What is the medical term for a condition where one arm is shorter than the other due to a birth defect?

Hemimelia: The Medical Term for Congenital Limb Length Discrepancy

The medical term for a condition where one arm is shorter than the other due to a birth defect is hemimelia, which is classified as a limb deficiency disorder (LDD).

Types of Limb Deficiency Disorders

• Limb deficiencies are broadly classified into two main categories:

  • Transverse deficiencies: These involve absence of distal structures with intact proximal segments, with the axis of deficiency perpendicular to the extremity 1
  • Longitudinal deficiencies: These can be isolated or associated with certain syndromes and chromosomal anomalies 2

• Approximately 50% of all limb deficiencies are transverse, and 50% of those defects are digital, involving the absence of parts of one or more fingers or toes 1

Specific Terminology for Unilateral Limb Shortening

• Hemimelia: The specific term for congenital absence or shortening of one limb 3
• Hemihypertrophy: When one side of the body grows faster than the other, resulting in asymmetry 4
• Unilateral upper limb muscular hypertrophy: A condition involving abnormal muscles with hypertrophic appearance in one upper extremity 5

Causes of Congenital Limb Deficiencies

• Vascular disruption: Many isolated limb deficiencies are hypothesized to be caused by vascular disruption during embryonic limb formation or in already-formed fetal limbs 1, 3
• Timing-dependent severity: The timing of vascular disruption correlates with the severity of the defect:
  • Earlier disruptions (before 68 days' gestation) tend to cause more severe and proximal defects 3
  • Later disruptions (after 70 days' gestation) typically result in more limited digital deficiencies 3
• Iatrogenic causes: Procedures such as chorionic villus sampling (CVS) have been associated with limb deficiencies when performed at certain gestational ages 1, 3

Associated Conditions

• Limb deficiencies may occur as isolated defects or as part of syndromes and associations:
  • VACTERL association: Includes vertebral abnormalities, anal atresia, cardiac abnormalities, tracheo-esophageal fistula, renal abnormalities, and limb abnormalities 1, 6
  • Oro-mandibular-limb hypogenesis: A rare combination of transverse limb deficiencies with absence or hypoplasia of the tongue and lower jaw 1, 6
  • Ectrodactyly-ectodermal dysplasia-clefting syndrome: Associated with central axis defects 6

Diagnosis

• Physical examination should compare both limbs to identify asymmetry 7
• No significant differences are normally found between right and left extremities for arm and forearm length and circumference measurements 7
• Contralateral limbs can be used for comparison of length and circumference in cases of unilateral upper extremity abnormality 7
• Consultation with a medical geneticist is advisable to determine if the limb deficiency is isolated or part of a syndrome 2

Management Considerations

• Long-term care should occur in a specialized limb deficiency center with expertise in orthopedics, prosthetics, and occupational and physical therapy 2
• Emotional support and contact with other families with similar conditions is important 2
• With appropriate care, most children with limb deficiency disorders can lead productive lives 2