVAL, Centro de Investigación Biomédica en Red en Enfermedades Neurodegenerativas (CIBERNED), Universidad de Cantabria, Santander, Cantabria, España.
J A
JA
Berciano Blanco
Servicio de Neurocirugía, Hospital Universitario «Marqués de Valdecilla», Santander, Cantabria, España.
A
A
Vázquez-Barquero
D000328:Adult; D002552:Cerebral Ventricles / Q000503:physiopathology; D015170:Cerebrospinal Fluid Pressure / Q000502:physiology; D002560:Cerebrovascular Circulation / Q000502:physiology; D002908:Chronic Disease; D006801:Humans; D006850:Hydrocephalus, Normal Pressure / Q000134:cerebrospinal fluid / Q000175:diagnosis / Q000503:physiopathology*; D019636:Neurodegenerative Diseases / Q000134:cerebrospinal fluid / Q000175:diagnosis / Q000503:physiopathology*
Aclaramiento licuoral; Cerebral blood flow; Cerebrospinal fluid clearance; Cerebrospinal fluid turnover; Diffusion tractography; Fisiopatología; Flujo sanguíneo cerebral; Hidrocefalia crónica del adulto idiopática; Idiopathic chronic adult hydrocephalus; Pathophysiology; Recambio licuoral; Tractografía por tensor de difusión