The 'Lombard Effect' in Patients Affected by Adductor Laryngeal Dystonia

The 'Lombard Effect' in Patients Affected by Adductor Laryngeal Dystonia: a Pilot Study

Adductory spasmodic dysphonia (AdSD) is a rare condition characterised by irregular and uncontrolled voice interruptions, most commonly affecting women around the age of 45. The diagnosis is clinical and usually requires evaluation by several specialists. The exact cause is not known, but a disturbance of the motor system is hypothesised, probably related to various causes such as loss of cortical inhibition or problems with sensory input.

Neuroimaging studies have shown hyperactivity in various brain regions during speech production in patients with AdSD, but it is still unclear whether this hyperactivity is due to a malfunction of auditory and somatosensory feedback or an impairment of motor programming.

Recent research indicates that patients with AdSD show excessive muscle activation during phonation, probably due to abnormal processing of auditory feedback. This suggests that intervention in the auditory system may offer new treatment opportunities.

The proposed study aims to describe the acoustic, auditory-perceptual and subjective voice and speech changes in AdSD subjects during the Quick-Lombard Test (LT), a test that assesses vocal response under noisy conditions.

Inclusion Criteria:

• Native Italian-speaking patients;
• Normal hearing, hearing threshold < 20 dB HL for frequencies from 0.5 to 4 KHz;
• Age >18 years and <65 years;
• Written informed consent.

Exclusion Criteria:

• Non-Italian-speaking patients.
• Patients undergoing treatment for dystonia.
• Previous laryngeal surgery.
• Patient undergoing speech therapy.
• Patient undergoing dopaminergic therapy.
• Inability to sustain phonation of sufficient duration >3 seconds or to perform sufficient tests to assess vocal outcomes.
• Lack of written informed consent.