From the Guidelines
Neurological conditions are a significant cause of voice changes and laryngeal dysfunction, and early diagnosis and multidisciplinary management are crucial for optimal outcomes. Neurological conditions can impact voice quality and laryngeal function through disruption of the complex neural pathways controlling vocal fold movement. The most common neurological causes include Parkinson's disease, which produces a soft, monotone voice with reduced volume; multiple sclerosis, causing vocal fatigue and tremor; amyotrophic lateral sclerosis (ALS), leading to progressive weakness and eventual dysarthria; stroke, which may cause unilateral vocal fold paralysis if the vagus nerve is affected; myasthenia gravis, presenting with progressive vocal fatigue; and essential tremor, resulting in a wavering voice quality 1. Other conditions include spasmodic dysphonia (laryngeal dystonia), characterized by strained, strangled voice breaks; Huntington's disease, with irregular vocal patterns; and iatrogenic nerve damage from surgical procedures near the recurrent laryngeal nerve.
Some key points to consider in the management of neurological causes of voice changes and laryngeal dysfunction include:
- Early diagnosis and multidisciplinary management involving neurologists, otolaryngologists, and speech-language pathologists are essential for optimal outcomes 1
- Treatment approaches vary by condition but may include voice therapy, medication management (such as levodopa for Parkinson's disease or botulinum toxin injections for spasmodic dysphonia), and surgical interventions for vocal fold paralysis
- Patients with head and neck cancer may present with dysphonia, and failure to evaluate the larynx can delay cancer diagnosis, resulting in higher staging, need for more aggressive treatment, and reduced survival rates 1
- Prevalence of dysphonia within these conditions varies, and not all patients with a particular condition will manifest with dysphonia 1
In summary, a comprehensive approach to diagnosis and management is necessary to address the complex needs of patients with neurological causes of voice changes and laryngeal dysfunction, and this should be guided by the most recent and highest quality evidence available 1.
From the Research
Neurological Causes of Voice Changes and Laryngeal Dysfunction
- Neurological disorders can affect laryngeal function, leading to voice changes and laryngeal dysfunction, as discussed in 2, 3.
- Parkinson's disease is a common neurological disorder that can cause voice changes and laryngeal dysfunction, with studies suggesting that voice dysfunction may be an early sign of motor impairment in Parkinson's disease 4.
- Other neurological disorders that can affect laryngeal function include essential tremor, stroke, amyotrophic lateral sclerosis, multiple sclerosis, and dystonia 2.
- Laryngeal physiology is complex and depends on dynamic neuromuscular forces acting on a basic framework of cartilage and specialized soft tissues, making it susceptible to disruption by neurologic disorders 3.
Specific Neurological Disorders Affecting the Larynx
- Parkinson's disease can cause bilateral vocal cord palsy, laryngeal spasms, and dystonia of the supra-laryngeal muscle, leading to stridor and upper airway obstruction 5.
- Levodopa administration has been shown to improve lung function and symptoms of parkinsonian syndrome, including stridor and voice changes 5.
- Bilateral vocal cord paralysis in Parkinson's disease may be a manifestation of advanced disease, and may be seen more commonly in the future as therapy enables more patients to live longer 6.
Diagnosis and Treatment of Neurological Disorders Affecting the Larynx
- Diagnosis of neurologic disease is primarily based on history and physical examination, with evaluation of laryngeal function including listening to the voice, systematic observation of the larynx during speech and nonspeech tasks, and sometimes ancillary tests 2.
- Otolaryngology consultation is important in the diagnosis and treatment of neurologic disorders that affect laryngeal function, with the otolaryngologist able to perform a systematic evaluation of laryngeal and pharyngeal function 2.