Videofluoroscopic assessment of the pathophysiology of chronic poststroke oropharyngeal dysphagia

Background and Purpose: Oropharyngeal dysphagia (OD) is a major complaint following stroke, associated with poor clinical outcome and high mortality rates. We aimed at characterizing the kinematics of swallow response associated with unsafe swallowing in chronic poststroke patients with OD. Patients and Methods: Consecutive poststroke patients with a positive volume-viscosity swallow test for OD 3 months following stroke were studied by videofluoroscopy (VFS). Demographical and clinical factors and kinematics of swallow response were compared between those poststroke patients with safe swallow (penetration-aspiration scale, PAS <= 2) and those with unsafe swallow (PAS >= 3). Receiver operating characteristic (ROC) curves were drawn for laryngeal vestibule closure (LVC) time which predicts unsafe swallow. Results: We studied 73 poststroke patients (76.7 +/- 9.3 years, 53.4% male) by VFS (60.4% with impaired safety, PAS=4.47 +/- 1.44, and 95.9% with impaired efficacy of swallow). Poststroke patients with unsafe swallow presented a poorer functional (Rankin 2.2 +/- 1.6 vs 1.2 +/- 1.0, P<.012) and nutritional status (MNA-sf <= 11, 34.2% vs 7.4%, P<.05) than poststroke patients with safe swallow. Poststroke patients with unsafe swallow presented a significant delay in LVC time (406.4 +/- 99.5 ms vs 318.9 +/- 80.4 ms; P<.05) and weaker tongue bolus propulsion forces (0.771 +/- 0.450 mJ vs 1.638 +/- 3.212 mJ; P=.043). LVC time >= 340 ms predicts unsafe swallow in chronic poststroke patients with a diagnostic accuracy of 0.78. Conclusions: Impaired safety of swallow in chronic poststroke patients is caused by specific impairments in swallow response including delayed timing of airway protection mechanisms and weak tongue propulsion forces. Treatments aiming to restore swallowing function in poststroke patients with OD should be targeted to improve these critical biomechanical events.