![Etiology
• Chiari malformations (descent of the cerebellar tonsils or vermis
into the cervical spinal canal, sometimes associated with platybasia)
• General or systemic disorders that affect skeletal growth and
development and involve the craniocervical junction include the
following:
• Achondroplasia (impaired epiphyseal bone growth, resulting in
shortened, malformed bones) sometimes causes the foramen
magnum to narrow or fuse with the atlas and thus may compress
the spinal cord or brain stem.
• Down syndrome, Morquio syndrome (mucopolysaccharidosis IV),
or osteogenesis imperfecta can cause atlantoaxial subluxation or
dislocation.
• [Morquio syndrome (referred to as mucopolysaccharidosis IV, MPS
IV, Morquio-Brailsford syndrome, or Morquio)[1] is a rare metabolic
disorder in which the body cannot process certain types
of mucopolysaccharides(long chains of sugar molecules), which the
body uses as lubricants and shock absorbers.]](https://image.slidesharecdn.com/craniovertebraljunctionanamolynew1-240511155451-19ca4d14/85/CRANIO-VERTEBRAL-JUNCTION-ANAMOLY-new-1-pptx-6-320.jpg)
CRANIO VERTEBRAL JUNCTION ANAMOLY new (1).pptx
- 2. INTRODUCTION • Craniocervical junction abnormalities are congenital or acquired abnormalities of the occipital bone, foramen magnum, or first two cervical vertebrae that decrease the space for the lower brain stem and cervical cord. • Anatomical and radiological aspects
- 3. Classification I. Bony Anomalies • A. Major Anomalies • 1. Platybasia • 2. Occipitalization • 3. Basilar Invagination • 4. Dens Dysplasia • 5. Atlanto- axial dis.
- 4. Classification • B. Minor Anomalies • 1.Dysplasia of Atlas • 2.Dysplasia of occipital condyles, clivus, etc. II. Soft Tissue anomalies 1. Arnold-Chiari Malformation 2. Syringomyelia/ Syringobulbia
- 5. Etiology • Etiology • Craniocervical junction abnormalities can be congenital or acquired. Congenital • Congenital abnormalities may be specific structural abnormalities or general or systemic disorders that affect skeletal growth and development. Many patients have multiple abnormalities. • Structural abnormalities include the following: • Os odontoideum (anomalous bone that replaces all or part of the odontoid process) • Atlas assimilation (congenital fusion of the atlas and occipital bone) • Congenital Klippel-Feil malformation (eg, with Turner or Noonan syndrome), often associated with atlanto-occipital anomalies • Atlas hypoplasia
- 6. Etiology • Chiari malformations (descent of the cerebellar tonsils or vermis into the cervical spinal canal, sometimes associated with platybasia) • General or systemic disorders that affect skeletal growth and development and involve the craniocervical junction include the following: • Achondroplasia (impaired epiphyseal bone growth, resulting in shortened, malformed bones) sometimes causes the foramen magnum to narrow or fuse with the atlas and thus may compress the spinal cord or brain stem. • Down syndrome, Morquio syndrome (mucopolysaccharidosis IV), or osteogenesis imperfecta can cause atlantoaxial subluxation or dislocation. • [Morquio syndrome (referred to as mucopolysaccharidosis IV, MPS IV, Morquio-Brailsford syndrome, or Morquio)[1] is a rare metabolic disorder in which the body cannot process certain types of mucopolysaccharides(long chains of sugar molecules), which the body uses as lubricants and shock absorbers.]
- 7. Etiology Acquired • Acquired causes include injuries and disorders. • Injuries may involve bone, ligaments, or both and are usually caused by vehicle or bicycle accidents, falls, and particularly diving; some injuries are immediately fatal. • RA (the most common disease cause) and Paget disease of the cervical spine can cause atlantoaxial dislocation or subluxation, basilar invagination, or platybasia. • Metastatic tumors that affect bone can cause atlantoaxial dislocation or subluxation. • Slowly growing craniocervical junction tumors (eg, meningioma, chordoma) can impinge on the brain stem or spinal cord.
- 8. PRESENTATIONS • Fusion of the atlas (C1) and occipital bone: Spinal cord compression if the anteroposterior diameter of the foramen magnum behind the odontoid process is < 19 mm • Atlantoaxial subluxation or dislocation (displacement of the atlas anteriorly in relation to the axis): Acute or chronic spinal cord compression • Platybasia (flattening of the skull base so that the angle formed by the intersection of the clival and anterior fossa planes is > 135°), seen on lateral skull imaging: Usually, no symptoms or cerebellar or spinal cord deficits
- 9. Occipitalization • Type I: Occipitalization (subtotal) with BI. • Type II: Occipitalization(subtotal) with BI & fusion of 2 nd & 3 rd cervical vertebrae. • Type III: occipitalization (Total or subtotal) with BI & maldevelopment of the transverse ligament. may be associated with various malformations like C2-C3 fusion, hemivertebra, dens aplasia and tertiary condyle.
- 10. Occipitalization
- 11. BASILAR INVAGINATION • Basilar invagination (upward bulging of the occipital condyles): A short neck and compression that can affect the cerebellum, brain stem, lower cranial nerves, and spinal cord. • The floor of the skull is indented by the upper cervical spine, & hence the tip of odontoid is more cephalad protruding into the FM. • Primary invagination – developmental • Secondary invagination -- Acquired. • Primary BI--- associated with occipitoatlantal fusion, hypoplasia of the atlas, a bifid posterior arch of the atlas, odontoid anomalies. • 25 – 35% -- ACM , Syringomyelia , Hydrocephalous
- 13. Types of dens dysplasia • Type 1 (Os odontoideum) separate odontoid process • Type 2 (Ossiculum terminale) failure of fusion of apical segment with its base • Type 3 – Agenesis of odontoid base & apical segment lies separately. • Type 4 – Agenesis of odontoid apical segment • Type 5 –Total agenesis of odontoid process.
- 14. Types of dens dysplasia
- 15. ATLANTO-AXIAL DISLOCATION OR INSTABILITY GREENBERG’S CLASSIFICATION; • Incompetence of the odontoid process- • Incompetence of the Transverse ligament WADIA CLASSIFICATION : • Group I: AAD with occipitalization of atlas & fusion of C2 & C3. • Group II: odontoid in competence due to its maldevelopment with no occipitalization of atlas. • Group III: odontoid dislocation but no maldevelopment of dens or occipitalization of atlas.
- 17. Syringomyelia Type 1 : Syringomyelia with obstruction of Foramen Magnum and dilatation of central canal ( Developmental Type) • 1. With type 1 Chiari malformations • 2. With other obstructive lesion of foramen magnum Type 2 : Syringomyelia without obstruction of Foramen Magnum ( Idiopathic Developmental Type) Type 3: Syringomyelia with other diseases of spinal cord ( Acquired Types ) • 1. Spinal cord tumors ( usually intramedullary hemangioblastoma) • 2. Traumatic myelopathy • 3. Spinal Arachdnoitis and pachymeningitis. • 4. Secondary myelomalacia from cord compression ( tumour , spondylosis ) , infarction , hematomyelia Type 4 : Pure hydromyelia ( developmental dilatation of the cental canal ) with or without hydocephalus.
- 18. Klippel- Feil Syndrome • Type 1- Massive fusion of cervical and often upper thoracic vertebra. Associated with short neck, low hairline and restricted neck movements • Type 2- associated with fusion of several cervical vertebra • Type 3 – associated with fusion of 2 cervical vertebra. Other associated anomalies:- Sprengel shoulder
- 20. Cervical canal stenosis • Foramen Magnum: 25-30mm • C1 25-30mm • C2 20-25mm • C3-C7 ≥ 14mm
- 21. Arnold-Chiari Malformation • Type 1- Cerebellomedullary malformation without meningocoele with variable downward displacement of cerebellar tonsils into spinal canal • Type 2. Cerebello-medullary malformation with meningocoele or meningomyelocoele along with variable downward displacement of inferior vermis of cerebellum, brainstem and IVth ventricle into cervical canal
- 22. Presenting Features • Cervical symptoms and signs • Myelopathic Features- long tract involvement and wasting • CN involvement- IX, X, XI, XII, V, AND rarely VIII, VII • Cerebellar symptoms/signs- Nystagmus, Ataxia, intention tremor, dysarthria • Transient Attack of V-B insufficiency • Features of Raised ICT- usually seen in Pts. Having basilar impresssion and/or ACM
- 23. Symptoms and Signs • Symptoms and signs can occur after a minor neck injury or spontaneously and may vary in progression. Presentation varies by degree of compression and by structures affected. The most common manifestations are • Neck pain, often with headache • Symptoms and signs of spinal cord compression • Neck pain often spreads to the arms and may be accompanied by headache (commonly, occipital headache radiating to the skull vertex); it is attributed to compression of the C2 root and the greater occipital nerve and to local musculoskeletal dysfunction. Neck pain and headache usually worsen with head movement and can be precipitated by coughing or bending forward. If patients with Chiari malformation have hydrocephalus, being upright may aggravate the hydrocephalus and result in headaches.
- 24. Symptoms and Signs • Neck appearance, range of motion, or both can be affected by some abnormalities (eg, platybasia, basilar invagination, Klippel-Feil malformation). The neck may be short, webbed (with a skinfold running approximately from the sternocleidomastoid to the shoulder), or in an abnormal position (eg, torticollis in Klippel-Feil malformation). Range of motion may be limited. • Brain compression (eg, due to platybasia, basilar invagination, or craniocervical tumors) may cause brain stem, cranial nerve, and cerebellar deficits. Brain stem and cranial nerve deficits include sleep apnea, internuclear ophthalmoplegia (ipsilateral weakness of eye adduction plus contralateral horizontal nystagmus in the abducting eye with lateral gaze), downbeat nystagmus (fast component downward), hoarseness, dysarthria, and dysphagia. Cerebellar deficits usually impair coordination. • Vertebrobasilar ischemia can be triggered by changing head position. Symptoms may include intermittent syncope, drop attacks, vertigo, confusion or altered consciousness, weakness, and visual disturbance.
- 25. Symptoms and Signs • Spinal cord compression involves the upper cervical cord. Deficits include spastic paresis in the arms, legs, or both, caused by compression of motor tracts. Joint position and vibration senses (posterior column function) are commonly impaired. Tingling down the back, often into the legs, with neck flexion (Lhermitte sign) may occur. Uncommonly, pain and temperature senses (spinothalamic tract function) are impaired in a stocking-glove pattern. • Syringomyelia (cavity in the central part of the spinal cord) is common in patients with Chiari malformation. It may cause segmental flaccid weakness and atrophy, which first appear or are most severe in the distal upper extremities; pain and temperature senses may be lost in a capelike distribution over the neck and proximal upper extremities, but light touch is preserved.
- 26. INVESTIGATIONS • X Rays -Antero-posterior view -Lateral view - Open mouth view for dens • Stress X-Rays (neutral, flexion, extention) • CT Scan and 3D reconstruction • MRI conventional and dynamic • Myelogram & Ventriculogram • Angiography
- 27. Treatment of CV anomalies Treatment of A-A dislocation • Conservative treatment- For patients having only cervical symptoms or transient VB insufficiency with or without mild neurological deficit may be initially managed conservatively using – 1. Cervical Collar 2. Head- Halter Traction- if there is associated myelopathic features
- 28. Treatment of CV anomalies • Reduction and immobilization • Sometimes surgical decompression, fixation, or both • For most patients, reduction involves skeletal traction with a crown halo ring and weight of up to about 4 kg. Reduction with traction may take 5 to 6 days. If reduction is achieved, the neck is immobilized in a halo vest for 8 to 12 wk; then x-rays must be taken to confirm stability.
- 29. TREATMENT
- 30. Treatment of CV anomalies • If reduction does not relieve neural compression, surgical decompression, using a ventral or a dorsal approach, is necessary. If instability persists after decompression, posterior fixation (stabilization) is required. For some abnormalities (eg, due to RA), external immobilization alone is rarely successful; if it is unsuccessful, posterior fixation or anterior decompression and stabilization are required. • Several different methods of instrumentation (eg, plates or rods with screws) can be used for temporary stabilization until bones fuse and stability is permanent. In general, all unstable areas must be fused.