Cv junction anomalies GMC Kota Neurology

1. Dr. RAHI KIRAN.B
SR NEUROLOGY
GOVT MEDICAL COLLEGE, KOTA

2. Atlanto Occipital
Synovial joint B/w Lateral masses of atlas and occipital condyles.
Movement – Flexion-10° & Extension-25°
Atlas &axis – 4 synovialjoints
2 median –front &back of dens (Pivot variety)
2 lateral –b/w opposing articular facets (Plane variety)
Each joint has its own capsule &synovial cavity.
Rotation is upto 90*&approx ½ occurs at the A-A joint.

3. Normal landmarks on coronal views –
the occipital condyles (1), lateral
masses of the atlas (2), odontoid
process (3), axis body (4), and tips of
the mastoid processes (5) (the last is
seen only in the diagram).

5.  Principal stabilizing ligaments of C1-
-Transverse atlantal ligament
-Alar ligaments
 Secondary stabilizing ligaments of CVJare more elastic &weaker than the
primary ligaments.
-Apical ligament
-Anterior &posterior A-O membranes
-Tectorial membrane
-Ligamentum flavum
-Capsular ligaments

8.  Structures related are –
Caudal brainstem (Medulla)
Fourth ventricle
Rostral part of spinalcord
Lower cranial (9,10,11,12)&upper cervical nerves
(C1,C2, and C3 nerves with both rami).
In cerebellum, only the tonsils, biventral lobules &the
lower part of the vermis (nodule, uvula &pyramid)

9. Normal Landmarks – Lateral View

10. I. Bony Anomalies
A. Major Anomalies
1.Platybasia
2.Occipitalization of atlas
3. Basilar Invagination
4. Dens Dysplasia
5.AAD
B.Minor Anomalies
1. Dysplasia ofAtlas
2. Dysplasia of
occipital condyles,
clivus, etc.
1. Arnold-ChiariMalformation
2. Syringomyelia/Syringobulbia
II. SoftTissueanomalies

11.  Congenital-
Malformation of occipital sclerotomes
Clivus segmentation anomalies
Condylar hypoplasia
Assimilation ofatlas
Malformation of atlas
 Assimilation of atlas
 Atlantoaxial fusion.
 Aplasia of atlas arches.
Malformation of axis.
 Irregular Atlantoaxial
segmentations.
 Dens dysplasia
Segmentations failure of c2-c3

12.  Developmental andacquired
foramen magnum-stenosis
Sec.basilar invagination-
Atlantoaxial instability
Spontaneous rotatory subluxation-
Grisel syndrome
1. down syndrome
2. Ehlers danlos syndrome
3. MPS
4. Trauma
5. Infection –TB
6. Tumors-Mets, chordom,
osteoblastoma, NF
1. OI
2. Pagetsds
3. Osteomalacia&rickets
4. RA

13.  Age of Onset –
 Any Age
 May remain Asymptomatic
 Mode of Onset
 Usually insiduous
 Frequently Trivial Trauma is the precipitating cause

14.  Cervical pain - suboccipital region radiating to vertex, stiffness in 85%
 Myelopathy - long tract involvement and wasting
 CN – mc-hearing loss, IX, X,XI,XI in 20%
 Vascular - in 20% Transient Attack of V-B insufficiency
 Sensory symptom of post. column involvement.
 Cerebellar symptoms/signs- Nystagmus, Ataxia, intention tremor, dysarthria
 Features of Raised ICT- basilar impresssion and/or ACM

15.  X Rays
 -Antero-posterior view
 -Lateral view
 -Open mouth view for dens
Stress X-Rays (neutral, flexion,extention)
CT Scan and 3Dreconstruction
MRI conventional and dynamic
Angiography

16. Craniometry of the CVJ uses a series of lines, planes & angles to define the
normal anatomic relationships of the CVJ.
These measurements can be taken on plain X rays,3D CT or on MRI.
No single measurement is helpful.
disadvantage --anatomic structures and planes vary within a normal range.

17. Parameter Normal rangelimits
A. PLATYBASIA
B. BASILAR INVAGINATION
C. ATLANTO-AXIALDISLOCATION *
• Basal angle
• Boogard’s angle
• Bull’s angle
< 140 degree
< 136degree
< 13degree
< one third of odontoid above this line
< 5 mm
odontoid lies below this
> 35 mm
• Chamberlain’s line
• Mcgregor’s line
• Mcrae line
• Klaus height index
• Atlanto-odontoid space upto 3 mm in adults
upto 5 mm in children

18. From tip of hard palate to opisthion.
For BI-if the tip of the dens is >3 mmabove

19.  Posterior tip of Hard palate to lowest part of Occiput
 Odontoid tip >5mm above  BI
 Should be used when lowest part of occipital bone is
not Foramen Magnum.

20.  Line drawnalong clivus into cervical spinal canal
 Odontoid is ventral and tangential to this line
If not –suggest AAD or BI
 normally ranges from 150 in flexion
to 180 extension .
 Ventral spinal cord compression may
occur when the angle is less than 150.

21. Joins anterior and posterior edges of Foramen magnum
Tip of odontoid is below this line.
When sagittal diameter of canal <20mm, in patient of >8yr of age neurological
symptoms occur – Foramen Magnum Stenosis

22. Distance between tip of dens and internal
occipital protruberence
40-41mm normal
In basilar invagination <30 mm

23. Line representing prolongation of hard palate and line
joining the midpoints of the ant &post arches ofC1.
Normal : <100
Basilar invagination - >130

24.  Connects the digastric grooves
 Tip of the dens and atlanto-occipital joint
normally project 11 mm and 12 mm below
this line respectively.
 For BI

25. Line connecting tip of mastoid
process.
Odontoid process should be less than
10mm above this line – BI

26. Nasion to tuberculum sella
Tuberculum sellae to thebasion along plane of the
clivus
 Normal – 1240- 142
> 1400 = platybasia
< 1300is seen inachondroplasia

27. between Dorsum sellae to Basion &McRae’s line.
Average – 1220
> 1350 - platybasia

28. Range between 124-127.
Wider in occipital condyle hypoplasia.
O
C2
AAJT
AO JT
C1 C1

31.  Atlantoaxial Dislocation (AAD) - 46.4%
 Chiari I (Cerebellar herniation) - 42.8%
 Syrinx -32.1%
 Occipitalisation of atlas (OA) - 28.57%
 Basilar invagination (BI) - 21.4%
 combination - OA+AAD - 20% patients.
 BI+OA - 14.2%
 BI +OA+AAD - 7.1% patients
 Traumatic - Odontoid #- 90%
AAD -10%

32. abnormally obtuse basal angle, may be asymptomatic, not a measure of basilar
invagination.
>140 basal angle.

33. 50% of all cvj anomaly inindia.
Gradual or sudden onset by trauma
It affects both sexes equally.symptoms in third and fourth
decades
No movement btw OA –leads increases stress at AA
joint –get instability
Associated –with basilar invagination, occipital vertebra,KF
syndrome

34.  Type I: Occipitalization (subtotal) with BI.
 Type II: Occipitalization(subtotal) with BI & fusion of 2nd & 3rd 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, tertiary condyle, etc
 Instability b/w atlas & axis is reducible in patients <15yrs but after that irreducible
state occurs.

35. BI implies that the floor of the skull is indented by the upper cervical spine &
hence the tip of odontoid protrudes into the FM.
Two types : primary - developmental
secondary - acquired.
Primary – a/w occipito atlantal fusion, hypoplasia of the atlas, a bifid
posterior arch of the atlas, odontoid anomalies.
 ACM or syningomyelia - in 25%-35% of these patients, cerebellum & vestibular
features (65%) , also vertebral artery anomalies.

36. 1. Hyperparathyroidism
2. Hurler's syndrome
3. Rickets/OM/Scurvy
4. Paget's disease.
5. Cleidocranial dysostosis
6. Osteogenesis Imperfecta

37.  Topographic typesof BI :
 Anterior BI : hypoplasia of the basilar process of the occipital bone.
 BI of theoccipital condyles (Paramedian BI)–Condylar hypoplasia
 BI in the lateralcondylar area.
 Posterior BI: posterior margin of the FM is invaginated.
 Unilateral BI.
 Generalised BI

39. AAD - excessive movement at the junction between the atlas (C1) and axis (C2)
as a result of either a bony or ligamentous abnormality.
Symptomatic – if spinal cord or nerve roots are involved.
 Incidence of AAD–
57% of all CVJanomalies.
8.3% of all causes of cervicalcompression

40. Group I: AAD with occipitalization of atlas &fusion of C2&C3.
Group II: odontoid maldevelopment
Group III: odontoid dislocation but no maldevelopment

41. Down syndrome -14-20%
Grisel syndrome
Rheumatoid arthritis
Osteogenesis imperfecta
Neurofibromatosis
Morquio syndrome -30-50%-Secondary to odontoid hypoplasia or aplasia

42. AAD - when >3 mm in adults &>5mm in children
AADI 3-6 mm - translig. damage
AADI >6mm - alar lig. damage also

43. Considered better method as it
directly measures the spinal canal
Normal : 19-32 mm atC1
PADI <14mm : predicts cord compression

44.  Riskfactors for cord compression in AAD-
AADI > 9 mm
PADI < 14 mm
Basilar Invagination, especially if associated
with AADof anydegree

45.  Fielding and Hawkins classification:
 Type I- simple rotatory displacement with an intact transverse ligament.
 Type II- injuries involve anterior displacement of C1 on C2 of 3-5 and a deficiency of
the transverse ligament.
 Type III -injuries involve greater than 5 mm of anterior displacement.
 Type IV-injuries involve the posterior displacement of C1 on C2.
 Both Type III and IV are highly unstable injuries.

46.  TREATMENT-
 Type I injuries (stable subluxations) –Collar.
 Type II injuries may be potentially unstable.
 Type III and IV rotatory displacements that are unstable are treated surgically with
a reduction and C1- 2 fusion.
 Techniques of fusion vary from sublaminar wiring techniques like Brooks or Gallie,
Halifax clamp, or transarticular screw of Magerl.

47. Type 1(Os odontoideum)-separate odontoid process
Type 2 (Ossiculum terminale) failure of fusion of apical
segment with itsbase
Type 3– Agenesis of odontoid base &apical segment lies
separately.
Type 4 – Agenesis of odontoid apical segment
Type 5 –Total agenesis ofodontoid process.

48. odontoid base is separate until the age of 8
Independent osseous structure lying cephalad to the
axis body in the location of the odontoid process.
Anterior arch of the atlas is rounded and hypertrophic
but the posterior arch ishypoplastic.
Cruciate ligament incompetence and A-A instability
arecommon

49. fusion of the terminal ossicle to the
remainder of theodontoid- by 12yrs
Confused with a type 1 odontoid fracture.
Stable when isolated
Odontoid process is usually normal inheight.

50.  Posterior rachischisis > aplasias and hypoplasia
 Total or partial aplasia of the posterior atlas arch.
 Isolated, is usually asymptomatic, but may be associated with
anterior AA subluxation.
 Simulating Jefferson fracture.

51.  Triad <50%
Decreased range of motion in the cervical spine
Short, webbed neck
Low hairline.
 flexion and extension are better preserved
 Type
1. Massive fusion of cervical and upper thoracic vertebra
2. Fusion of 2 cervical vertebra , scoliosis, OAfusion
3. Lower thoracic and upper lumber spine anomaly.
4. Sacral agenesis

52.  Scoliosis- 60%.
 Genito-urinary- 30%. m/c is absence of kidney.
 Sprengel's deformity- 35%
 Cardio-pulmonary-5-15%, m/c V.S.D.
 Deafness-30%, all types, MC mixed.
 Sykinesis-Mirror motions 20%.
 Cranio-cervical abnormalities- (25%)- Includes C1-C2 hypermobility and instability,
BI, Chiari I malformation, diastematomyelia, & syringomyelia.

53.  facial asymmetry, torticollis and neck webbing (pterygium colli) - 20%
 Ptosis of the eye, Duane's eye contracture, lateral rectus palsy, facial nerve palsy
and cleft palate.
 Upper extremity abnormalities, ie. syndactyly, hypoplastic thumb, supernumary
digits and hypoplasia of the upper extremity.

54.  Type 1- m/c -congenital tonsillar herniation, tonsillar ectopia, or tonsillar descent,
Syringomyelia in 50 to 70%.
 Type II -less common and more severe, almost invariably associated with
myelomeningocele. Symptomatic in infancy or early childhood. -caudal
displacement of lower brainstem (vermis, medulla, pons, 4th ventricle) through the
foramen magnum.
 Type III -herniation of cerebellum into a high cervical myelomeningocele.
 Type IV -cerebellar agenesis.
 type III and IV -exceedingly rare and incompatible with life

55. Chiari type I malformation.
(white line) down to the level of C1 posterior arch.

56.  No role for prophylactic treatment in an asymptomatic patient with an incidental.
 All symptomatic patients require surgical treatment.
 In hydrocephalus - primary treatment - shunting the ventricular system.
 symptomatic ventral compression from BI or retroflexion of the odontoid - ventral
decompression.
 syrinx with scoliosis - the initial treatment - posterior cervicomedullary
decompression.

57.  Patients presenting with pain (mainly headache and neck pain) & weakness
without associated atrophy –best results.
 Brain stem and cerebellar syndromes -good recovery
 Cranial nerve – moderate
 Sensory, central cord syndrome - syrinx- - poor.
 most prognostic of poor outcome - atrophy, ataxia, and scoliosis.

58.  <1% of all cases of spinal TB.
 Compression of CMJ could be due to granulation tissue, cold abscess or bony
instability & displacement.
 Waxing & waning picture .
 Ligaments are extensively infiltrated .
 Hyperaemic decalcification occurs.

59.  Radiological findings in 3 stages–
 Stage I: Retropharyngeal abscess with ligamentous laxity, bony architecture of C1-
C2 preserved.
 Stage II: Ligamentous disruption with AAD, minimal bone destruction &
retropharyngeal mass
 Stage III: marked destruction of bone, complete obliteration of anterior arch of C1
& complete loss of odontoid process, marked AAD & O-A instability.

60.  TREATMENT:
 Bed rest, cervical traction, evacuation of retropharyngeal abscess & prolonged
external immobilization along with ATT.
 Indications of Surgery :
 Gross bony destruction with instability
 Major neurological deficits
 Unstable spine following conservative Tx
 Surgery :
 Posterior fusion
 Anterior decompression with or without fusion

61.  20% of RA have AAD.
 Osteophyte formation (stabilizing effect) does not occur secondary to deficient
osteogenesis(characteristic of RA).
 Loss of tensile strength & stretching of TL -AAD.
 Odontoid process –osteoporosis, angulation/#.

62.  Asymptomatic without AAI -left alone.
 INDICATIONS FOR SURGICAL TREATMENT
▪ onset of Neurological signs.
▪ Persistent cervical symptoms with pain, muscle spasm and occipital neuralgia
resistant to conservative treatment
▪ younger persons with vigorous life style- indicated even in the absence of
cervical or neurological symptoms

64.  Youmans textbook ofneurosurgery
 ATextbook of Neuroanatomy GARTNER and Rhoton
 Arnold H. MenezesCraniovertebral junction database analysis: incidence, classification,
presentation, and treatment algorithmsChilds Nerv Syst (2008) 24:1101–1108 DOI
10.1007/s00381-008-0605-9
 Management of Congenital Atlanto-Axial DislocationNeurology India, Vol. 50, No. 4, Dec,
2002, pp. 386-397 Review Article
 Uptodate.com
 Radiopedia.org

65. N Saggital
Diameter
Stenosis
Foramen Magnum 25 – 35 mm <25 mm
Cervical Canal
(C1)
25 -30 mm <20 mm
Cervical Canal
(C2)
20 – 25 mm <20 mm
Cervical Canal
(C3-C7)
16 – 22 mm <13 mm

66. Normal Landmarks – Lateral View
Nasion (1), Tuberculum sella (2), Basion (anterior margin of the foramen magnum) (3),
Opisthion (posterior margin of the foramen magnum) (4), Posterior pole of the hard palate (5),
Anterior arch of the atlas (6), Posterior arch of the atlas (7), and Odontoid process (8).

69. 1.nasion
2.tuberculum sella
3.basion (anterior margin of the
foramen magnum)
4.opisthion (posterior marginof the
foramen magnum)
5.posterior poleof the hard palate
6.anterior archof the atlas
7. posterior archof
the atlas
8. odontoid process