Midface Hypoplasia
Midface (maxillary) hypoplasia refers to underdevelopment of the central facial skeleton, primarily the maxilla (upper jaw and cheekbones) and often the nasal bridge. This presents clinically as a flat midface with a depressed nasal bridge, malar flattening, shallow orbits (making the eyes appear prominent), and a relative prognathism of the mandible. Dental malocclusion (often Class III) is common due to the retruded maxilla.
Associated Syndromes/Conditions
Achondroplasia
A skeletal dysplasia caused by FGFR3 mutation.
Facial: Frontal bossing, midface retrusion, depressed nasal bridge.
MSK/Neurologic: Disproportionate short stature, lumbar lordosis, joint laxity, spinal canal stenosis (especially lumbar), and foramen magnum stenosis which can compress the cord/brainstem. Chronic back and radicular leg pain are common in adulthood. Narrow nasal passages and Eustachian tubes lead to otitis media, conductive hearing loss, and increased risk of OSA (causing fatigue and headaches).
Relevance: Recognition of midfacial flattening can guide early diagnosis and anticipation of spinal issues. Any signs of cord compression in infancy warrant neurosurgical evaluation. Persistent pain in older patients should prompt imaging for stenosis. Diagnosis is clinical at birth and confirmed via radiographs and genetic testing.
Apert and Crouzon Syndromes
FGFR2-related craniosynostosis syndromes.
Facial: Midface hypoplasia, beaked nose, exorbitism due to shallow orbits. Apert has complex syndactyly; Crouzon has normal hands.
MSK/Neurologic: Can cause raised ICP needing cranial expansion surgery. Apert may have vertebral fusions and scoliosis. Multiple surgeries may cause residual pain.
Relevance: Midface retrusion causes airway obstruction—many require CPAP or tracheostomy. Postoperative headache relief is common after midface advancement. Risk of corneal exposure and potential trigeminal compression during craniofacial growth or surgery.
Diagnostic: Clinical features and genetic testing of FGFR2 confirm diagnosis.
Down Syndrome (Trisomy 21)
Facial: Midface hypoplasia, flat nasal bridge, epicanthic folds, upslanting palpebral fissures, small mouth.
MSK/Neurologic: Generalized hypotonia, ligamentous laxity, atlantoaxial instability, hip dysplasia, patellar instability, and early degenerative joint disease.
Relevance: Facial features prompt diagnosis, allowing precautions for C1-C2 instability (e.g. during sports or anesthesia). OSA and ENT issues from midface structure. Delayed milestones and musculoskeletal aches possible.
Mucopolysaccharidoses (MPS)
Facial: Coarse facies with midface flattening from glycosaminoglycan deposition.
MSK/Neurologic: Joint contractures, spine compression, stiff joints, and compressive neuropathies.
Relevance: ENT problems (OSA, sinus issues) due to facial structure; severe skeletal disease causes significant pain.
Fetal Alcohol Spectrum Disorder (FASD)
Facial: Smooth philtrum, thin upper lip, short palpebral fissures, and midface hypoplasia.
MSK/Neurologic: Hypotonia, fine motor issues, developmental delay. Pain syndromes are not classic.
Relevance: Early diagnosis aids developmental support. Facial clues help with timely intervention.
Other Conditions
Cleidocranial Dysplasia: Midface hypoplasia, broad forehead, dental crowding, skeletal abnormalities (absent clavicles), but generally not painful.
Williams Syndrome: Broad forehead, low nasal bridge, joint laxity, early stiffness, hypercalcemia (can cause abdominal pain).
Congenital Hypothyroidism: Myxedematous facies due to soft tissue swelling, not true bony hypoplasia.
Why it Matters
Midface hypoplasia contributes to airway problems like OSA, impacting sleep and cardiovascular health. It also affects dental development, requiring orthodontics. While the hypoplasia itself isn't painful, associated complications (e.g. otitis media, headaches from OSA, skeletal pain from achondroplasia or MPS) make its recognition clinically valuable. Early identification enables multidisciplinary care planning (e.g. ENT, orthodontics, neurosurgery).
Diagnostic Note
Assessment includes visual inspection and cephalometric imaging (e.g. lateral cephalogram). CT imaging shows underdeveloped midface bones in syndromic cases. Sleep studies are indicated if apnea is suspected. In achondroplasia, neuroimaging of the foramen magnum is essential. Orthodontic and ENT evaluations are routine.
