What is a vocal fremitus test?
Vocal Fremitus Test, When a person speaks, the vocal cords create feelings (vocal thrill) in the tracheobronchial tree and through the lungs and chest wall, where they can be touched (tactile thrill). This is usually assessed with the healthcare provider by placing the palm on the chest wall and then asking the patient to repeat a phrase that contains low-frequency vowels, such as “blue balloons” or “children’s toys.” (The original diphthong used was the German word neunundneunzig but the English translation ‘ninety-nine’ was a higher frequency diphthong and therefore was not as effective at inducing thrill).
An increase in tactile thrill indicates denser or inflamed lung tissue, which can be caused by conditions such as pneumonia. A decrease suggests air or fluid in the pleural spaces or a decrease in the density of lung tissue, which can be caused by conditions such as chronic obstructive pulmonary disease or asthma.
Types of vocal fremitus test
The pleural thrill is a palpable vibration of the chest wall caused by friction between the parietal and visceral pleura of the lungs. See pleural friction rub for the aural analog of this sign.
Fremitus appears when the teeth move. This can be assessed by feeling and looking at the teeth when the mouth is open and closed.
Periodontal thrill occurs in any of the alveolar bones when an individual suffers trauma from occlusion. It is the result of teeth exhibiting at least slight mobility rubbing against the adjacent walls of their alveoli, the volume of which has been slightly expanded by inflammatory responses, bone resorption, or both. As a test to control the severity of the periodontal disease, the patient is told to close his mouth at all-out intercuspation and is asked to grind his teeth slightly. Fingers located in the labial vestibule against the alveolar bone can notice the thrill.
The hoarse thrill, also known as the bronchial thrill, is a palpable vibration produced during breathing caused by a partial obstruction of the airways. The obstruction may be due to mucus or other secretions in the airways, bronchial hyperresponsiveness, or tumors. See rhonchus (rhonchi) for the auditory equivalent of this sign.
The tactile thrill, known by many other names, including the pectoral thrill, the tactile vocal thrill, or simply the vocal thrill, is a vibration felt in the patient’s chest during low-frequency vocalization. The patient is usually asked to repeat a phrase while the examiner feels the vibrations by placing a hand on the patient’s chest or back. Usually used phrases in English include ‘boy oh boy’ and ‘toy boat’ (diphthong phrases), as well as ‘blue balloons’ and ‘Scooby-Doo’. “Ninety-nine” is classically included, however, this is a misinterpretation of the original German report, in which “neunundneunzig” was the chosen low-frequency diphthong.
The tactile thrill is usually more intense in the second right intercostal space, as well as in the interscapular area since these areas are neighboring to the bronchial trifurcation (right side) or bifurcation (left side). The tactile thrill is pathologically increased in areas of consolidation and decreased or absent in areas of pleural effusion or pneumothorax (when there is air outside the lung in the chest cavity, preventing lung expansion).
The reason for the increased thrill in a combined lung is the fact that sound waves are transmitted with less decay in a solid or fluid medium (the consolidation) than in a gaseous medium (aerated lung). On the contrary, the aim for the decrease in the thrill in a pleural outpouring or pneumothorax (or any pathology that separates the lung tissue from the body wall) is that this increase in space reduces or completely prevents the transmission of sound.
It has recently been suggested that artifacts caused by eliciting tactile thrill during breast ultrasound can be used to differentiate between benign and malignant tumors.
The tussive thrill is a vibration felt in the chest when the patient coughs.
The pericardial thrill is a vibration that is felt in the chest wall due to the friction of the pericardial exteriors against each other. See pericardial friction rub for the aural analog of this sign.
Hydatid thrill is a vibratory sensation that is felt when palpating a hydatid cyst.
Exam method for vocal fremitus test
Before palpating the back of the chest for a tactile thrill, the patient is asked to cross his arms over the chest wall to displace both scapulae. The patient is asked to repeat “ninety-nine” or “one, two, three” in a constant tone while the physician simultaneously palpates the chest wall on both sides, using the ulnar edge of the hand or the palmar base. Palpation begins with the apex of the lung and moves to the same place on the opposite side of the chest wall. The vibrations perceived on both sides are compared as the hands move from the apex to the base of the lung, covering the entire posterior chest wall. The same maneuver is repeated on the anterior and lateral walls of the thorax.
Causes of increased vocal resonance
- Lung cancer
Causes of reduced vocal resonance
- Pleural effusion