Cv anomaly

1. CRANIO-VERTEBRAL
ANOMALIES
SPEAKER MODERATOR
Dr ROHIT GAUDE Dr ABHISHEK PATHAK
Dr RAVINDU

2. The craniocervical junction is a vital component in understanding the
function of the human central nervous system.
The craniovertebral junction (CVJ) comprises the occiput, atlas, and
axis.
Abnormal development of any of these components may lead to
altered structure, and therefore, altered function in the central nervous
system.

3. • Atlantoaxial dislocation, occipitalisation of atlas, and fusion of C2
and C3 vertebrae are the commonest anomalies occurring in India.
• Males are most commonly affected and a predisposing factor like
trivial neck trauma may be identified in nearly 50% of the cases.
• The signs and symptoms of these anomalies are diverse that include
local radicular Neck pain, high cervical cord compression, lower
cranial nerves palsy and cerebellar involvement.
• The clinical manifestations are often delayed into the second and
third decade because they are usually subtle

4. • Diagnosis is established only after plain radiographs of the cervical
spine in full flexion and extension positions.
• Magnetic resonance imaging is the ideal tool to use after plain
radiographs are obtained.
• It identifies the neural abnormalities as well as the osseous
compression.

5. • Lines and angles used in radiologic diagnosis of C.V
junction anomalies.
1) CHAMBERLAIN’S LINE
• Extends from the posterior margin of the hard palate to the
posterior margin of the foramen magnum (opisthion).
• The tip of the odontoid process normally lies below or just tangent to
the Chamberlain’s line.
• The odontoid projecting above this line is diagnostic of “basilar
invagination”.

6. 2)McGREGOR LINE
• McGregor proposed a modification of Chamberlain’s line (basal line),
extending from the posterior margin of the hard palate to the lowest
point of the occipital squamosal surface.
• McGregor determined that the tip of the odontoid process may
normally project above this line for a distance of 5 mm in females and
7 mm in males.
• It is generally considered abnormal, if the tip of the odontoid projects
more than 5 mm above Chamberlain’s line or 7 mm above
McGregor’s basal line.

7. 3) BASAL ANGLE
• Formed by the intersection of nasion– midsella and midsella–basion
tangents.
• The average angle is 134–135° with a minimum of 121° and a
maximum of 148–149°.
• An abnormally obtuse angle is the best indication of platybasia or
flattening of the skull base.
• it is frequently associated with basilar invagination.

8. 4) WACKENHEIM’S CLIVUS BASELINE
• It is constructed by drawing a line along the clivus and extending it
inferiorly into the upper cervical spinal canal.
• This line normally falls tangent to the posterior aspect of the odontoid tip.
• In addition to its use in describing CVJ abnormalities , this line is very useful
for assessment of CVJ traumatic injuries.
• If the line falls too far posterior to the odontoid, posterior craniocervical
dislocation may be present .
• if the lines actually intersects the body or base of the odontoid, anterior
craniocervical dislocation may be diagnosed.

10. 5) BOOGARD’S ANGLE
A line is drawn from basion to opisthion and
another line along the plane of clivus to the basion, intersecting the
first line.
The resultant angle formed is the boogards angle.
The normal value is 126° +/- 6° .
In platybasia it exceeds 136°.

11. 6) KLAUS HEIGHT INDEX
It is the distance between the tip of dens and tuberculum torcula line.
It represents the height or depth of the posterior fossa.
The mean value is 41+_4 mm.
A value of <35mm usually indicates Basilar invagination or Platybasia.

12. 7) McRAE’S LINE
Also called as the foramen magnum line.
It is constructed by joining opisthion to basion and corresponds to
effective diameter of the foramen magnum.
Normal diameter is around 40mm.
When effective saggital diameter is <20 mm, neurological symptoms
occur (termed as Foramen Magnum stenosis).

14. 8) ATLANTO-OCCIPITAL JOINT AXIS ANGLE
It is formed at the intersection of tangents drawn parallel to the
atlanto-occipital joints.
These tangents typically intersect at the center of the odontoid
process when the condyles are symmetric.
The average angle measures 124° to 127°.
The angle becomes more obtuse in the face of occipital condylar
hypoplasia and may even approach 180° or more.

16. 9) ATLANTO-DENTAL INTERVAL, ADI (PREDENTAL INTERVAL)
• It is the normal space between the posteroinferior margin of the
anterior arch of C1 and the adjacent anterior surface of the odontoid
process.
• It normally measures 3 mm in adults and as much as 5 mm in children
up to the age of 9 years.
• Widening of this space is associated with atlanto-axial instability, such
as in children with Down’s syndrome and muco-polysaccharidosis.

18. CLASSIFICATION OF CV ANOMALIES
1. Bony Anomalies
(A)Major anomalies
i) Platybasia
ii) Occipitalization
iii) Basilar invagination
iv) Dens dysplasia
v) Atlanto-axial dislocation
vi) Klippel-feil anomaly
(B) Anomalies of occipital condyles,
arch of atlas, clivus etc.
2. Soft tissue anomalies
i) Arnold-chiari malformation
ii) Syringobulbia and/or syringomyelia

19. ARNOLD CHIARI MALFORMATIONS
• These refer to a spectrum of congenital hindbrain abnormalities
affecting the structural relationships between the
1) cerebellum
2) brainstem
3) upper cervical cord
4) bony cranial base.

20. • Chiari type I malformation is the most common and the least severe
of the spectrum, often diagnosed in adulthood.
• Its hallmark is caudal displacement of peglike cerebellar tonsil below
the level of the foramen magnum referred to as congenital tonsillar
herniation, tonsillar ectopia, or tonsillar descent.
• The resultant impaction of the foramen magnum, compression of the
cervicomedullary junction by the ectopic tonsils, and interruption of
normal flow of cerebrospinal fluid (CSF) through the region produce
the clinical syndrome.

21. • Chiari type II malformation is less common and more severe, almost
invariably associated with myelomeningocele. Because of its greater
severity, it becomes symptomatic in infancy or early childhood.
• The type III malformation refers to herniation of cerebellum into a
high cervical myelomeningocele, whereas type IV refers to cerebellar
agenesis.
• The advent of MRI, with its capacity for sagittal views, has
revolutionized the diagnosis of Arnold chiari malformation.

22. Characteristic Chiari I Chiari II
Usual age of diagnosis Adults and older children Infants and young children
Clinical findings
• Headache and neck pain (worsened by cough or Valsalva
maneuver)
• Myelopathy
• Cerebellar symptoms
• Lower brainstem symptoms (eg, dysarthria, dysphagia,
downbeat nystagmus)
• Central cord symptoms (eg, hand weakness, dissociated
sensory loss, cape anesthesia)
• In infants, signs of brainstem dysfunction predominate:
swallowing/feeding difficulties, stridor, apnea, weak cry,
nystagmus
• Weakness of extremities

23. Primary anatomical abnormalities
• Herniation of cerebellar tonsils through foramen magnum,
producing compression of cervicomedullary junction
• Herniation of lower brainstem through foramen magnum
• Kinking of cervicomedullary junction
• "Beaking" of tectum
• Upward herniation of vermis through incisura
• Nearly vertical tentorium
Myelomeningocele No Always
Hydrocephalus Less than 10% of cases Very common
Syringomyelia 30-70% Common
Associated abnormalities
• Craniocervical hypermobility syndromes
• Klippel-Feil anomaly
• Hereditary connective tissue disorders and neurofibromatosis
type II
• Callosum corpus pellucidum septum of agenesis
• Hypoplasia or
• Enlargement of massa intermedia
• Heterotopias and gyral abnormalities
Shared associated abnormalities
• Basilar invagination
• Occipitalization of atlas
• Bifida of C1 posterior arch
• Foramen magnum variant anatomy
• Basilar invagination
• Occipitalization of atlas
• Bifida of C1 posterior arch
• Foramen magnum variant anatomy

24. • Chiari malformation type I, hypothesized to be a disorder of para-axial
mesoderm, which subsequently results in formation of a small
posterior fossa.
• The development of the cerebellum within this small compartment
results in overcrowding of the posterior fossa, herniation of the
cerebellar tonsils, and impaction of the foramen magnum.
• The greater incidence of Chiari I and II in females supports the view
that posterior fossa size is genetically determined, with males having
larger posterior fossa spaces than females, so that restriction of
posterior fossa size leads to hindbrain herniation more readily in
females than males.

25. • Symptoms of Chiari I develop as a result of 3 pathophysiological
consequences of the disordered anatomy
(1) compression of medulla and upper spinal cord
(2) compression of cerebellum
(3) disruption of CSF flow through foramen magnum.

26. • Compression of cord and medulla may result in myelopathy and
lower cranial nerve and nuclear dysfunction.
• Compression of cerebellum may result in ataxia, dysmetria,
nystagmus.
• The disordered flow of CSF through foramen magnum may result in
formation of syringomyelia and central cord symptoms such as hand
weakness and dissociated sensory loss.

27. • MRI is the imaging modality of choice.
• On sagittal imaging, the best plane for assessing for the presence of
Chiari I malformations, the tonsils are pointed, rather than rounded
and referred to as peg-like.
• MRI assesses the extent of tonsillar descent and descent of >5 mm is
chosen by most radiologists as the threshold value for labeling
tonsillar ectopia.

28. In a study by Mikulis et al, normal tonsillar position correlated with age .
As measured from a line drawn from the basion to opisthion, the tonsils may
be considered in normal position when they herniate up to,
1) 6 mm in children 0–10 years of age,
2) 5 mm in older children and young adults (10–29 years of age),
3) 4 mm in adults 30–79 years of age, and
4) 3 mm in individuals older than 80 years.
• Other important findings include a syrinx (50–70% of patients) that is
usually (but not always) cervical as seen on T2-weighted MRI.

30. •MANAGEMENT
• Patients with Chiari I malformations who have minimal symptoms
without syringomyelia can be treated conservatively.
• Mild neck pain and headaches can be treated with analgesics, muscle
relaxants, and occasional use of a soft collar.
• Frankly symptomatic patients should be offered surgical treatment.
• The goals of surgical treatment are decompression of
cervicomedullary junction and restoration of normal CSF flow in the
region of foramen magnum.

31. SYRINGOMYELIA
• Syringomyelia is the development of a fluid-filled cavity or syrinx
within the spinal cord.
• It is a condition with many possible causes.
• Hindbrain herniation is the most common cause, followed by spinal
arachnoiditis and also intraspinal tumors.
• Rarely no cause has been found in some patients and thus the term
idiopathic syringomyelia.

32. • Based on the MR imaging syrinx were classified into
1) Communicating,
2) Non-communicating, and
3) Atrophic types.

33. 1)Communicating syringes are caused by obstructions of
the CSF pathways distal to the outlets of the fourth ventricle.
In typical cases, there is generalized enlargement
of all four cerebral ventricles, and the central canal
participates in the hydrocephalic process like a "fifth ventricle.“
The etiologies of communicating syrinx include
1) subarachnoid hemorrhage
2) meningitis
3) neoplastic seeding of the leptomeninges
4) idiopathic

34. 2) Non Communicating syringes are dilations of the central canal that do
not communicate with the fourth ventricle are associated with
obstructions of the CSF pathways at or below the foramen
magnum.
Causes include
1) Chiari I malformation,
2) basilar invagination,
3) spinal arachnoiditis,
4) extramedullary compressions,
5) acquired tonsillar herniation.

35. 3) Atrophic syringes
which occur with myelomalacia (following trauma or infarction),
are associated with a reduction in the transverse dimensions of
the spinal cord on MR images

36. CLINICAL FEATURES
• Syringomyelia usually progresses slowly; the course may extend over
many years.
• Symptomatic presentation depends primarily on the location of the
lesion within the neuraxis.
• Syrinx interrupts the decussating spinothalamic fibers that mediate
pain and temperature sensibility, resulting in loss of these sensations,
while light touch, vibration, and position senses are preserved
(dissociated sensory loss).
• When the cavity enlarges to involve the posterior columns, position
and vibration senses in the feet are lost.

37. • A syrinx may extend into the medulla, producing a syringobulbia.
• This syndrome is characterized by dysphagia, nystagmus, pharyngeal
and palatal weakness, asymmetric weakness and atrophy of the
tongue, and sensory loss involving primarily pain and temperature
senses in the distribution of the trigeminal nerve.

38. MRI is the preferred method of investigation for diagnosis of syringomyelia
and clearly demonstrates cavities in the spinal cord.
MRI has two basic features for syringomyelia-
1-The presence of a cyst in spinal cord parenchyma; and
2- The associated abnormal signal of cord due to gliosis.
• Both these can be analysed on T1W and T2W images.
• T1W- The syrinx cavity has a signal intensity equal to or slightly higher than
CSF.
• T2W- Spinal cord tissue around a syrinx is often abnormal giving rise to
hyper-intense signal called myelomalcia.

39. MANAGEMENT
• No medical treatment is known for patients with syringomyelia.
However, a chronic, stable clinical course is common.
• Surgical interventions are Suboccipital and cervical decompression
includes suboccipital craniectomy; laminectomy of C1, C2, and
sometimes C3 .

40. Bony anomalies
BASILAR INVAGINATION
• In this the odontoid abnormally prolapses into the foramen magnum
and often associated with other osseous anomalies of the
craniovertebral junction, including atlanto-occipital assimilation,
incomplete ring of C1, and hypoplasia of the basiocciput, occipital
condyles, and atlas.
• basilar invagination and related malformation are related to acquired
instability of the atlanto-axial joint .

42. • Goel further classified basilar invagination into two categories based
on the anatomical inclination of odontoid process and clivus.
• In group A basilar invagination, there was a ‘fixed’ atlantoaxial
dislocation and the tip of the odontoid process ‘invaginated’ into the
foramen magnum and was above the Chamberlain line, McRae line of
foramen magnum and Wackenheim’s clival line.
• In group B, patients had normally inclined odontoid process and clivus
and the tip of the odontoid process was above Chamberlain’s line but
below McRae’s and Wackenheim’s lines.

43. • Essentially group A patients had atlanto-axial instability which was
absent in group B patients and brainstem girth was significantly
decreased in group A patients and not in group B patients.
• Plain radiography establishes diagnosis but MRI demonstrates extent
of cord compression and correlates with clinical neurological
involvement.
• The brainstem girth was markedly reduced in Group A patients, the
girth was only marginally affected or unaffected in Group B patients .

44. MANAGEMENT
• Goel’s classification for BI based on the presence (Group A) or
absence (Group B) of clinical and radiological instability between C1
and C2 helps surgeons to choose the best strategy to manage these
patients.
• Patients with BI and C1-C2 instability (group A) should be treated
with posterior fixation after reduction.
• Group B patients without C1-C2 instability benefit with posterior
foramen magnum decompression — the most common treatment for
patients in this group based on the principle of increasing the
posterior fossa volume.

45. ATLANTOAXIAL DISLOCATION
• Atlantoaxial facet joints are the center of mobility and also center for
instability of the atlantoaxial region.
• It is one of the most mobile joints of the body.
• Goel incriminates all craniovertebral instability to be due to
atlantoaxial dislocation.

46. • The atlantoaxial instability has been traditionally gauzed by the
atlantodental interval that signifies the abnormal movement of the
odontoid process away from the circle of atlas and toward the neural
structures in the spinal canal.
• The indentation of the odontoid process into the critical cervicomedullary
neural structures result in related symptoms.
• Such instability, also called as the type 1 atlanto-axial instabilty is the more
common form of atlantoaxial dislocation.
• Type 2 atlantoaxial instability, wherein the facets of atlas are dislocated
posterior to the facet of axis on lateral CT images.

47. Also classified as
1) Lateral atlantoaxial facetal dislocation is when the facet of the atlas is
dislocated lateral in relationship with the facet of axis.
2) Vertical atlantoaxial dislocation is when the odontoid process migrates
superiorly on flexion of the head and returns back entirely or incompletely
to normal position on head extension.
3) Rotatory atlantoaxial dislocation is when the facet of the atlas is dislocated
posterior in relationship with the facet of axis on one side and anterior in
its relationship on the contralateral side.
Such a dislocation results in torticollis.
4) Translatory atlantoaxial dislocation is a clinical situation when the facets
of atlas of both sides are dislocated anterior to the facets of axis.

48. • Unless symptoms of spinal cord compression occur,
Atlantoaxial Dislocation requires no treatment.
• Once symptoms arise, cervical spine stabilization is indicated until
surgical stabilization is performed.

50. KLIPPEL-FEIL ANOMALY-
The Klippel–Feil triad consists of a short neck, a low hairline and
limitation of neck motion due to congenital fusion of two or more
cervical vertebrae.
Although majority of the patients are asymptomatic, these are
especially prone to cervical cord injury after a minor fall or a major
traumatic episode.

51. • Feil, in 1919, described KFS into 3 groups according to degree of
involvement
• Type I- Massive fusion of many of the cervical and upper thoracic
vertebrae.
• Type II- the fusion at one or two interspaces with occipitoatlantoid
fusion, hemivertebrae or other abnormalities in the cervical spine ,
and
• Type III- cervical fusion in combination with lower thoracic or lumbar
fusion.

52. Patients may develop neurological symptoms that are secondary to
1)the degenerative disc disease of the adjacent mobile segments,
2)spinal instability from the hypermobility or from trauma, and
3)spinal stenosis in later decades of life.

53. The syndrome includes a complex of anomalies such as-
1) scoliosis (60%).
2) renal anomalies (35%) such as agenesis, dysgenesis, renal ectopia.
3)deafness (30%).
4)cardiovascular malformations (14%) such as atrial / ventricular septal
defect, Aortic coarctation.
5) cranial and facial asymmetry (13%)
6)cleft palate (10%)

54. • Most patients present with a short neck and a decreased cervical
rotation of movement, with a low hairline occurring in 40-50% of
patients.
• Decreased Rotation of movement is the most frequent clinical finding.
• In addition to fusion anomalies in the cervical spine, cervical spinal
stenosis can occur; though uncommon, it can increase the risk of
neurologic involvement

55. MANAGEMENT
• Surgical treatment of Klippel-Feil syndrome is indicated in a variety of
situations.
• Neurologic deficits and persistent pain are indications for surgery.

57. PLATYBASIA
Platybasia is abnormal flattening of the skull base.
Radiographically, platybasia results in abnormal obtuseness of the basal
angle and provides the basis for its evaluation.
Platybasia can occur in a variety of congenital disorders (e.g.craniofacial
anomalies , osteogenesis imperfecta, craniocleidodysostosis, Arnold-Chiari
malformation) or in acquired diseases (e.g., Paget disease, osteomalacia,
rickets, trauma).

58. OCCIPITALIZATION
Occipitalization of the atlas is a developmental anomaly in which part
or the complete atlas is fused to the occiput.
occipitalization is a failure of segmentation between the fourth
occipital sclerotome (proatlas) and the first cervical sclerotome during
embryonic development.
Occipitalization is the most common anomaly of the craniocervical
junction and majority of which remain asymptomatic.

60. REFERENCES
• Atul Goel ; Goel's classification of atlantoaxial “facetal” dislocation. J Craniovertebr Junction
Spine. 2014 Jan-Mar; 5(1): 3–8.
• Atul Goel ; Instability and basilar invagination . J Craniovertebr Junction Spine. 2012 Jan-Jun; 3(1):
1–2.
• Goel A; Basilar invagination, Chiari malformation, syringomyelia: A review. Neurol India 2009.
57:235-46.
• McRae DL and Barnum AS: Occipitalization of the atlas, AJR, 70:23, 1953
• Oldfield EH, Muraszko K, Shawker TH, Patronas NJ ; Pathophysiology of syringomyelia
associated with Chiari I malformation of the cerebellar tonsils. Implications for diagnosis and
treatment. J Neurosurg. 1994 Jan;80(1):3-15

61. THANK YOU