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Cranio-vertrable junction anamolies


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Cranio-vertrable junction anamolies

  2. 2. 1. Foramen magnum 2. Adjacent surrounding occipital bone (basiocciput) 3. First cervical vertebrae (atlas) 4. Second cervical vertebrae (axis)  Anomalies may be defects of development and not necessarily congenital and so may not manifest at birth
  3. 3. I. Bony Anomalies A. Major Anomalies 1. Platybasia 2. Occipitalization 3. Basilar Invagination 4. Dens Dysplasia 5. Atlanto- axial dis. 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 3. Dandy walker syndrome
  4. 4. • Lines , angles and indexes Chamberlain’s Line McGregor’s Line McRae’s Line  Klaus Height Index  Basal Angle  Boogard’s angle
  5. 5. CHAMBERLAIN’S LINE (Palato-occipital line)  joins posterior tip of hard palate to posterior rim of foramen magnum  Normally tip of dens lies 3.6 mm below this line.  In basilar invagination, the odontoid process bisects Chamberlain’s line Clivus Hard palate Occiput
  6. 6. McRae’s LINE (Foramen Magnum line)- Joins anterior and posterior edges of foramen magnum: sagittal diameter of foramen magnum. (Avg – 35mm) Tip of dens must be below this line If effective sagittal space for cervicomedullary junction is less than 20 mm in a child older than 8 yrs, neurological deficit is usually present
  7. 7. MCGREGOR’S LINE (Basal line)- Joins hard palate to lowest point of occipital bone Tip of dens should not exceed 5 mm above this line Basilar invagination Line position may vary with flexion and extension
  8. 8. WACKENHEIM’S LINE ( Clivus canal line) Line drawn along clivus and extrapolated into cervical spinal canal. Odontoid process should be ventral or tangential to it. Odontoid process transects this line in basilar invagination, atlantoaxial dislocation and anterior occipito atlantal dislocation Clivus Odontoid process
  9. 9. FISHGOLD’S DIGASTRIC LINE (Biventer line)- measured on frontal projection ,Connects the digastric grooves ( fossae for digastric muscles on undersurface of skull just medial to mastoid process) Line is normally 11mm (+/-4mm) above the atlanto-occipital junction. Upper limit of position for the odontoid tip Oblique in unilateral condylar hypoplasia FISHGOLD’S BIMASTOID LINE Odontoid process should be less than 10 mm above this line
  10. 10. HEIGHT INDEX OF KLAUS Distance between tip of dens and tuberculum cruciate line Nl- 40-41mm In basilar invagination- <30 mm
  11. 11. SPINOLAMELLAR LINE down along the fused spinous processes of C2 and C3 Normally should intersect posterior arch of atlas If atlas is fused, posterior arch is anterior to the line; posterior compression of spinal cord may occur
  12. 12. Basal angle –intersection line from nasion to centre of pitutary fossa ,another line in plan of clivus N =115 -145 >145 in platybasia BOOGARDS ANGLE -angle betn line drawn basion and opsthion and line from dorsum of sellae n basion N=<135 IN BI >135 SCHMIDT-FISCHER ANGLE Angle of axes of atlanto-occipital joints Normally 124-127 degrees Angle is wider in condylar hypoplasia
  13. 13. BA-BASAL ANGLE
  14. 14. Congenital fusion of cervical vertebrae Failure of normal segmentation of the cervical vertebrae/somite between 3rd and 8th weeks of fetal development (rather than a secondary fusion) Maurice Klippel and Andre Feil – 1912 Incidence – 1 in 42,000 births ; more in females Autosomal dominant inheritance – C2-C3 fusion. Autosomal recessive – C5- C6 fusion FEIL’S TRIAD : 1. Low posterior hair line 2. Short neck 3. Limitation of head and neck movements / decreased range of motion in cervical spine
  15. 15. Feil’s classification Type I – massive fusion of many cervical and upper thoracic vertebrae with synostosis Type II – fusion of only 1 or 2 vertebrae (with hemivertebrae , scoliosis, occipito atlantoid fusion) Type III – presence of lower thoracic and upper lumbar spine anomalies with I/II Type IV – sacral agenesis
  16. 16. Patients with upper cervical spine involvement tend to present at an earlier age than those whose with lower cervical spine involvement Rotational loss and lateral bending is usually more pronounced than loss of flexion and extension because latter movements take place mostly between occiput and atlas Scoliosis – some patients congenital due to involvement of thoracic spine , others scoliosis compensatory to cervical scoliosis
  17. 17. Webbing of soft tissues on each side of the neck (extending from mastoid process to acromion of shoulders)- ‘pterygium colli’ Assocd torticollis due to contracture of sternocleidomastoid muscle or bony abnormalities Facial asymmetry Sprengel deformity/ high scapula Scoliosis and/or kyphosis
  18. 18. Musculoskeletal sys- cervical rib, congenital fusion of ribs, abnormal costovertebral joints, syndactyly, hypoplastic thumb, hypoplasia of pectoralis major, hemiatrophy of upper or lower limbs, CTEV, sacral agenesis Urinary tract abnormalities – agenesis of kidney, horseshoe kidney, hydronephrosis, tubular ectasia, renal ectopia, double collecting system Cardiovascular- VSD, PDA, coarctation of aorta, patent foramen ovale
  19. 19. Deafness (absence of auditory canal and microtia) Synkinesia- involuntary paired movements of the hand ( mirror movements) Neurologic deficit- facial nerve Palsy, rectus muscle palsy, ptosis of eye, cleft palate, etc
  20. 20. Cervical spine routine x-ray followed by flexion/extension lateral X-rays. These may show flattening and widening of vertebrae, hemivertebrae or block vertebrae, instability. MRI with head flexed and extended will most accurately access subluxation and cord compression along with cord anomalies. X-rays of the T-spine because of extension of synostoses below the neck.
  21. 21. Failure of segmentation between the last occipital sclerotome and the first spinal sclerotome – partial/complete Anterior arch to clivus : posterior arch to occiput Signs and symptoms only in second decade of life due to gradual increasing ligament laxity and instability with aging Onset of clinical symptoms can be sudden and precipitated by relatively minor trauma – loss of movt b/w atlas and occiput increases stress at atlanto axial joint => instability Neurological symptoms due to Odontoid process projecting into foramen magnum Assocd – basilar invagination, occipital vertebra, Klippel Feil Radiology: cervical spine x-ray (flexion – extension ), CT, MRI Treatment – non-operative / surgery
  22. 22. OS ODONTOIDEUM independent osseous structure lying cephalad to the axis body in the location of the odontoid process. Dystopic – fuses with the occipital bone and moves with clivus Orthotopic – lies in the position of normal dens and moves with atlas and axis vertebrae HYPOPLASIA/ AGENESIS OF DENS
  23. 23. CLASSIFICATION: Type I A- normal odontoid with occipitalisation of atlas Type I B- normal odontoid without occipitalisation Type II- detachment of odontoid from body of axis or agenesis of part or whole of dens Diagnosis is radiological. Atlas-Dens interval of more than 5 mm in children and more than 3 mm in adults is diagnostic
  24. 24. Infections(Grisel’s synd):associated with inflammation of adjacent soft tissues of the neck Traumatic atlantoaxial / occipitoatlantal dislocation Degenerative(ligamentous disruption at CV junction) Inflammatory (RA, ankylosing spondylitis): Down’s syndrome :due to laxity of transverse ligament Tumours ( chordoma, syringomyelia, NF )
  25. 25. The gap between the occipital condyles and the condylar surface of the atlas is widened to more than 5 mm.
  26. 26. Primary developmental defect Deformation of the basiocciput – upward indentation or invagination of base of skull into posterior fossa Prolapse of the vertebral column upward into the skull at the base  BASILAR IMPRESSION – Acquired form of basilar invagination secondary to softening of skull Eg. Paget’s disease, OI, hyperparathyroidism, osteomalacia, rickets  PLATYBASIA –  flattening of the skull - Abnormal obtuse basal angle formed by clivus and floor of anterior fossa – if exceeds 1450
  27. 27. Clinical features due to compression of neural structures at the cervicomedullary junction Suboccipital headache due to irritation of 2nd cervical nerve, lower cranial nerve symptoms, cerebellar symptoms( nystagmus ), progressive quadriparesis Often associated with other developmental bony anomalies
  28. 28. • 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
  29. 29. Progressive degenerative/ developmental disorder of the spinal cord, characterized clinically by brachial amyotrophy, suspended dissociative sensory loss, and pathologically by cavitation in the central region of the spinal cord. 90% cases associated with ACM type I. Types I: Syrinx with obstn of the foramen magnum Type II: Syrinx without obstn of the foramen magnum Type III: Syrinx with other diseases of the spinal cord Type IV: Pure hydromyelia Syringobulbia: the lower brainstem equivalent of syringomyelia, usually co-exists
  30. 30. Minimally involved patients lead normal lives with only minor restrictions. Should avoid contact sports that place neck at risk. For mechanical symptoms, cervical collar, analgesics, NSAIDS, or careful traction can be used. For neurologic compromise a thorough work-up to find the exact area of irritation, then fusion of the appropriate segments posteriorly. Decompression may be employed based on the site of the stenosis. Dislocations and basilar invagination are treated by careful traction followed by posterior fusion. Neurologic deficits and persistent pain are indications for surgery
  31. 31. MANAGEMENT OF REDUCIBLE DEFORMITIES Primary goal is stabilization reducing the compression on brainstem and spinal cord MANAGEMENT OF IRREDUCIBLE DEFORMITIES Decompression VENTRAL AND DORSAL APPROACHES WITH FIXATION IF NEEDED