Vocal Fold Paralysis — MCQs
Following total thyroidectomy, the patient develops respiratory stridor. The cause is:
Which of the following conditions is least likely to cause bilateral recurrent laryngeal nerve palsy?
A high tracheostomy may be indicated in:
A 50-year-old smoker presents with hoarseness, dysphagia, and weight loss. Flexible laryngoscopy shows a mass on the vocal cords. What is the next best step?
During thyroidectomy, which nerve, if damaged, can cause a hoarse voice?
What is the expected voice quality in a patient with bilateral abductor paralysis of the larynx?
During thyroidectomy, damage to which nerve leads to loss of high-pitched voice?
Most common nerve injured in ligation of inferior thyroid artery
Dysphonia plica ventricularis is produced from:
Which of the following is true regarding Singer's nodule?
Vocal Fold Paralysis Indian Medical PG Practice Questions and MCQs
Question 1: Following total thyroidectomy, the patient develops respiratory stridor. The cause is:
- A. Unilateral recurrent laryngeal nerve paralysis
- B. Unilateral phrenic nerve paralysis
- C. Bilateral phrenic nerve paralysis
- D. Bilateral recurrent laryngeal nerve paralysis (Correct Answer)
Explanation: ***Bilateral recurrent laryngeal nerve paralysis*** - **Bilateral recurrent laryngeal nerve paralysis** is a serious complication of total thyroidectomy, leading to **adductor paralysis** of both vocal cords. - This results in a narrowed airway, causing inspiratory **stridor**, **dyspnea**, and potentially acute respiratory obstruction requiring reintubation or tracheostomy. *Unilateral recurrent laryngeal nerve paralysis* - **Unilateral recurrent laryngeal nerve paralysis** typically causes **hoarseness** due to the inability of one vocal cord to adduct properly. - It does not usually cause **stridor** or significant respiratory distress because the other vocal cord can still compensate for airway patency. *Unilateral phrenic nerve paralysis* - **Unilateral phrenic nerve paralysis** affects one side of the **diaphragm**, causing **dyspnea** and reduced lung capacity, particularly during exertion. - It does not directly cause **stridor**, which is a sound produced by turbulent airflow through a narrowed upper airway. *Bilateral phrenic nerve paralysis* - **Bilateral phrenic nerve paralysis** causes severe **respiratory failure** due to complete paralysis of the **diaphragm**, requiring mechanical ventilation. - While life-threatening, it does not directly manifest as **stridor**, as the primary issue is the inability to move air in and out through the lower respiratory system, not an obstruction in the upper airway.
Question 2: Which of the following conditions is least likely to cause bilateral recurrent laryngeal nerve palsy?
- A. Thyroid carcinoma
- B. Lymphadenopathy
- C. Thyroid surgery
- D. Aortic aneurysm (Correct Answer)
Explanation: ***Aortic aneurysm*** - An aortic aneurysm, especially of the ascending aorta, is **less likely to cause bilateral recurrent laryngeal nerve palsy** because the left recurrent laryngeal nerve typically hooks under the aortic arch, while the right nerve hooks under the subclavian artery. - For **bilateral involvement**, two separate and simultaneous lesions affecting both nerves would be required at different anatomical locations with this etiology, making it a rare cause. *Thyroid carcinoma* - An aggressive **thyroid carcinoma** can directly invade or compress the recurrent laryngeal nerves (RLNs) due to their proximity to the thyroid gland. - If the carcinoma is extensive or multifocal, it can lead to **bilateral involvement** by affecting both nerves. *Lymphadenopathy* - Significant **cervical or mediastinal lymphadenopathy** (e.g., due to metastatic disease or lymphoma) can compress or encase both recurrent laryngeal nerves. - This proximity allows for potential **bilateral compression or damage** to the nerves as they ascend in the tracheoesophageal grooves. *Thyroid surgery* - **Thyroidectomy** is a common cause of recurrent laryngeal nerve injury due to the nerves' close anatomical relationship with the thyroid gland. - **Bilateral recurrent laryngeal nerve palsy** can occur if both nerves are damaged during dissection, often due to surgical misidentification, thermal injury, or traction.
Question 3: A high tracheostomy may be indicated in:
- A. Advanced carcinoma of the larynx
- B. Severe bilateral vocal cord paralysis (Correct Answer)
- C. Chronic scleroma involving the larynx
- D. Recurrent respiratory papillomatosis (multiple papillomatosis of the larynx)
Explanation: ***Severe bilateral vocal cord paralysis*** - **High tracheostomy** may be indicated in severe bilateral vocal cord paralysis, particularly when both cords are paralyzed in the **median (adducted) position**, causing critical airway obstruction. - A high tracheostomy is performed at the level of the **2nd or 3rd tracheal ring**, closer to the site of obstruction at the glottic level, providing immediate airway access. - This can serve as temporary relief while definitive treatments like **arytenoidectomy, cordectomy, or vocal cord lateralization** are planned. - In emergency situations, high tracheostomy or cricothyroidotomy may be life-saving. *Advanced carcinoma of the larynx* - High tracheostomy is **contraindicated** in laryngeal carcinoma as it may: - Transect through tumor tissue - Cause tumor seeding in the tracheal stoma - Compromise subsequent **total laryngectomy** procedures - **Low tracheostomy** (below the tumor, at 4th-5th tracheal ring) is the standard approach to secure the airway while avoiding tumor interference. *Chronic scleroma involving the larynx* - Scleroma typically causes **subglottic stenosis** and involves extensive tracheal disease. - **Low tracheostomy** is preferred to bypass the diseased area completely. - A high tracheostomy would be too close to the pathological process, risking inadequate airway and complications. *Recurrent respiratory papillomatosis (multiple papillomatosis of the larynx)* - Tracheostomy is generally **avoided** in RRP due to the significant risk of **seeding papillomas** into the tracheal stoma and lower airways. - Management focuses on **repeated endoscopic laser ablation** or surgical excision to preserve laryngeal function. - If tracheostomy is absolutely necessary, meticulous technique and close follow-up are required.
Question 4: A 50-year-old smoker presents with hoarseness, dysphagia, and weight loss. Flexible laryngoscopy shows a mass on the vocal cords. What is the next best step?
- A. Direct laryngoscopy with biopsy (Correct Answer)
- B. MRI of neck
- C. CT scan of neck
- D. Radiotherapy
Explanation: ***Direct laryngoscopy with biopsy*** - A definitive diagnosis of a vocal cord mass requires **histological examination** to rule out malignancy, especially given the patient's risk factors (age, smoking) and symptoms (hoarseness, dysphagia, weight loss). - **Direct laryngoscopy** allows for a thorough, magnified view of the mass and precise biopsy collection, which is superior to flexible laryngoscopy alone for definitive diagnosis and staging. *MRI of neck* - While MRI can provide excellent soft tissue detail for **staging** a known malignancy, it cannot provide a **histological diagnosis**. - It would typically be performed after a biopsy confirms malignancy to assess the extent of the tumor and potential spread. *CT scan of neck* - A CT scan is useful for evaluating **bony involvement**, lymph node status, and tumor extension for **staging purposes**, but it is not a diagnostic tool for identifying the specific type of tissue or cell pathology. - Like MRI, a CT scan would generally follow a biopsy confirming malignancy. *Radiotherapy* - **Radiotherapy** is a treatment modality for laryngeal cancer, not a diagnostic step. - Initiating treatment without a definitive histological diagnosis of malignancy would be inappropriate and potentially harmful.
Question 5: During thyroidectomy, which nerve, if damaged, can cause a hoarse voice?
- A. Recurrent laryngeal; loops under aorta/subclavian (Correct Answer)
- B. Superior laryngeal; with superior thyroid artery
- C. Glossopharyngeal; along posterior thyroid
- D. Hypoglossal; inferior to thyroid
Explanation: ***Recurrent laryngeal; loops under aorta/subclavian*** - The **recurrent laryngeal nerve (RLN)** innervates most of the intrinsic muscles of the larynx, including the **posterior crico-arytenoid muscle**, which is responsible for abducting the vocal cords. - Damage to the RLN during thyroidectomy can lead to **vocal cord paralysis**, resulting in a hoarse voice, stridor, or aspiration. *Superior laryngeal; with superior thyroid artery* - The **superior laryngeal nerve (SLN)** branches into external and internal laryngeal nerves. The **external laryngeal nerve** runs with the **superior thyroid artery** and innervates the **cricothyroid muscle**, which is responsible for tensioning the vocal cords. - Damage to the SLN can cause subtle changes in voice pitch and reduced vocal range but typically does not cause hoarseness or vocal cord paralysis, which is more characteristic of RLN injury. *Glossopharyngeal; along posterior thyroid* - The **glossopharyngeal nerve (CN IX)** provides sensory innervation to the posterior third of the tongue, tonsils, pharynx, and middle ear, and motor innervation to the stylopharyngeus muscle. - It is not directly related to vocal cord function or hoarseness as a result of thyroid surgery. *Hypoglossal; inferior to thyroid* - The **hypoglossal nerve (CN XII)** innervates all extrinsic and intrinsic muscles of the tongue, controlling tongue movement. - Damage to the hypoglossal nerve would affect speech articulation and swallowing but not directly cause hoarseness or vocal cord paralysis.
Question 6: What is the expected voice quality in a patient with bilateral abductor paralysis of the larynx?
- A. High-pitched voice (Puberphonia)
- B. Vocal fatigue (Phonasthenia)
- C. Strained voice (Dysphonia plicae ventricularis)
- D. Preserved voice quality (Normal voice) (Correct Answer)
Explanation: ***Preserved voice quality (Normal voice)*** - In **bilateral abductor paralysis**, the vocal cords are fixed in or near the midline, primarily affecting the **airway** and causing inspiratory stridor. - While breathing is severely compromised, the **vocal cords can still adduct sufficiently for phonation**, meaning the voice quality often remains largely normal, albeit with possibly reduced intensity. *High-pitched voice (Puberphonia)* - **Puberphonia** is a functional voice disorder characterized by the persistent use of a high-pitched voice after puberty, despite a normal mature larynx. - It is not directly related to laryngeal paralysis but rather a **phonatory habit or psychological cause**. *Vocal fatigue (Phonasthenia)* - **Vocal fatigue** is a symptom often associated with vocal misuse, overuse, or certain laryngeal pathologies causing inefficient vocal production. - While a patient with laryngeal paralysis might vocalize less due to respiratory distress, the paralysis itself does not directly cause vocal fatigue as a primary voice quality. *Strained voice (Dysphonia plicae ventricularis)* - **Dysphonia plicae ventricularis**, or **ventricular dysphonia**, occurs when the false vocal cords (ventricular folds) vibrate during phonation instead of or in addition to the true vocal cords, resulting in a low-pitched, harsh, or strained voice. - This condition is not a direct consequence of bilateral abductor paralysis, which primarily impacts true vocal cord movement and airway patency.
Question 7: During thyroidectomy, damage to which nerve leads to loss of high-pitched voice?
- A. External branch of the superior laryngeal nerve (Correct Answer)
- B. Hypoglossal nerve
- C. Vagus nerve
- D. Recurrent laryngeal nerve
Explanation: ***External branch of the superior laryngeal nerve*** - The **external branch of the superior laryngeal nerve** innervates the **cricothyroid muscle**, which is responsible for tensing the vocal cords. - Damage to this nerve paralyzes the cricothyroid muscle, leading to an inability to tense the vocal cords, resulting in a **monotonous voice** and **loss of high-pitched tones**. *Hypoglossal nerve* - The **hypoglossal nerve (CN XII)** controls the muscles of the **tongue**, affecting articulation and swallowing, but not vocal pitch directly. - Damage primarily causes **tongue deviation** and **difficulty with speech (dysarthria)** and swallowing. *Vagus nerve* - The **vagus nerve (CN X)** gives rise to both the **superior laryngeal nerve** and the **recurrent laryngeal nerve**. - While damage to the vagus nerve trunk would affect vocalization, the question specifically asks about loss of high-pitched voice, which points to a more localized injury to one of its branches. *Recurrent laryngeal nerve* - The **recurrent laryngeal nerve** innervates most of the intrinsic laryngeal muscles, including the **thyroarytenoid** and **posterior cricoarytenoid muscles**, primarily affecting vocal cord adduction and abduction. - Damage typically causes **hoarseness** due to vocal cord paralysis, and in severe cases, difficulty breathing, but it does not specifically lead to the *loss of high-pitched voice* as directly as superior laryngeal nerve damage.
Question 8: Most common nerve injured in ligation of inferior thyroid artery
- A. Sympathetic trunk
- B. Phrenic nerve
- C. Recurrent laryngeal nerve (Correct Answer)
- D. External branch of superior laryngeal nerve
Explanation: **Recurrent laryngeal nerve** - The **recurrent laryngeal nerve (RLN)** runs in close proximity to the inferior thyroid artery, especially on the right side, making it highly vulnerable during ligation or thyroid surgery. - Injury to the RLN can cause **hoarseness** due to paralysis of the vocal cords, as it innervates most intrinsic laryngeal muscles. *Sympathetic trunk* - The **sympathetic trunk** lies more medially and posteriorly in the neck, generally not in the immediate surgical field for inferior thyroid artery ligation. - Injury to the sympathetic trunk typically leads to **Horner's syndrome** (ptosis, miosis, anhidrosis). *Phrenic nerve* - The **phrenic nerve** courses over the anterior scalene muscle, lateral to the thyroid gland and major vessels, making it relatively safe during standard thyroid surgery. - Damage to the phrenic nerve would result in **diaphragmatic paralysis** and respiratory compromise. *External branch of superior laryngeal nerve* - The **external branch of the superior laryngeal nerve (EBSLN)** is located more superiorly, running with the superior thyroid artery to the cricothyroid muscle. - Injury to the EBSLN would affect the **pitch of the voice** but is less commonly injured during inferior thyroid artery ligation compared to the RLN.
Question 9: Dysphonia plica ventricularis is produced from:
- A. Vocal cord
- B. Ventricular fold (Correct Answer)
- C. Arytenoid
- D. Epiglottis
Explanation: ***Ventricular fold*** - **Dysphonia plica ventricularis**, also known as **ventricular dysphonia** or **false vocal cord dysphonia**, occurs when the **ventricular folds** (false vocal cords) vibrate inappropriately during phonation. - This condition often results in a **hoarse**, rough, or strained voice quality, as the false vocal cords are not designed for regular vibratory function in voice production. *Vocal cord* - The **true vocal cords** are the primary structures responsible for producing sound through precise vibration and approximation during phonation. - Dysphonia originating from the **true vocal cords** would typically be described by terms like vocal fold paralysis, nodules, or polyps, not "plica ventricularis." *Arytenoid* - The **arytenoid cartilages** are crucial in vocal cord movement and tension through their articulation with the cricoid cartilage. - While they influence voice production, they do not directly vibrate to produce sound themselves; rather, they position the vocal cords. *Epiglottis* - The **epiglottis** is a leaf-shaped cartilage that primarily functions to prevent food and liquid from entering the trachea during swallowing. - It plays no direct role in voice generation through vibration; its involvement in phonation is generally limited to resonance or protection.
Question 10: Which of the following is true regarding Singer's nodule?
- A. Laser therapy is treatment of choice
- B. It occurs at junction of anterior 1/3rd and posterior 2/3rd (Correct Answer)
- C. Requires excision as its potentially malignant
- D. Most common symptom is pain
Explanation: ***Correct: It occurs at junction of anterior 1/3rd and posterior 2/3rd*** **Singer's nodules**, also known as **vocal cord nodules**, are typically found at the junction of the **anterior one-third and posterior two-thirds** of the true vocal cords. This area experiences the most vibratory stress and contact during phonation, making it prone to trauma from vocal abuse, leading to the formation of bilateral benign lesions. *Incorrect: Laser therapy is treatment of choice* **Voice therapy** is the **first-line treatment** for Singer's nodules, aiming to modify vocal behaviors and reduce vocal strain. **Surgery**, including laser therapy or microlaryngeal excision, is reserved for cases that do not respond to conservative voice therapy and when nodules significantly impair vocal function. *Incorrect: Requires excision as its potentially malignant* Singer's nodules are **benign lesions** with no malignant potential. They are not considered premalignant and do not undergo malignant transformation. Surgical excision is considered only if voice therapy fails after adequate trial and the nodules continue to cause significant dysphonia. *Incorrect: Most common symptom is pain* The most common symptom associated with Singer's nodules is **hoarseness** or **dysphonia** (altered voice quality). The voice may sound breathy, rough, or strained. **Pain is generally not a prominent symptom** of vocal cord nodules, which helps differentiate them from other laryngeal pathologies like laryngitis or vocal cord polyps with inflammation.
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