Investigations
1st investigations to order
laryngoscopy
Test
Mainstay of diagnosis.
Can be performed by the use of a rigid or flexible laryngoscope.
Performed if the patient presents initially to an otolaryngology specialist, but most primary care physicians are not experienced in the technique and diagnose most cases of viral laryngitis clinically.
Some primary care physicians may use mirror indirect laryngoscopy, depending on experience.
Result
acute infectious laryngitis: oedema and erythema of the true vocal folds; thick, copious, white-yellow secretions in the glottis; chronic tuberculous laryngitis: exophytic or nodular laryngeal lesions commonly involving the posterior glottis; reflux laryngitis: no exudative changes in the larynx, may show hyperaemia of the arytenoids and the posterior true vocal folds
Investigations to consider
biopsy
Test
Biopsies should be obtained in cases where tuberculosis is suspected.
Procedure is usually performed with a general anaesthetic.
Result
chronic tuberculous laryngitis: granulomatous necrosis, positive stain for acid-fast bacilli
oropharyngeal cultures
Test
Cultures should be obtained if bacterial infection, diphtheria, or TB are suspected.
Loeffler or Tindale selective media are used when diphtheria is suspected.[24]
Result
positive cultures in bacterial infection
nasal swab for culture
Test
Cultures should be obtained if diphtheria is suspected.
Loeffler or Tindale selective media are used when diphtheria is suspected.[24]
Result
positive cultures in bacterial infection
serum immunoprecipitation or polymerase chain reaction for diphtheria
Test
Definitive diagnosis of diphtheria can also be made by the demonstration of toxin production.
Result
positive in diphtheria
full blood count
Test
May be performed if acute bacterial infection is suspected.
Result
may be a leukocytosis with left shift in bacterial infection
rapid antigen detection test
Test
May be performed if bacterial laryngitis due to group A streptococcal infection is suspected.
Result
positive in bacterial infection
chest x-ray
Test
Should be obtained in cases where tuberculosis is suspected.
Result
cavitary lesions in tuberculosis
sputum cultures
Test
Performed routinely in patients with suspected tuberculosis.
Result
may be positive for mycobacteria in cases of tuberculosis
videostroboscopy
Test
Hoarseness is not always due to laryngitis, and therefore careful examination using videostroboscopy to evaluate the vocal folds and rule out a more serious vocal fold injury (haemorrhage or vocal mucosal tear) in heavy voice users is essential.
Videostroboscopy allows for simultaneous evaluation of voice quality, laryngeal anatomy, and vocal fold vibratory function.[23]
Guidelines on dysphonia encourage the use of videostroboscopic examination when the voice symptoms are out of proportion to the indirect laryngoscopy.[22]
Result
reveals vocal fold sulcus or vibratory pathologies such as stiffness, or helps differentiate between benign vocal lesions
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