CRANIO VERTEBRAL JUNCTION ANAMOLY

1. Cranio-Vertebral Anomalies

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

12. BASILAR INVAGINATION

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.

16. ATLANTO-AXIAL DISLOCATION OR
INSTABILITY

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

19. Klippel- Feil Syndrome

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.