Cannabis Inhalation and Voice Disorders: A Systematic Review

Question  What is the association between cannabis inhalation and voice disorders?

Findings  In this systematic review of 6 human studies and 13 basic science and animal studies, cannabis inhalation was associated with dark vocal folds on laryngoscopy as well as respiratory symptoms and negative lung function changes attributable to degradation by-products generated during smoke exposure, especially in large doses. Cessation of cannabis consumption or changing to vaporizing methods was associated with improved respiratory symptoms and lung function changes.

Meaning  The findings suggest that practitioners managing voice disorders should gather details about patterns of cannabis consumption and that cannabis smokers with a voice disorder should undergo laryngeal imaging and complete lung function testing when dyspnea is present and receive education about the potential negative effects of inhalation.

Importance  Widespread legalization of cannabis throughout the United States has created a knowledge gap that leaves practitioners who manage voice disorders uninformed about this substance, commonly referred to as marijuana. The association of cannabis inhalation and voice disorders is rarely reported. However, studies on the association between cannabis inhalation and respiration have been published; therefore, these studies may serve as a surrogate for studies on the association between cannabis and phonation.

Objective  To review the literature on the association of cannabis-only consumption via smoking and vaping with the health and function of the vocal mechanism to aid clinical recommendations for patients with voice disorders.

Evidence Review  This systematic review adhered to the Preferred Reporting Items for Systematic Reviews and Meta-analyses statement. An electronic search in MEDLINE via PubMed, CINAHL, Scopus, and Cochrane Library databases for original research on inhaled cannabis was performed from January 1, 2007, through August 10, 2018. The search strategy included Medical Subject Heading terms and keywords marijuana, cannabis, respiratory, lungs, larynx, voice, phonation, and vocal with Boolean operators (AND, OR). Studies of participants of legal age (≥18 years) who had cannabis-only clinical data and used nonsynthetic cannabinoids were included in the review.

Findings  This systematic review identified 6 clinical science studies and 13 basic science or animal studies. The only study to date that has evaluated the association between laryngeal symptoms and inhaling cannabis found that human smokers assessed by indirect laryngoscopy with mirror examination exhibited dark vocal folds. Analyses of 6 other clinical science articles indicated an association between cannabis inhalation and respiratory problems that were reduced with smoking cessation or switching to vaporizing. Lung function was maintained in light cannabis smoke exposure after long-term use. Analyses of basic science and animal articles indicated that cannabis smoking was associated with lung and throat injuries attributable to smoking degradation by-products, similar to injuries seen in human tobacco smoking.

Conclusions and Relevance  The findings suggest that cannabis-only smoking is associated with changes in vocal fold appearance, respiratory symptoms, and negative lung function changes, especially in heavy smokers. Details about patterns of cannabis consumption appear to be relevant to gather in patients with voice disorders. Results further suggest that cannabis smokers presenting with a voice disorder should undergo laryngeal imaging and complete pulmonary function testing when indicated and receive education about consumption methods and their association with voice disorders.