What is the clinical significance of Beevor's sign?

Beevor's Sign: Clinical Significance and Diagnostic Value

Beevor's sign is highly specific for facioscapulohumeral muscular dystrophy (FSHD) and spinal cord lesions between T10-T12, making it a valuable clinical examination finding that should be routinely assessed in patients with suspected neuromuscular disorders or spinal cord injuries.

Definition and Mechanism

Beevor's sign refers to the upward movement of the umbilicus when a supine patient flexes their neck or attempts to sit up. This sign was first described by British neurologist Charles Edward Beevor (1854-1908) 1. The phenomenon occurs due to:

• Paralysis or weakness of the inferior portion of the rectus abdominis muscle
• Preserved function of the upper rectus abdominis fibers
• Resulting imbalance causing the umbilicus to move upward during truncal flexion

Clinical Significance

1. Diagnostic Value in FSHD

Beevor's sign has significant diagnostic value in FSHD:

• Present in approximately 90% of patients with FSHD 2
• Sensitivity varies based on phenotype:
  • Present in 11/13 (85%) patients with typical FSHD phenotype 3
  • Present in only 4/15 (27%) patients with atypical FSHD phenotype 3
• High specificity: absent in most patients with other neuromuscular disorders 2

2. Indicator of Spinal Cord Pathology

Beevor's sign can indicate a lesion of the spinal cord between segments T10 and T12 or its nerve roots 4, 5. This makes it valuable for:

• Localizing spinal cord injuries
• Providing confirmatory information about neurological level and type of spinal cord lesion
• Detecting subtle neurological deficits that might otherwise be missed

Clinical Assessment

To properly assess for Beevor's sign:

1. Position the patient supine on the examination table
2. Expose the abdomen to visualize the umbilicus
3. Ask the patient to flex their neck or attempt to sit up without using their arms
4. Observe for upward movement of the umbilicus

Differential Diagnosis

When Beevor's sign is positive, consider:

1. FSHD - particularly in patients with facial weakness, scapular winging, and proximal upper extremity weakness
2. Spinal cord lesions (T10-T12) - may be accompanied by other signs of spinal cord dysfunction
3. Other rare neuromuscular disorders - though much less common

Clinical Implications

The presence of Beevor's sign should prompt:

1. For suspected FSHD: Genetic testing for confirmation, particularly looking for D4Z4 repeat contractions on chromosome 4q35
2. For suspected spinal cord pathology: MRI imaging of the thoracic spine to evaluate for lesions between T10-T12
3. Further neuromuscular assessment: Including electromyography and nerve conduction studies to characterize the pattern of muscle involvement

Practical Value

Beevor's sign is particularly valuable because:

• It's a simple bedside test requiring no special equipment
• It can be detected before functional weakness of abdominal wall muscles becomes apparent 2
• It helps distinguish FSHD from other forms of facioscapulohumeral syndrome
• It provides localizing information in spinal cord injuries 5

Conclusion

Beevor's sign is an underutilized but valuable clinical examination finding that can provide important diagnostic clues, particularly for FSHD and thoracic spinal cord lesions. Its high specificity for FSHD makes it a useful screening test in the evaluation of patients with suspected neuromuscular disorders.