[Dysphagia] vocal cord paralysis and dysphagia

[MBenoit at providencehealth.bc.ca (Benoit, Mia [PH])]

Hi,
I'm wondering if anyone has any advice or ideas about this case. 
Pt is a 48 year old man with a history of alcohol and abuse. Came to hospital with a Dx of necrotizing pneumonia. Pt has been in the hospital for ~3 months, has been intubated, extubated, trached and decannulated. He was found to have a paralyzed right vocal cord, which was injected with Perlane and is now back in medial position. I have done 3 MBSs with him. Prior to the vocal cord injection he frankly and silently aspirated every consistency. Following the Perlane injection he penetrated every consistency (head turn and chin tuck did not change this), and only coughed twice, no aspiration. 
My question is what is causing the penetration and the lack of sensation. I'm wondering if there is something central going on, possibly from his alcohol and drug Hx. The epiglottis doesn't move as well as it should, which and RT suggested might be due to scar tissue from the ventilation and intubation/extubation. 
Does anyone have any experience or know of any studies talking about the incidence of silent aspiration with vocal cord paralysis and also with vocal cord paralysis what other factors contribute to dysphgia. 
I would appreciate any feeback!
Thanks,
Mia