Pathological Correlates of Nonverbal Oral Apraxia in the Neurodegenerative Disease
Danna Garcia-Guaqueta1, Joseph Duffy1, Heather Clark1, Rene Utianski1, Hugo Botha1, Julie Stierwalt1, Mary Machulda2, Jennifer Whitwell3, Keith Josephs1
1Department of Neurology, 2Department of Psychiatry and Psychology, 3Department of Radiology, Mayo Clinic
Objective:
To describe the pathological associations of nonverbal oral apraxia (NVOA) and determine whether the onset and severity of NVOA differ according to underlying pathology.
Background:
NVOA is the inability to perform voluntary oromotor movements due to impaired program planning and sequencing. It is associated with apraxia of speech, aphasia, and ideomotor apraxia. However, it remains unclear whether it is linked to a specific underlying pathology.
Design/Methods:
We conducted a retrospective study in 63 autopsy-confirmed patients with NVOA which was assessed through the NVOA evaluation tool. A cutoff of 29 was used to define presence of NVOA. Autopsy diagnoses were grouped as 4R tauopathies (progressive supranuclear palsy (PSP) or cortical basal degeneration (CBD)), and other pathologies. We compared baseline characteristics by group. We defined an optimal cut-point for the NVOA scores at baseline and for the first abnormal score to distinguish CBD from PSP using the Youden index method.
Results:
Seventy percent of the patients had a 4R tauopathy: PSP (36.5%) and CBD (33.3%). Patients with other pathologies had a shorter median time from onset to abnormal NVOA scores (3.2 vs 4.9 years, p=0.028). At baseline, patients with CBD had the lowest (worst affected) median NVOA scores (21/32), while those with PSP had the highest (29/32) (p=0.04), with an optimum cutpoint of 24 able to distinguish CBD from PSP with 62% sensitivity and 78% specificity. Patients with CBD also had worse first abnormal NVOA scores, with an optimum cut-point of 19 able to distinguish CBD from PSP with 67% sensitivity and 74% specificity.
Conclusions:
NVOA was most associated with 4R tauopathies, although it occurred later in the disease in 4R tauopathies than in other pathologies. Severity of NVOA was worse in those with CBD, and a cut-point score of 24 at baseline can help distinguish CBD from PSP with a relatively high sensitivity and specificity.