Cortical-Basal Ganglia-Cerebellar Networks in Unilateral Vocal Fold Paralysis: A Pilot Study.

OBJECTIVES/HYPOTHESIS: To evaluate differences in cortical-basal ganglia-cerebellar functional connectivity between treated unilateral vocal fold paralysis (UVFP) and healthy control cohorts using resting-state functional magnetic resonance imaging (RS-fMRI). STUDY DESIGN: Cross-sectional. METHODS: Ten UVFP study patients treated by type I thyroplasty and 12 control subjects underwent RS-fMRI on a 3-Tesla scanner to evaluate differences in functional connectivity of whole-brain networks. Spontaneous RS-fMRI data were collected using a gradient echo planar pulse sequence, preprocessed, and analyzed to compare seed-to-voxel maps between the two cohorts. Seeds were placed in the caudate, putamen, and globus pallidus divisions of the basal ganglia in both hemispheres. Group contrasts were tested for statistical significance using two-tailed unpaired t tests corrected for multiple comparisons with a cluster false discovery rate threshold of P < .05. RESULTS: UVFP patients demonstrated increased connectivity between both caudate nuclei and the precuneus, a node of the default mode network, compared to healthy controls. Both caudate nuclei also showed decreased connectivity with the left cerebellar hemisphere. The putamen and globus pallidus divisions of the basal ganglia were not abnormally connected to other brain structures. CONCLUSIONS: UVFP patients treated by type I thyroplasty exhibited long-term alterations of cortical-basal ganglia-cerebellar networks thought to be important for self-referential voice quality awareness and learning processes that compensate for changes to the paralyzed hemilarynx. This pilot study on relatively small cohorts adds to growing evidence for persistent central nervous system changes in treated UVFP. Replication studies with larger numbers of subjects will be essential to validate and extend findings. LEVEL OF EVIDENCE: 3b Laryngoscope, 130:460-464, 2020.

Vocal motor control and central auditory impairments in unilateral vocal fold paralysis.

OBJECTIVES: To evaluate differences in vocal motor control and central auditory processing between treated unilateral vocal fold paralysis (UVFP) and healthy control cohorts. STUDY DESIGN: Cross-sectional. METHODS: Ten UVFP study patients treated by type I thyroplasty with stable voices were compared to 12 control subjects for vocal motor control using a pitch perturbation response task and central auditory processing performance using a battery of complex sound intelligibility assays that included adverse temporal and noise conditions. Standard clinical evaluations of voice production and peripheral audiometric sensitivity were performed. RESULTS: Vocal motor control was impaired in treated UVFP. The UVFP cohort exhibited a 32.5% reduction in the instantaneous, subconscious compensatory response to pitch feedback perturbation in the interval between 150 ms and 550 ms following onset (P < 0.0001, linear mixed effects model). This impairment cannot simply be ascribed to vocal motor capacity insufficiency in the UVFP cohort because both cohorts demonstrated comparable functional capacity to perform the vocal motor task. The UVFP cohort also showed greater propensity for central auditory processing impairment (P < 0.05), notably for temporal compression and added noise challenges. CONCLUSION: Combined central vocal motor control and auditory processing impairments in treated UVFP highlight reciprocal interdependency of sensory and motor systems. This pilot study suggests that peripheral motor impairment of the larynx can degrade central auditory processing, which in turn may contribute to vocal motor control impairment. A more complete restoration communicative function in UVFP will require deeper understanding of sensory, motor, and sensorimotor aspects of the human communication loop. LEVEL OF EVIDENCE: 3b Laryngoscope, 129:2112-2117, 2019.

Cortical networks for speech motor control in unilateral vocal fold paralysis.

OBJECTIVE: To evaluate brain networks for motor control of voice production in patients with treated unilateral vocal fold paralysis (UVFP). STUDY DESIGN: Cross-sectional comparison. METHODS: Nine UVFP patients treated by type I thyroplasty, and 11 control subjects were compared using magnetoencephalographic imaging to measure beta band (12-30 Hz) neural oscillations during voice production with perturbation of pitch feedback. Differences in beta band power relative to baseline were analyzed to identify cortical areas with abnormal activity within the 400 ms perturbation period and 125 ms beyond, for a total of 525 ms. RESULTS: Whole-brain task-induced beta band activation patterns were qualitatively similar in both treated UVFP patients and healthy controls. Central vocal motor control plasticity in UVFP was expressed within constitutive components of central human communication networks identified in healthy controls. Treated UVFP patients exhibited statistically significant enhancement (P < 0.05) in beta band activity following pitch perturbation onset in left auditory cortex to 525 ms, left premotor cortex to 225 ms, and left and right frontal cortex to 525 ms. CONCLUSION: This study further corroborates that a peripheral motor impairment of the larynx can affect central cortical networks engaged in auditory feedback processing, vocal motor control, and judgment of voice-as-self. Future research to dissect functional relationships among constitutive cortical networks could reveal neurophysiological bases of central contributions to voice production impairment in UVFP. Those novel insights would motivate innovative treatments to improve voice production and reduce misalignment of voice-quality judgment between clinicians and patients. LEVEL OF EVIDENCE: 3b Laryngoscope, 129:2125-2130, 2019.