NORCET -7 Prelims: A newborn delivered by forceps exhibits an asymmetrical Moro reflex. This finding is indicative of injury to:

NORCET -7 Prelims

Child Health Nursing (Pediatrics)

Medium

Appeared in: NORCET -7 Prelims

Explanation

The Moro reflex is a normal neonatal startle response involving symmetrical abduction and extension of the arms.
An asymmetrical Moro reflex, where one arm's movement is absent or weak, is a classic sign of a unilateral injury affecting that limb.
Forceps delivery is a risk factor for birth trauma, including stretching or tearing of the brachial plexus nerves due to lateral traction on the head and neck.
Injury to the upper brachial plexus (C5-C6 nerve roots), known as Erb's palsy, results in paralysis of the shoulder and arm muscles, causing the Moro reflex to be absent on the affected side.

Option A: The femoral plexus innervates the muscles of the anterior thigh. An injury here would affect leg movement, not the arm movements involved in the Moro reflex.
Option B: The sacral plexus supplies nerves to the posterior thigh, lower leg, and foot. Injury would manifest as deficits in the lower extremities, which are not assessed by the Moro reflex.
Option C: The cervical plexus primarily innervates the neck muscles and gives rise to the phrenic nerve (C3, C4, C5), which controls the diaphragm. While phrenic nerve palsy can occur with brachial plexus injuries, the cervical plexus itself does not control arm movement for the Moro reflex.

Clinical Relevance

Nursing practice connection: Knowing Assessment of neonatal reflexes and identification of birth-related nerve injuries helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Nurses performing the initial newborn assessment are often the first to identify an asymmetrical Moro reflex. Prompt detection and reporting are crucial for early diagnosis and intervention.
Management of brachial plexus injury involves careful handling of the affected arm, physical therapy to maintain range of motion and prevent contractures, and parent education on proper care.
A fractured clavicle is a key differential diagnosis as it also presents with an asymmetrical Moro reflex due to pain on movement. The nurse should assess for crepitus (a crackling feeling) over the collarbone.

How to Approach the Question

First, identify the key clinical finding in the question stem: 'asymmetrical Moro reflex'.
Recall the normal Moro reflex, which involves symmetrical movement of both arms. Understand that 'asymmetrical' means one side is not functioning correctly.
Connect the function (arm movement) to the anatomy (nerves controlling the arm).
Analyze the options provided. Each option is a nerve plexus. Your task is to match the affected body part (the arm) with the correct plexus.
Eliminate the plexuses that do not control the arm: Femoral plexus (anterior leg), Sacral plexus (posterior leg/foot), and Cervical plexus (neck/diaphragm).
This process of elimination leaves the Brachial plexus, which is the correct network of nerves supplying the arm. The context of a 'forceps delivery' reinforces this, as it's a known risk factor for traction injuries to the brachial plexus.

Concept Tested & Keywords

Concept Tested: Assessment of neonatal reflexes and identification of birth-related nerve injuries.
Stem keywords: newborn, forceps, asymmetrical Moro reflex
Lead-in keywords: indicative of injury to
Clinical cues: Forceps delivery is a key clinical cue, as it is a risk factor for traction injuries during birth.
Negative lead-in flag: false

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E6 Nelson Textbook of Pediatrics(2024) — Volume 1 p. 1077-1079

E6 Obstetrics Williams p. 19-36