First described as a syndrome by Apert in 1906 Apert syndrome primarily affects the head, hands, and feet and is characterized by synostosis [fusion] of the cranial sutures and varying degrees of complex syndactyly of the hands and feet.
Apert syndrome is very rare, probably occurring in one in 200,000 births.
Etiology is not known. It is, a genetic disturbance with a strong dominant inheritance but sporadic cases due to mutation do occur.
Types of Apert Syndrome
Hand anomalies in Apert syndrome have following common features
- Abnormally shaped proximal phalanx [delta phalanx] leading to radial deviation of thumb
- Complex syndactyly of the index, long, and ring fingers
- Symphalangism of the central segments of the index, long, ring, and small fingers
- Simple syndactyly of the web space between the ring and small fingers.
The extent of syndactyly between thumb and index finger is the basis for the classification of Apert syndactyly into 3 types
Type I [Spade Hands]
Most common and the least severe. The thumb is foreshortened and associated with a radial deviation due to abnormal proximal phalanx or delta phalanx.
the thumb and index finger are separate, the first web space is shallow and there is a complex syndactyly of the index, long, and ring fingers. Simple syndactyly of the small and ring fingers is present.
These types of hands are called spade hands.
Type II [Mitten or Spoon Hands]
There is a simple incomplete or complete syndactyly of the thumb with the index ray, without any bony union. The hand has a large, concave palm. There is a more extensive bony union of the distal phalanges of the index, long, and ring fingers than in type I.
As in type I, there is a simple and complete syndactyly of ring finger–small finger. These have been referred to as mitten hands or spoon hands.
Type III [Rosebud or Hoof hands]
This type is the most severe form but least common.
A bony or cartilaginous union is present between all 5 fingers with all 5 nail plates are conjoined. The thumb cannot be distinguished from the index ray. The small finger, although joined by a common fingernail, does not have an osseous union and remains a simple but complete syndactyly but metacarpal synostosis of the small and ring finger rays may be present. Type III hands have been termed rosebud or hoof hands. Symphalangism is present between the proximal and middle phalanges, without the formation of a proximal interphalangeal (PIP) joint in the ring, long, and index fingers.
The head is peaked and vertically elongated in its anteroposterior diameter, with the planes of the face and the back of the skull being parallel.
The enlarging brain causes increased intracranial pressure.
Eyes are protuberant eyes and wide-spaced. There is a divergence of the transverse axis of eyes. Strabismus and progressive impairment of vision are common.
Often the posterior palate is high-arched, and there are fusion defects of the maxilla and mandible.
Convolutional atrophy of the brain and mental retardation are common.
The hand deformities are of variable severity, as described above.
Often both bones of the forearm are shortened, the elbows are stiff, and shoulder abduction is limited.
Treatment of Apert syndrome involves is a multidisciplinary neurosurgical and plastic surgical reconstruction. An osteotomy of the cranial bones is performed to prevent an increase in intracranial pressure, and the facial bones are reconstructed.
With surgical techniques which are available today, the rate of success is good.
At 6 to 12 months of age, the hands are treated for syndactyly. Liberation of adhering fingertips permits normal longitudinal growth of the fingers and prevents progressive deformation of the interphalangeal joints. The timing of the surgery is critical because the child requires multiple operations for other abnormalities of the cranium, midface, and orbits associated with Apert syndrome.
The skin coverage of the separated fingers is provided by local flaps and skin grafting; full-thickness skin grafts are better than split-thickness skin grafts.
The range of motion exercises are performed to increase the arcs of flexion of the proximal interphalangeal and distal interphalangeal joints. Long-term follow-up studies show marked improvement in function.