Related Experiment Video
Updated: Jan 24, 2026

Training Synesthetic Letter-color Associations by Reading in Color
Published on: February 20, 2014
The extrinsic risk and its association with neural alterations in spasmodic dysphonia
Laura de Lima Xavier1, Kristina Simonyan1
1Department of Otolaryngology, Massachusetts Eye and Ear, Boston, MA, USA; Department of Neurology, Massachusetts General Hospital, Boston, MA, USA; Harvard Medical School, Boston, MA, USA.
Introduction:
Spasmodic dysphonia (SD) is an isolated focal dystonia characterized by laryngeal spasms during voluntary voice production. Environmental factors have been assumed to play a role in SD pathophysiology; however, the exact extrinsic risk factors and their association with neural alterations remain unknown.
Methods:
A total of 186 SD patients and 85 healthy controls completed a structured 177-question survey, consisting of questions on general biographical information, medical history, symptomatology of dystonia. Data were imputed in a stepwise regression model to identify extrinsic risk factors for SD. In addition, functional MRI data from a subset of this cohort were analyzed to determine brain activation abnormalities associated with the SD extrinsic risk.
Results:
We found that (1) recurrent upper respiratory infections, gastroesophageal reflux, and neck trauma, all of which influence sensory feedback from the larynx, represent extrinsic risk factors, likely triggering the manifestation of SD symptoms, and (2) neural alterations in the regions necessary for sensorimotor preparation and integration are influenced by an extrinsic risk in susceptible individuals.
Conclusions:
These findings provide evidence for the extrinsic risk in SD development and demonstrate the link with alterations in the sensorimotor preparatory network that collectively contribute to the multifactorial pathophysiology of SD.
Related Concept Videos
The Extrinsic Apoptotic Pathway
Extrinsic and Intrinsic Pathways of Hemostasis
The Extrinsic Pathway
The extrinsic pathway of coagulation is typically initiated by tissue damage that exposes blood to tissue factor (TF), a protein released by the damaged tissue cells outside the blood vessels—this interaction with TF triggers biochemical reactions involving specific clotting factors. The key player here is Factor VII, which...
Alterations in Respiration II
In Biot's breathing, the respiratory rate and depth are irregular, alternating between periods of deep gasping and apnea. Common causes...
Altered States of Awareness
The ingestion of substances like stimulants or hallucinogens leads to chemical alterations in the brain...
Relative Risk
Association Areas of the Cortex
Prefrontal Association Area: This area is located in the frontal lobe and is involved in planning, decision-making, and moderating social behavior. It connects with primary motor areas,...

