Which condition presents 'lock jaw' as the clinical feature?

Appeared in: DSSSB -28 August 2019 (Shift-2)

Explanation

'Lock jaw,' medically known as trismus, is the classic and most common initial symptom of Tetanus.
It is caused by the neurotoxin tetanospasmin, produced by Clostridium tetani, which leads to sustained, painful spasms of the masseter (jaw) muscles.
The toxin blocks the release of inhibitory neurotransmitters like glycine and GABA in the central nervous system, resulting in unopposed muscle contraction and rigidity.
Other characteristic signs include risus sardonicus (a sardonic smile) and opisthotonus (arching of the back).

Option B: Tuberculosis is a bacterial infection primarily affecting the lungs. Its classic symptoms are a persistent cough, fever, night sweats, and weight loss. It does not cause muscle spasms or lock jaw.
Option C: Pertussis, or whooping cough, is a respiratory infection known for severe, uncontrollable coughing fits that end in a high-pitched 'whoop' sound. It does not cause trismus.
Option D: Rabies is a viral disease that affects the central nervous system. Its hallmark symptoms include hydrophobia (fear of water), aerophobia, and agitation. While pharyngeal spasms can occur, making swallowing difficult, the classic 'lock jaw' presentation is not characteristic of rabies.

Clinical Relevance

Nursing practice connection: Use the key finding related to Clinical manifestation of Tetanus to guide bedside assessment, documentation, and the next nursing action.
Prompt recognition of lock jaw is critical for the early diagnosis and treatment of Tetanus, which is a medical emergency with a high mortality rate if left untreated.
Nursing care for a patient with Tetanus is intensive, focusing on managing painful muscle spasms, maintaining a patent airway (often requiring mechanical ventilation), and providing a quiet, non-stimulating environment.
A key nursing role is in prevention through patient education about the importance of routine tetanus vaccinations (boosters every 10 years) and proper wound care.

How to Approach the Question

First, identify the key clinical sign presented in the question: 'lock jaw'.
Recognize that 'lock jaw' is the common term for the medical sign 'trismus'.
Systematically review the options and recall the classic presentation of each disease.
Tetanus is famously associated with muscle rigidity and spasms, with trismus being a hallmark sign.
Eliminate the other options based on their primary symptoms: Tuberculosis (respiratory), Pertussis (paroxysmal cough), and Rabies (encephalitis, hydrophobia).
Select the option that directly and classically matches the key sign of lock jaw.

Concept Tested & Keywords

QXUsV0V8pNZcUiNeYjknDJ

E6 Medicine Davidson Principles Practice 24e p. 1146-1148

E6 Nelson Textbook of Pediatrics(2024) — Volume 1 p. 1826-1828

E6 Medicine Harrison 22e Part 1 p. 1271-1273

Practise the full DSSSB -28 August 2019 (Shift-2)

Attempt every question from this paper in a timed mock, then review the full solution for each one.