Tuesday, February 23, 2016

Cognition and neuropsychiatry in behavioral variant FTD by disease stage

Ranasinghe KG, Rankin KP, Loach IV et al. Neurology, 2016; 86: 600-610.
authors examined a cohort of 204 patients with clinical dementia rating. 
Early stages of the disease were characterized by profound neuropsychiatric symptoms, insensitivity to errors, slower response times and poor naming.
Stepwise declines that occurred in later stages included free recall, visuoconstruction, set shifting, error insensitivity, semantic and design fluency, emotion naming, calculations, syntax comprehension and verbal agility. 
Error insensitivity is called a highly sensitive index of early bv FTD and is likely attributed to the right lateral prefrontal cortex which is responsible for response inhibition and sensitivity to rule violations (esp IFG). Early patients show impaired processing speed and fluency tasks, but are adequate on attention and working memory, and visuoperceptual processing.
bvFTD patients get "denkfaulheit" or an early amotivational syndrome sometimes called emotional laziness.   They may score poorly due to noncooperation and disruption of the "ventral salience network stuctures" to identify pedrsonally salient stimuli. 

Vascular risk factors in suspected NPH

Jaraj D, Agerskov A, Rabiei K et al. Vascular risk factors in suspected normal pressure hydrocephalus. A population based study.  Neurology 2016; 86: 592-599 
Authors found that hypertension, white matter lesions on MRI and diabetes were related to clinical and imaging features of NPH suggesting vascuar mechanisms;
and  editorial 
Graff-Radford NR. Is normal pressure hydrocephalus becoming less idiopathic?  Neurology 2016; 86: 588-89.
Dr. Graff Radford discusses that the problem usually cited, resistance to CSF outflow, is problematic as an etiology as some patients with normal CSF outflow resistance  also present with hydrocephalus.  He points out that more than 10 %of patients with iNPH have congenital hydrocephalus, and more than 10 % have a head size above the 98th percentile. 
Ventricular pulse pressure is related to iNPH, and ligating the choroid plexus in dogs unilaterally (prventing pulse pressure) prevents hydrocephalus in that but not the other ventricle. 
In a human study, patients with iNPH but without an absorption problem underwent shunting; these patients had severe vascular risk factors.  They improved with shunting.  The small study (n=14) was blinded and randomized sothe control group had their shunts ligated for three months in the neck and only improved after un-ligation. 
He regards the question of vascular risk factors as etiologic to be unresolved.