Understanding Drug-Induced Vocal Cord Paralysis
Vocal cord paralysis occurs when the nerve impulses to the larynx (voice box) are disrupted, preventing the normal movement of one or both vocal cords [1.3.7, 1.3.4]. While often caused by surgery, tumors, or viral infections, a lesser-known cause is iatrogenic, meaning it is caused by medical treatment. Certain medications can lead to vocal cord paralysis or paresis (weakness) through various mechanisms, most notably neurotoxicity, which involves damage to the nerves controlling the larynx, such as the recurrent laryngeal nerve [1.3.2, 1.5.4]. Other drugs may not cause true paralysis but can lead to significant vocal changes, such as dysphonia (hoarseness), by causing dryness, muscle weakness (myopathy), or irritation [1.6.1, 1.3.5].
Key Medications Associated with Vocal Cord Paralysis
Several classes of drugs have been identified in medical literature as potential causes of vocal cord paralysis or significant dysfunction. The link is often rare but well-documented.
Chemotherapy Agents: The Strongest Link
Chemotherapeutic drugs are among the most cited medications for causing vocal cord paralysis due to their neurotoxic potential [1.3.2, 1.4.2].
- Vinca Alkaloids: Vincristine is a prominent example, widely used in treating leukemias and other cancers [1.5.1, 1.5.3]. It is known to interfere with microtubule formation, disrupting nerve cell function and leading to primary axonal degeneration [1.5.3]. VCP induced by vincristine can be bilateral or unilateral and is often reversible upon discontinuation of the drug [1.5.2, 1.5.5].
- Platinum-Based Drugs and Taxanes: Medications like Carboplatin, Oxaliplatin, and Paclitaxel are also implicated [1.2.1, 1.3.2]. These drugs can induce peripheral neuropathy that may, in rare cases, affect the laryngeal nerves, particularly at higher cumulative doses [1.3.2]. The neurotoxicity can result from mitochondrial dysfunction and oxidative stress [1.3.2].
Inhaled Corticosteroids and Vocal Fold Myopathy
While not typically causing complete paralysis, inhaled corticosteroids (ICS) used for asthma and COPD are a very common cause of dysphonia (hoarseness) [1.2.2, 1.6.2].
- Mechanism: The leading theory is that deposition of the steroid in the oropharynx causes a localized muscle weakness or myopathy in the vocal cords [1.6.1, 1.6.2]. This can result in hypotonus of the vocal cords, making proper phonation difficult [1.6.2]. The effect is often dose-dependent and reversible after stopping the medication [1.6.2]. Examples include fluticasone and beclomethasone [1.2.6].
- Prevention: Using a spacer, rinsing the mouth after inhalation, and using the lowest effective dose can help minimize this side effect [1.6.1, 1.6.3].
Other Implicated Medications
Other drug classes have been reported to cause vocal changes, though true paralysis is less common than with chemotherapy agents.
- ACE Inhibitors: Used for hypertension, drugs like Captopril and Enalapril can induce a persistent cough in up to 10% of patients, which can lead to vocal cord lesions, hoarseness, and in rare cases, aphonia (loss of voice) [1.3.3, 1.4.6].
- Antihistamines and Diuretics: These medications can dry out the protective mucosal layer of the vocal cords [1.2.7, 1.4.8]. Dehydrated vocal cords are stiff, less pliable, and more prone to injury and irritation, leading to a strained or hoarse voice [1.2.5, 1.3.3].
- Miscellaneous Drugs: Ropinirole (used for Parkinson's disease) and Mycophenolate have been listed as having vocal cord paralysis as a potential side effect [1.2.1]. Tricyclic antidepressants like amitriptyline have also been reported to cause hoarseness [1.4.2].
Comparison of Drug-Induced Vocal Issues
| Drug Class | Examples | Primary Vocal Effect | Mechanism of Action |
|---|---|---|---|
| Vinca Alkaloids | Vincristine | Paralysis (often bilateral) | Neurotoxicity, disruption of axonal transport [1.5.3] |
| Platinum/Taxane Agents | Carboplatin, Paclitaxel | Paralysis or Paresis | Neurotoxicity, mitochondrial dysfunction [1.3.2] |
| Inhaled Corticosteroids | Fluticasone, Budesonide | Dysphonia (Hoarseness) | Localized myopathy (muscle weakness) [1.6.1, 1.6.2] |
| ACE Inhibitors | Captopril, Enalapril | Cough, Hoarseness | Induction of cough leading to vocal trauma [1.4.6, 1.3.3] |
| Antihistamines/Diuretics | Claritin, Hydrochlorothiazide | Hoarseness, Vocal Strain | Dehydration of vocal cord mucosa [1.2.7, 1.2.5] |
Diagnosis and Management
A new onset of hoarseness, stridor (a high-pitched breathing sound), or breathiness in a patient on a potentially causative medication should raise suspicion [1.5.1]. The primary diagnostic tool is a laryngoscopy, which allows an otolaryngologist to visualize the movement of the vocal cords [1.5.3]. If drug-induced VCP is confirmed, management often involves a multidisciplinary approach. The first step is typically to stop or reduce the dosage of the offending drug, if medically feasible [1.5.2, 1.5.4]. Vocal cord function often recovers over weeks to months after cessation of the drug [1.5.2]. In severe cases, especially with bilateral paralysis causing airway obstruction, interventions like a tracheostomy may be required to secure the airway [1.5.2].
Conclusion
While iatrogenic vocal cord paralysis from medication is uncommon, it is a critical adverse event to be aware of, particularly with certain chemotherapy drugs like vincristine. Many other common medications, especially inhaled corticosteroids, can cause significant dysphonia through different mechanisms. Prompt recognition of symptoms, a thorough review of the patient's medications, and an otolaryngology consultation are essential for accurate diagnosis and management, which can often lead to the reversal of symptoms.
For more detailed information on laryngeal disorders, consider visiting the Merck Manual for Professionals.
