Characterizing the Normative Voice Tremor Frequency in Essential Vocal Tremor

Area of Science:

• Neurology
• Otolaryngology
• Speech-Language Pathology

Background:

• Essential vocal tremor (EVT) is a neurologic voice disorder causing pitch and loudness fluctuations.
• Accurate diagnosis and understanding of EVT mechanisms are hindered by a lack of defined normative tremor frequency ranges.

Purpose of the Study:

• To characterize the normative voice tremor frequency in patients with essential vocal tremor (EVT).

Main Methods:

• A cross-sectional observational study involving 160 patients diagnosed with EVT at a tertiary voice center.
• Three methods were employed to measure tremor frequency: perceptual assessment, computerized peak detection, and laryngeal electromyography.
• Tremor frequencies were compared across modalities to ensure reliability and establish normative ranges.

Main Results:

• The median essential vocal tremor (EVT) frequency was consistently between 4 and 5 Hz across all measurement methods.
• The normative tremor frequency range for EVT, encompassing all interquartile ranges, was determined to be 3.8 to 5.5 Hz.
• Mean differences between measurement methods were clinically insignificant, indicating high consistency.

Conclusions:

• This study establishes the largest dataset to date for characterizing essential vocal tremor (EVT) frequency.
• The defined normative range (3.8-5.5 Hz) is narrower than previously reported, aiding in EVT diagnosis.
• Frequencies outside this range warrant further investigation for alternative causes of vocal tremor, improving diagnostic accuracy.