Apert Syndrome (Pediatric)

Synonyms
Acrocephalosyndactyly

INTRODUCTION

Definition

A branchial arch syndrome with a complex osseous-syndactyly (severe type of fused digits).

Epidemiology

  • Incidence is 1/80,000 live births.
  • More common in boys (M:F=1.5:1).

Etiology

Most new cases are sporadic but can be autosomal dominant due to mutation in FGFr2 gene with aberrancy of the fibroblast growth factor receptor-2 (FGF-2).
  • Leads to premature fusion of growth plates and suppressing of the selective apoptosis needed for separation of the digits.

Classification

Upton Classification: Guides decision-making.
  • Type 1 (spade hand):
    • Radial deviation of a small thumb with a shallow first web.
    • The index, long, and ring fingers display complete or complex syndactyly.
    • The little finger is attached by a simple complete or incomplete syndactyly.
    • Treated with separation and contouring of the tips of the digits.
    • Partial digit ablation may be required.
  • Type 2 (mitten or spoon hand):
    • The thumb is radially deviated and has an incomplete or complete simple syndactyly with the index.
    • The index, long, and ring fingers are distally fused, creating a curve in the palm with divergent metacarpals.
    • The little finger is attached to the ring with a mostly complete but simple syndactyly.
    • Treated with separation of tips of digits and deepening of web space.
  • Type 3 (rosebud hand):
    • The thumb, index, long, and ring are distally fused either cartilaginous or bony attachments.
    • The thumb can be very difficult to identify separately from the index.
    • The little finger is united to the ring by simple complete syndactyly. The nails can be confluent.
    • Proximal synostosis at the base of the fourth to fifth metacarpal can be present, as well as carpal fusions.
    • The border digits are reconstructed first.

CLINICAL FEATURES

Characteristics

  • Bilateral complex syndactyly of hands and feet.
    • Acrosyndactyly: So-called spadelike hand. Fusion of the digits occurs distally, with proximal fenestrations.
  • Craniosynostosis (premature closure of cranial sutures): There is a high, flattened and broad forehead, occipital flattening, and bulging.
  • Symphalangism: Ankylosis/fusion of interphalangeal joints.
  • Often radial clinodactyly of the thumb (curvature of a digit).
  • Radioulnar synostosis.
  • Glenoid hypoplasia.
  • Decreased mental capabilities/mental retardation with impairment in language development and motor skills. 
  • Low-set eye, decreased eyesight and strabismus.
  • Hyperhidrosis.
  • Decreased hearing

Signs

  • The patient has a dysmorphic face
  • Rosebud hands (complex syndactyly where the index, middle, and ring finger share a common nail).

DIAGNOSIS

Conventional Radiography

Will show complex syndactyly.

TREATMENT

Overview

Treatment goals: Create a more useful extremity with the ability to grip or perform pincer grasp in as few operations as possible with staged reconstruction.
  • Separation of digits, including the thumb.
  • Correction of thumb function.
  • Mobilization of the little finger.

Operative Treatment

Surgical release of border digits: Often the first step in surgical treatment. Done at 1 year of life. Digits-thumb and small finger are released first.
  • First stage: Deepening or creation of the 1st web space with a a 4-5 limb Z-plasty or dorsal skin graft. 
  • Second stage: Creation of the 4th web space followed by separation of the remaining digits.
Digital reconstruction:
  • Performed when the patient is 1.5-2 years of age.
  • The middle 3 digits are turned into 2 digits.
Separation of proximal metacarpal synostosis:
  • The synostosis should be separated early to improve mobility of the fifth ray.

PROGNOSIS AND COMPLICATIONS

Prognosis

  • The spectrum can be from normal to moderately disabled cognitive function.
  • Hand function and prognosis is best with the combination of thumb and little finger separation. This allows a tripod pinch and thumb based grip.
  • Movement of the fingers is typically isolated to the metacarpal phalangeal joints.

Complications

  • The need for revision surgery of web space contracture varies among authors from 3-18%.
  • Aberrant growth plates can cause clinodactyly after separation and osteotomies may be needed later on.
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References