History and Physical Examination
In evaluating a patient, several aspects of his or her medical history should be investigated for coordination of care. Respiratory difficulties, neurogenic problems, family history, and history of any prior skeletal surgery should be investigated.
The diagnosis can be made at birth with the observation of pathognomic features or within the first few months of life, when the cystic swelling of the ears becomes apparent. [12] Neonates with diastrophic dysplasia may be thought to have atypical achondroplasia at birth, but the diagnosis is relatively easy to establish in the older child or adult because of the unique combination of deformities. Birth length, head circumference, and weight should be recorded. The mental status and intelligence findings are normal.
Height is related to severity of involvement; taller people are less severely affected than shorter people. The mean height is 136 cm in men and 129 cm in women. The pubertal growth spurt is diminished; therefore, the overall growth failure is progressive. The other components of puberty occur normally. This fact suggests that the bones do not respond to hormonal influences.
The patient's height percentile for age should be determined by using specific growth charts. In relation to trunk length, the limbs are shorter than normal. Short-limbed stature can be confirmed by measurement of the upper-to-lower segment ratio. The normal ratio is 1.6 at birth and decreases to 0.93 during adolescence. Kyphoscoliosis and hip and knee contractures further accentuate the apparent dwarfism. Difficulty in walking is common, and some patients are wheelchair-bound. [13, 14, 15]
The expression and severity of diastrophic dysplasia vary greatly. Patients may present with complaints pertaining to the head and neck, spine, major joints, and hands and feet (see the image below).
Child with diastrophic dysplasia. Note micromelic dwarfing with hitchhiker thumb, flexion contractures of the knee, and clubfeet.
Head and neck
Typical facial features are present in most patients. [16] Prominent cheek and circumoral fullness inspired the historical term cherub dwarf. The nasal bridge is narrow, without flattening or depression. Because the eyes are normally spaced, the distance between the bridge of the nose and the inner canthus of the eye appears to be increased. In contrast to the bridge, the mid-nose is broad. The nostrils flare, and the columella dips low between them.
The arch of the palate is wide, and many teeth are visible when the patient smiles. The face has a long, full appearance with a high, broad forehead and square jaw. Midline hemangiomas are sometimes present but fade with age.
Approximately 50% of patients have a cleft palate, either complete or partial. Other abnormalities, such as a high and arched palate, bifid uvula, or submucous clefts, are common. This cleft palate may also contribute to aspiration pneumonia. The cartilage of the larynx and trachea is abnormally soft, and this may contribute to narrowing of respiratory passages.
The abnormal palate may play a part in the production of the somewhat characteristic voice heard in patients with this condition. Patients also have a hoarse cry. Hyponasality or misarticulation of R, S, or L sounds is observed in 50% of these patients, possibly due to defects in the palate or vocal cords or due to laryngeal cartilage affection in a process similar to that seen in the ears. [17]
The pinnae, though unaffected at birth, develop acute swelling, usually bilateral, at 3-6 weeks of age (see the image below). They are reddened, swollen, hot, and often fluctuant and may feel cystic. After these findings resolve, the cartilage thickens and deforms, giving rise to cauliflower ear, a pathognomonic feature of diastrophic dysplasia. This cauliflower ear is present in 85% of patients. Eventually, the pinnae may become calcified or even ossified. Typically, older patients have rock-hard masses in the superior portions, which are easily palpable.
Pinnal calcification may also be present in other conditions, such as Addison disease, ochronosis, acromegaly, hypertension, diabetes mellitus, and hyperthyroidism. Abnormal hearing has been reported in patients with diastrophic dysplasia, as well as in patients with other skeletal dysplasias. [18] Although deafness is rare, it may be present as a consequence of external auditory canal stenosis or fusion of the ossicles.
Spine
One half to one third of patients develop cervical kyphosis. Cervical kyphosis may be present in infancy; its course is variable. Though spontaneous resolution has been reported, the possibility of progression with neurologic involvement should always be considered. Progressive kyphosis of the cervical spine causing quadriplegia with respiratory muscle paralysis and neurogenic bladder has been described in young children. [19, 20, 21, 22, 23, 24]
Generally, external signs of cervical abnormalities are absent; however, 80% of patients present with some degree of spinal curvature. Scoliosis is not present at birth, but it tends to develop within the first year of life; it becomes progressively severe with weightbearing.
Spinal stenosis is not common, in contrast to its presence in achondroplasia. Mild stenosis may be masked by a patient's relative inactivity. Most patients have significant lumbar lordosis, most likely due to associated hip flexion contracture. Kyphoscoliosis can cause imbalance of the trunk, leading to difficulties in gait and a reduction in already short standing height.
Early and rapid progression of spinal degenerative changes is a normal finding in patients, regardless of age, and leads to stiffness of the cervical spine on physical examination. One case of atlantoaxial instability has been reported, to the authors' knowledge.
Scoliosis is common, with a reported prevalence of 37-88%. It can be divided into the following three subtypes:
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Early progressive
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Idiopathic
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Mild nonprogressive (see the image below)
Scoliosis in a patient with diastrophic dysplasia. The curve is a mild, nonprogressive-type curve. Note the degenerative changes associated with the scoliosis.
In early progressive scoliosis, dysplastic curves are sharply angular and segment curves are short with associated kyphosis at the same level. Neurologic deficits may be present from severe kyphosis.
Lumbar lordosis is usually significant (see the image below). Spinal stenosis is less common. Degenerative changes are common at all levels, and in patients of all ages. These changes lead to spinal stiffness that is evident on clinical examination.
Lumbar lordosis in a patient with diastrophic dysplasia. Note the horizontal sacrum and mild degenerative changes in the lumbar spine.
Major joints
The hips maintain a persistent flexion contracture. Patients may present with hip subluxation. Arthritic changes develop by early-to-middle adulthood. Hip dysplasia is usually progressive and may result in a significant decrease in range of motion. [25, 26]
The knees, too, have flexion contractures. Excessive valgus with lateral dislocation of the patella may occur. Genu valgum with patellar dislocation may occur in patients with diastrophic dysplasia. Genu varum is uncommon. Similar to hip changes, arthritic changes develop by early-to-middle adulthood.
Rarely, the patient may manifest joint laxity and instability rather than limitation of motion. The symptoms may involve hips, knees, ankles, shoulders, or elbows. [27]
In the major joints, motion is markedly limited, and there is a tendency toward dislocation or subluxation. The hips, knees, and elbows are usually affected. At birth, the hips are normal, but with walking, coxa vara becomes apparent, often with subluxation or dislocation of the femoral heads. Bilateral hip dislocations occur in 25% of patients. The proximal femoral epiphyses deform. Hinge abduction may develop in some patients.
Valgus may develop at the knee joint, along with subluxation of the patella and flexion contracture. The elbows and shoulders are occasionally subluxated, and the radial head may be dislocated. Degenerative joint disease of the hips and knees develops in early-to-mid adulthood. The joints may be affected by webbing, in addition to the contractures.
Hands and feet
The hands are short, broad, and ulnarly deviated due to shortening of the ulna. The fingers appear widely spaced. About 95% of patients have an abducted, hypermobile, hitchhiker thumb (see the image below). The first metacarpal is characteristically short, leading to the clinical appearance of proximal insertion of the thumb. Flexion is absent at multiple proximal interphalangeal (PIP) joints of the fingers. This finding, termed symphalangism, is associated with the absence of normal flexural creases and suggests an antenatal onset.
Characteristic abducted position of the thumb in a patient with diastrophic dysplasia.
Foot deformities are stiff and involve bony malformations, contracture, and malalignment, and they are difficult to correct passively. A wide spectrum of deformities exist, some of which are specific for the condition. Deformities may range from equinovarus to pure equinus or valgus. In a large series of 102 patients, the various deformities included tarsal valgus deformity with metatarsus adductus (43%), equinovarus adductus (29%), metatarsus adductus (13%), and pure equinus (8%).
The great toe may be in additional varus, analogous to hitchhiker thumb. A frequent finding is a wide gap between the great toe and the second toe. Clubfoot, the expression generally used for the foot deformity, is a misnomer. [28, 29]
Other findings
Associated hernia is another possible manifestation of the basic mesodermal defect. Cases of inguinal hernia have been reported in patients with diastrophic dysplasia.
Complications
Morbidity occurs due to the following associated conditions:
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Cleft palate
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Respiratory insufficiency due to laryngotracheobronchomalacia
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Progressive deformities and contractures of joints
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Progressive hip dysplasia and dislocation
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Severe foot deformities [30]
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Severe hand deformities
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Progressive spinal deformities (scoliosis, kyphosis, lordosis)
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Cervical kyphosis with neurologic involvement
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Early degenerative changes in joints
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Child with diastrophic dysplasia. Note micromelic dwarfing with hitchhiker thumb, flexion contractures of the knee, and clubfeet.
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Ear deformity in a patient with diastrophic dysplasia.
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Characteristic abducted position of the thumb in a patient with diastrophic dysplasia.
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Scoliosis in a patient with diastrophic dysplasia. The curve is a mild, nonprogressive-type curve. Note the degenerative changes associated with the scoliosis.
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Lumbar lordosis in a patient with diastrophic dysplasia. Note the horizontal sacrum and mild degenerative changes in the lumbar spine.
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Radiograph of the cervical spine obtained with the neck in neutral alignment shows severe kyphosis between C2 and C6 in a patient with diastrophic dysplasia.
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Early progressive type of scoliosis in a patient with diastrophic dysplasia. These curves typically have short segments and are sharply curved; they may have associated dysplastic changes in the vertebrae.
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The humerus in a patient with diastrophic dysplasia. Typically, all of the long bones are short and thick. Note the epiphyseal flattening and irregularity of the proximal humeral epiphysis. Metaphyseal flaring of the distal humerus is present.
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Pelvis with both hips in an adult with diastrophic dysplasia. Note the dysplastic shape of the femoral head, along with characteristic degenerative changes.
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Pelvis and both hips in a patient with diastrophic dysplasia. Note the short and broad neck of the femur. The appearance of the femoral epiphyses is delayed. Flattening of the epiphyses is present.
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Image in a patient with diastrophic dysplasia. The acetabulum is shallow and shows a double-hump configuration on the right side. Both the femoral heads are severely dysplastic.
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Image in a patient with diastrophic dysplasia. The patella is subluxed laterally, with mild hypoplasia of the lateral femoral condyle.
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Image in a patient with diastrophic dysplasia. The tubular bones of the hand are short and broad. The first metacarpal is particularly shortened. The ulna is shorter, and the radius shows flaring at its distal end.
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Image in a patient with diastrophic dysplasia. Oblique view of the hand shows a short first ray with marked abduction.
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Image in a patient with diastrophic dysplasia. Radiograph of the hands shows abducted and short first metatarsal, along with affection of the proximal interphalangeal (PIP) joint of all fingers. Ankylosis of the fifth PIP joint is present. The middle phalanges appear extremely short.
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Image in a patient with diastrophic dysplasia. The metatarsus adductus with medial twisting of metatarsals is evident. The first metatarsal is shortened. Also note the lateral subluxation of the navicular over the talus that gives the appearance of a skew foot.
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Deformity of the foot in a patient with diastrophic dysplasia.
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Severe equinus deformity in a patient with diastrophic dysplasia.
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Image in a patient with diastrophic dysplasia. CT scan, A 3-dimensional reconstruction, shows bilateral dysplasia and dislocation of hips.
