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Odontoid C2 Fracture

KEY FACTS Terminology Type I: Avulsion fracture from tip of odontoid at insertion of alar ligament Usually stable injury Usually seen in conjunction with more extensive craniocervical injury Type II: Transverse fracture through base of odontoid Most likely to progress to nonunion without surgical fusion Type III: Oblique fracture extending from base of odontoid into body of C2 Imaging Direct visualization of fracture line on radiography…

Atlantoaxial Rotatory Fixation

KEY FACTS Imaging Abnormal rotatory motion of C1 with respect to C2 defined by 3-position CT scan Top Differential Diagnoses Etiologies of atlantoaxial rotatory fixation (AARF) Trauma Nasopharyngeal infection (Grisel syndrome) Prior head and neck surgery Pathology Pang type I AARF : Unaltered or locked C1-C2 coupled configuration regardless of corrective counter-rotation Pang type II AARF : Reduced C1-C2 separation angle with forced correction but C1…

Jefferson C1 Fracture

KEY FACTS Terminology Fracture(s) of C1 ring Imaging Multiple fractures of C1 arch (2-, 3-, and 4-part fractures) Combined offset of lateral masses of C1 relative to lateral margins of C2 ≥ 7 mm suggests interruption of transverse ligament Avulsion fragment off inner C1 pillar at insertion of transverse ligament indicates unstable fracture Widening of atlantoaxial interval ≥ 4 mm concerning for interruption of transverse ligament…

Atlantooccipital Dislocation

KEY FACTS Terminology Disruption of stabilizing ligaments between occiput and C1 Imaging Widened prevertebral soft tissues (nonspecific) Condylar sum > 4.2 mm has 100% sensitivity, 69% specificity, and 76% accuracy Increased basion-dens interval (BDI) distance > 8.5 mm (CT in adults) Widened unilateral atlantooccipital interval > 2 mm Widened, fluid-filled facet joints between condyles and C1 STIR/T2WI MR best show ligamentous injury Top Differential Diagnoses Occipital…

Fracture Classification

Craniocervical Junction Occipital condyle fractures are classified into 3 types. Type I = comminuted fractures due to axial loading; stable if contralateral side is intact Type II = occipital condyle fracture with skull base fractures; most of these are stable Type III = avulsion fracture due to tensile force on alar ligaments; may show occipitocervical instability Recent data (Maserati 2009) suggests that initial evaluation should be…

Kyphosis

KEY FACTS Terminology Accentuated thoracic ± reduced normal cervical, lumbar lordotic spinal curvature Normal 20-40°, hyperkyphotic if > 40° Curvature secondary to vertebral anomalies, degenerative spine disease, or idiopathic causes Imaging Accentuated dorsal thoracic curvature on lateral image Look for vertebral anomalies in patient with scoliosis or kyphosis Common in thoracic spine but can occur at any spinal level Top Differential Diagnoses Scheuermann kyphosis Wedging of…

Scoliosis

KEY FACTS Terminology General term for any lateral curvature of spine (≥ 10°) Imaging Lateral curvature of spine Returns to midline at ends of curve Rotational component common Most commonly thoracic or thoracolumbar Imaging approach Radiography for initial diagnosis Multiplanar MR to screen for bone, cord abnormalities CT for surgical planning, complications Top Differential Diagnoses Idiopathic scoliosis Neuromuscular scoliosis Congenital scoliosis Scoliosis due to congenital syndromes…

Introduction to Scoliosis

Terminology Scoliosis is considered to be present when there is a coronal plane curvature of the spine measuring at least 10°. However, treatment is not generally instituted unless the curvature is > 20-25°. The curvature may be balanced (returning to midline) or unbalanced. The vertebrae at the ends of the curve are designated the terminal (or end) vertebrae, whereas the apical vertebra is at the curve…

Spondyloepiphyseal Dysplasia

KEY FACTS Terminology Spondyloepiphyseal dysplasia (SED) Group of generalized skeletal dysplasias primarily involving vertebrae, proximal epiphyseal centers Affected patients demonstrate short trunk, neck, and limbs with normal hand and foot size Imaging Platyspondyly, vertebral hypoplasia & underossification, abnormal epiphyses ± pannus at C1/C2, os odontoideum Delayed ossification of capital femoral epiphysis → femoral head flattening, premature osteoarthritis Top Differential Diagnoses Spondylometaphyseal dysplasia Spondyloepimetaphyseal dysplasia Multiple epiphyseal…

Osteogenesis Imperfecta

KEY FACTS Terminology Genetic disorder of type I collagen resulting in bone fragility Classified into 4 types based on clinical, genetic, and radiographic criteria You’re Reading a Preview Become a Clinical Tree membership for Full access and enjoy Unlimited articles Become membership If you are a member. Log in here

Mucopolysaccharidoses

KEY FACTS Terminology Mucopolysaccharidoses (MPS) are inherited lysosomal storage disorders MPS I: Hurler; MPS II: Hunter; MPS III: Sanfillipo; MPS IV: Morquio You’re Reading a Preview Become a Clinical Tree membership for Full access and enjoy Unlimited articles Become membership If you are a member. Log in here

Neurofibromatosis Type 2

KEY FACTS Terminology Rare autosomal dominant disease from chromosomal 22 defect in which all patients develop CNS tumors Mnemonic for NF2 tumors: M ultiple i nherited s chwannomas, m eningiomas, and e pendymomas (MISME) Top Differential Diagnoses Metastases Hemangioblastomas Nonsyndromic schwannoma Nonsyndromic meningioma Nonsyndromic ependymoma Lymphoma Pathology 22q12 deletion correlates with loss of NF2 gene product “merlin” (a.k.a. schwannomin) Definite diagnosis of NF2 Bilateral CNVIII (vestibular)…