MORQUIO SYNDROME-
Morquio syndrome is a member of a group of inherited metabolic disorders collectively termed mucopolysaccharidoses (MPSs).
The MPSs are caused by a deficiency of lysosomal enzymes required for the degradation of mucopolysaccharides or glycosaminoglycans (GAGs).
Currently, 11 distinct single lysosomal enzyme deficiencies are known to cause 7 recognized phenotypes of MPS.
All the MPSs are inherited in an autosomal recessive fashion except Hunter syndrome (MPS type II), which is X-linked..
CLINICAL FEATURES –
The patient with Morquio syndrome is usually evaluated during the second or third year of life for unusual skeletal features. These include short trunk dwarfism, pectus carinatum, kyphosis, gibbus, scoliosis, genu valgus, flaring of the lower ribs, and joint abnormalities (joints range from hypermobile to contracted).
- At the time of initial evaluation, families commonly report a history of increased clumsiness and falling.
- Because no mental deficiencies or loss of developmental milestones occurs, this is not a presenting symptom. In fact, this is one important characteristic that distinguishes Morquio syndrome from many of the other mucopolysaccharidoses (MPSs).
- Because the MPSs are progressive disorders, the patient becomes more severely affected over time. As lysosomal accumulation of KS continues, mild coarsening of facial features, corneal clouding, and hepatomegaly become apparent.
- Other less frequent findings in Morquio syndrome include hearing difficulties, hernias, and thin tooth enamel with a predisposition to caries.
- A characteristic of all patients with Morquio syndrome is odontoid hypoplasia. In combination with ligamentous laxity and extradural mucopolysaccharide deposition, this results in atlantoaxial subluxation, with consequential quadriparesis or even death.
- A history of exercise intolerance in patients with Morquio syndrome often predicts the presence of occult cervical myelopathy, which can also cause bowel and bladder dysfunction.
Imaging Studies:
- A full skeletal survey should be obtained in a patient thought to have MPS. For Morquio syndrome, the authors recommend the following radiographic studies:
- Anteroposterior (AP) and lateral views of the skull with visualization of the sella
- Flexion and extension radiographs of the cervical spine
- AP and lateral views of the odontoid
- AP and lateral views of the chest
- Standing AP and lateral views of entire spine
- Standing pelvis view with visualization of the femoral heads articulating with the acetabulum
- Preferably standing AP views of the lower extremities, including the entire femur, articulation with tibia (knees for genu valgus), and ankles
- AP views of at least one foot, one hand, forearm, elbow in extension, humerus, and shoulder.
X RAY FEATURES –
1) UNIVERSAL VERTEBRA PLANA-
a) Superior and inferior surfaces of DL vertebra are irregular and appear to be approximate as central anterior beak.
b) Vertebral body is flatten in morquio syndrome but normal height in HURLER syndrome.
c) Vertebral beak is inferior in HURLER syndrome.
d) Vertebral beak is central in morquio syndrome.
2) Odontoid hypoplasia and ligamentous hyper laxity can result in atlanto axial sublaxation and cord compression superiorly.