Neuroanatomical Correlates of Hypophonia in Subcortical Vascular Cognitive Impairment

Early detection and intervention may alter the disease course of subcortical vascular cognitive impairment (SVCI). Patients with SVCI have white matter ischemia that disrupts connections between the cortex and subcortical gray matter and therefore manifest various symptoms such as motor disturbances and behavioral/cognitive dysfunction. Reduced vocal loudness, or hypophonia, is one of the common motor symptoms of SVCI, but few studies have systematically investigated it in this patient population. The main purpose of this investigation was to identify neural pathways underlying hypophonia in patients with SVCI.

Eighty-eight patients with SVCI and 21 normal controls performed phonation tasks. Diffusion tensor imaging data from 73 patients were utilized to measure white matter changes associated with hypophonia.

Correlational analyses between white matter fractional anisotropy values and the decibel level of the "sustained phonation" task identified the left midbrain cerebral peduncle (corticobulbar tract), external capsule, corona radiata/internal capsule, and bilateral frontal white matter as possible neural correlates for hypophonia.

Our results support the notion that hypophonia in SVCI patients might be caused by the impairment of the pyramidal and extrapyramidal systems. This study provides a unique contribution towards understanding the neuropathology of hypophonic features in this population.