**Question:** Goose neck deformity is seen in

A. Duchenne muscular dystrophy
B. Spinal muscular atrophy
C. Myotonic dystrophy
D. SMA (Spinal muscular atrophy)

**Correct Answer:** D. SMA (Spinal muscular atrophy)

**Core Concept:**
Goose neck deformity is a clinical sign characterized by neck stiffness and inability to extend the neck due to proximal muscle weakness. This is commonly seen in neuromuscular disorders affecting anterior horn cells in the spinal cord.

**Why the Correct Answer is Right:**
Goose neck deformity is primarily seen in SMA (Spinal muscular atrophy) because it is a neuromuscular disorder characterized by degeneration of motor neurons in the spinal cord. The weakness of neck extensors leads to the neck stiffness and inability to extend the neck, resulting in the goose neck appearance.

**Why Each Wrong Option is Incorrect:**
A. Duchenne muscular dystrophy (DMD) is a X-linked recessive genetic disorder primarily affecting skeletal muscles. Goose neck deformity is not a common feature in DMD.
B. Spinal muscular atrophy (SMA) and Duchenne muscular dystrophy (DMD) are distinct disorders with different pathophysiology. Goose neck deformity is not a feature of spinal muscular atrophy.
C. Myotonic dystrophy is a myopathic disorder characterized by myotonia and myotonic discharges on electromyography (EMG), not goose neck deformity.
D. Spinal muscular atrophy (SMA) is the correct answer due to the involvement of anterior horn cells in the spinal cord leading to neck extensor weakness and the associated goose neck deformity.

**Clinical Pearl:**
Understanding the clinical signs and symptoms is crucial for differential diagnosis in medical practice. While goose neck deformity may resemble a symptom in various neurological disorders, it is primarily associated with spinal muscular atrophy (SMA) due to the involvement of anterior horn cells in the spinal cord. This helps healthcare professionals to narrow down the differential diagnosis and guide appropriate investigations and treatment options.