Voice tremor is an involuntary, rhythmic trembling of the voice. It occurs due to uncontrolled muscle movements within the throat, larynx (voice box), and vocal cords. This can manifest as variations in pitch and loudness, giving the voice a quivering or shaky sound. While severity varies, voice tremor can impact daily communication, making speech challenging and sometimes leading to interruptions or a strained vocal quality.
Essential Voice Tremor
Essential voice tremor is a common cause of involuntary voice shaking. It is a neurological disorder, often with a genetic component, and distinct from Parkinson’s disease. This tremor typically appears during speech as an action tremor, rather than at rest. Its main symptom is rhythmic voice wavering, which can affect vocal folds and surrounding muscles in the mouth and throat.
This tremor can also co-occur with essential tremor in other body parts, such as the head or hands. Its underlying mechanisms involve dysfunction within the cerebellum and basal ganglia, brain regions responsible for coordinating muscle movement. Disruption in these areas, which regulate motor control, can lead to the rhythmic oscillations observed in the voice. While the exact cause is not fully understood, it is believed to stem from abnormal nerve signals in these brain areas.
Essential voice tremor can affect people of any age, but it most commonly begins in individuals in their 50s or 60s. In nearly half of all cases, it is inherited, and its severity can increase with age. Rhythmic changes in loudness and pitch are consistently present during vocalization. Even in mild cases, a minor quavering might be noticeable, while more severe tremors can lead to significant interruptions in sound production.
Other Neurological Conditions
Beyond essential voice tremor, several other neurological conditions can contribute to voice tremors. Parkinson’s disease, a progressive neurological disorder, is one such condition. Unlike the action tremor seen in essential tremor, Parkinson’s voice tremor can sometimes present as a resting tremor, though it primarily manifests during speech. Voice changes in Parkinson’s also include reduced loudness, a monotone quality, and sometimes a hoarse voice, alongside tremor.
Dystonia, particularly laryngeal dystonia, is another neurological disorder causing voice tremors. Laryngeal dystonia involves involuntary muscle contractions of the larynx, leading to voice breaks, a strained or strangled vocal quality, and sometimes a shaky voice. These contractions are often sustained or repetitive, resulting in abnormal postures or movements. The tremor in laryngeal dystonia results from spasmodic muscle actions within the voice box.
Multiple sclerosis (MS) and stroke can also induce voice tremors, though they are less common causes than essential tremor or Parkinson’s disease. In MS, nerve damage in the brain and spinal cord can disrupt signals controlling vocal muscles, leading to uncoordinated movements and tremor. Similarly, a stroke, which damages brain tissue, can impact neural pathways for speech and voice control, potentially causing voice tremor as part of broader motor speech deficits. These conditions affect the brain’s ability to send precise signals to the vocal apparatus, leading to involuntary voice fluctuations.
Non-Neurological Factors
Voice tremors are not exclusively linked to neurological disorders; several non-neurological factors can also contribute. Hyperthyroidism, where the thyroid gland produces too much hormone, can cause fine tremors throughout the body, affecting the voice. Excess thyroid hormones increase metabolic rate, heightening nervous system activity and resulting in muscle instability, manifesting as vocal quivering. This systemic effect can disrupt the fine motor control required for steady voice production.
Anxiety and stress represent another common non-neurological influence on voice quality. Heightened physiological arousal, a natural response to stress, can cause increased muscle tension, particularly in the vocal cords and surrounding throat muscles. This tension can lead to an unsteady or shaky voice, as the muscles struggle to maintain smooth, controlled movements during speech. The body’s “fight or flight” response can inadvertently impact vocal stability, making the voice sound tremulous.
Certain medications can also have voice tremor as a side effect. For instance, some bronchodilators, used for respiratory conditions, can stimulate the nervous system and induce tremors, including vocal ones. Similarly, specific antidepressants and mood stabilizers, which alter brain chemistry, can sometimes lead to motor side effects manifesting as vocal instability. These medications can interfere with the delicate balance of neurotransmitters or directly affect muscle control, causing the voice to waver.
Beyond medical conditions and medications, vocal overuse or fatigue can temporarily contribute to voice tremors. Prolonged or strenuous vocalization can strain the laryngeal muscles, leading to fatigue and reduced control. This can result in a less steady voice, as tired muscles struggle to maintain consistent pitch and volume. While not a cause of chronic tremor, acute vocal fatigue can temporarily mimic aspects of a tremulous voice, especially after extended periods of speaking or singing.