Very interesting "snake eye" sign, have you seen it?

"snake-eye appearance" (SEA) refers to the high signal of bilateral anterior angle symmetry of the spinal cord on transverse MRI, resulting from
degeneration of anterior horn cells of the spinal cord.

Amyotrophic lateral sclerosis, cervical spondylosis amyotrophy, and patients with Pingshan disease often present with such signs
.

Amyotrophic lateral sclerosis (ALS) is a progressive, malignant and widespread degeneration of motor neurons
.
Clinical features include spasms of the extremities, focal or multiple limb muscle atrophy, fatigue, dysphonia, dysphagia, and chewing difficulties
.

MRI of the cervical spine shows T2 hyperintensity extending longitudinally from the anterior spinal cord of C4-8 (left).

T2-axis images show bilateral anterior horn cell hyperintensity, with a characteristic owl or snake eye appearance (upper right and lower right).

This case was eventually confirmed as amyotrophic lateral sclerosis
.

Amyotrophic cervical spondylosis (also known as muscular atrophic cervical spondylosis, cervical spondylotic amyotrophy) is based on the compression of the anterior horn cells of the spinal cord caused by degenerative factors, with deltoid muscle, shoulder girdle muscle, especially hand interosseous muscle muscle atrophy as the main clinical manifestations, causing a special type of cervical spondylosis with weakened upper limb muscle strength, not accompanied by or slightly accompanied by radiculopathy or myelopathy caused by upper limb radicular pain and
。 There are proximal and distal types
.
The proximal type is characterized by weakness and muscle atrophy of the deltoid and biceps innervated by C5 and C6 nerve roots; The distal form presents with muscle weakness and muscle atrophy
below the C7 nerve root, innervating the internal hand, extensor and flexor muscles.

A: MRI sagittal T2-weighted image showing C3/4 (arrow) horizontal spinal cord hyperintensity
.
B, C: Transsection suggests "snake eye" changes in the anterior horn of the spinal cord at levels C3-C4 (arrows
).
This case was eventually confirmed as amyotrophic cervical spondylosis
.

Hirayama disease (also known as juvenile muscular atrophy of the distal upper extremity) is a benign self-limited motor neuron disease with insidious onset and tends to occur in adolescents, with a peak incidence of 15-25 years of age, and more common in
men.
Mainly manifested by asymmetric weakness and atrophy of the distal upper limb muscles.
The brachioradial muscles are mostly unaffected and have "slope-like" changes
.
Most patients have chill tremors
.
There are no paresthesias and pyramidal signs
.

Illustration: Left: C7, C8 and T1 bilateral involvement of hand and forearm atrophy; Right: MRI transection T2-weighted image showing "snake eye" sign hyperintensity at
C5-7 levels.
This case was eventually confirmed to be Hirayama disease
.

This sign often indicates a poor prognosis of upper limb motor function, and should be fully explained
to the patient before surgery.