Radiology CV junction anomaly AK TMC.pptx

RADIOLOGY CLUB- 1
Dr. Akhil Anand
SR Neurology

History
 33 year old Male
 Weakness of both Upper limbs x 8 months (Right f/b left 4 months later)
 Distal weakness – difficulty in buttoning, mixing food, holding objects with Right hand f/b left hand
 No sensory symptoms
 No bowel/bladder symptoms

Clinical Examination
General examination:
 Short neck (Neck:Length ratio- 0.13)
 Low posterior hair line
CN’s: Right Horner’ syndrome
Motor
 Bulk- Right forearm wasting & hand muscle wasting
 Tone- Bilateral upper limb distal hypotonia.
Lower limb bilaterally spastic Right >Left
 Power:
B/L upper limb proximal muscles- Grade 5
B/L small muscles of hand- weak
B/L LL muscles- Grade 5
 Plantar- Bilaterally extensor
 Deep tendon reflexes:
BJ 0 2+
TJ 2+ 2+
SJ 0 2+
FF - -
KJ 3+ 3+
AJ 3+ 3+
 Examination of sensory system:
Pain, touch & temperature decreased
in right forearm & medial aspect of left
palm

Clinical Summary
 Bibrachial weakness with dissociated sensory loss
 Bipyramidal signs in lower limb
 Right sided Horner’s syndrome
 Without any bladder or bowel involvement

CVJ- INTRODUCTION
 CVJ is the transit zone between cranium & spine
 Most complex & dynamic area of the cervical region
 Encloses the soft tissue structures of the cervico-medullary junction (medulla, SC & lower CN’s)
 CVJ anomalies can be seen in all age groups, but clinical presentation is often delayed.
 CVJ anomalies may be congenital, developmental or due to malformation secondary to any
acquired disease process
 These anomalies can lead to neural or vascular compromise, obstructive hydrocephalus & CSF
dynamic flow abnormalities (syrinx)

CRANIO VERTEBRAL JUNCTION
Anatomy

Joints
Ligam
ents
C
VJ
Neural
struct
ures

Atlanto-Occipital joint
 Synovial joint between Lateral masses of atlas and
occipital condyles
 Between Articular facet of Occipital condyle & Superior
articular facet of C1

Atlanto-Axial joint
 Made of 4 Synovial joints
 2 median - front and back of dens (pivot joints)
 2 Lateral - between opposing articular facets (plane joints)

LIGAMENTS OF CVJ
Principal Secondary
Cruciate ligament:
Transverse
Ascending
Descending
Apical ligament
Alar ligaments
Ant & Post Atlanto-occipital membranes
Tectorial membrane
Ligamentum flavum
Capsular ligaments

NEURAL STRUCTURES AT CVJ
 Medulla
 Fourth ventricle
 Rostral part of spinal cord
 Lower cranial nerves (9,10,11,12)
 Upper cervical nerves (C1, C2 & C3 nerves)
 Cerebellum – tonsils & lower part of the vermis

CERVICO-MEDULLARY JUNCTION
 Defined anatomically as the point of
decussation of the corticospinal tracts
 Located near the superior margin of the C1
nerve roots

Classification of CVJ anomalies
Bony anomalies
Platybasia
Occipitalisation of atlas
Basilar invagination/impression
Atlanto-axial instability & dislocation
Dens dysplasia
Dysplasia of atlas
Dysplasia of occipital condyles, clivus
Soft tissue anomalies
Arnold Chiari
malformation
Syringomyelia
Syringobulbia

Important landmarks in Craniometry of CVJ

 Plain radiographs- Lateral view, AP view, Open mouth-Odontoid view, Flexion
Extension views
 CT- best for assessing bony structures of CVJ, useful in detection of occult
fractures/dislocations
 MRI- IOC, especially in evaluation of ligamentous structures & evaluation of cord
intensities/syringomyelia
 Dynamic MRI (Flexion-Extension study)- for assessing fixed/unstable AAD
IMAGING MODALITIES

BASILAR INVAGINATION
 Vertebral column is abnormally high and prolapsed into skull base
 Top of odontoid process protrudes into the Foramen magnum
 Radiologic diagnosis
 Can be Primary or Secondary

BASILAR INVAGINATION
 Secondary BI is associated with:
 Hyperparathyroidism
 Hurler's syndrome
 Rickets/Osteomalacia/Scurvy
 Paget's disease
 Cleidocranial dysostosis
 Osteogenesis Imperfecta
 Primary BI is usually associated with :
 Basi-occiput hypoplasia
 Occipital condyle hypoplasia
 Atlantooccipital assimilation
 Hypoplasia of atlas

BASILAR- INVAGINATION v/s IMPRESSION
CONGENITAL = INVAGINATION ACQUIRED = IMPRESSION
Normal bone of Foramen Magnum Softened bone of Foramen Magnum
CAUSES:
Osteogenesis imperfecta
Klippel-Feil syndrome
Achondroplasia
Chiari malformation
Cleidocranial dysostosis
CAUSES:
Rheumatoid arthritis
Paget’s disease
Hyperparathyroidism
Osteomalacia & Rickets

MCRAE LINE
 aka ‘Foramen magnum line’
 Join antr and postr edges of foramen magnum (basion
to opisthion)
 Normal - odontoid 5mm below this line
 Basilar invagination- if dens above this line
 Sagittal diameter <20mm - Foramen magnum stenosis

CHAMBERLAIN LINE
 From tip of hard palate to opisthion
 Normal - tip of dens usually below or tangential to this line
 Tip of dens >3mm above - Basilar invagination

MCGREGOR LINE
 Used when opisthion cannot be identified on
radiographs
 From hard palate to lowest point of occipital
bone
 If dens >5mm above this line - BI

Mc ‘RAY’ - 0mm
Chamberlain – 3mm
Mc G r e g o r – 5mm

HEIGHT INDEX OF KLAUS
 Distance between tip of dens and line joining tuberculum & torcula/internal
occipital protuberence
 Normal: 40-41mm
 In Basilar invagination : <30mm

WACKENHEIMS CLIVUS CANAL LINE
 aka ‘Basilar line’
 line drawn along slope of clivus into cervical spinal canal
 Normally: Odontoid is ventral and tangential to this line
 In BI: Tip of dens will intersect this line

FISHGOLDS DIGASTRIC LINE
 Connects digastric grooves
 Normally tip of dens is 11 mm below this line
 If tip of dens <11m below this line - s/o BI

FISHGOLDS BIMASTOID LINE
 Line connecting tips of mastoid processes
 Normally tip of dens <10mm above this line

PLATYBASIA
 Flattening of skull base
 Mostly associated with Basilar invagination
 Platybasia alone does not usually cause
symptoms unless it is associated with basilar
invagination

WELCHER BASAL ANGLE
 Angle between nasion - tuberculum line &
tuberculum - basion line
 Average - 132 degree
 Should be less than - 140 degree
 If >140 degree - Platybasia

BOOGARD’S ANGLE
 Between dorsum sellae to basion and Mc Rae line
 Avg - 122 degree
 >135 degree - platybasia

CEREBELLAR TONSILAR HERNIATION
 Perpendicular distance from the tip of cerebellar
tonsils to McRae line
 Above foramen magnum- normal
 <3mm - low lying tonsils (Normal)
 >5mm - Chiari I malformation

ATLANTO-OCCIPITAL ASSIMILATION
 Fusion of the atlas (C1) to the occiput either complete/incomplete
 Occurs in approximately 0.5% (range 0.08-3%) of the population
 May be Associated with:
 Fusion of C2 and C3 (occurs in 50% of cases)
 Dysplastic C2
 Basilar invagination
 Cleft palate
 Cervical ribs
 Urinary tract anomalies

Incomplete Atlanto-occipital Assimilation

FORAMEN MAGNUM STENOSIS
 Margins:
Anterior margin- Basion
Posterior margin- Opisthion
 Normal FM diameter in adults: 25-35mm
 Less than 20mm- FM stenosis

SYRINGOMYELIA
 A cystic collection that occurs within the spinal cord around the central canal.
 Hydromyelia- dilatation of the central canal of the spinal cord (thus the lesion is
lined by ependyma)
 Syringomyelia- cystic dissection through the ependymal lining of the central canal
and a CSF collection within the cord parenchyma itself (lesion is not lined by
ependyma)
 Characteristically, located in cervicothoracic cord- C2 to T9 being the most common
location

SYRINGOMYELIA- IMAGING
CT
 The syrinx may be appreciated as an area of decreased attenuation, similar to that
of CSF, within the spinal cord.
MRI
The syrinx follows CSF signal characteristics on all sequences:
 T1: hypointense
 T2: hyperintense, although there may be hypointense regions representing flow or
pulsation artifact

Craniometry of this patient
 Dens is above Mcrae line
 Tip of dens – 18.8mm above Chamberlains line
 Tip of Dens 20 mm above McGregor line
 Klaus height index – 104mm
 Welcher’s basal angle - 137 degree
 Boogard’s angle- 131 degree
 Foramen magnum axial diameter – 15mm
 Low lying cerebellar tonsils (2.9mm)
s/o Basilar Invagination
No Platybasia
s/o FM stenosis

CT findings in this case
 Incomplete atlanto-occipital assimilation- The anterior arch and bilateral
atlantooccipital joints are fused to occipital bone
 Abnormal pointed Odontoid process
 Dysplastic C2 vertebra
 Basilar invagination

MRI findings in this case
 Incomplete atlanto-occipital assimilation- The anterior arch and bilateral atlantooccipital joints
are fused to occipital bone
 Abnormal pointed Odontoid process & Dysplastic C2 vertebra
 Basilar invagination
 Crowding of foramen magnum with indentation on the medulla (reduced foramen magnum diameter)
 Minimal inferior ectopia of bilateral cerebellar tonsils approximately 2.9 mm below level of foramen
magnum.
 Long segment syrinx noted from C2/C3 disc level to mid D5 vertebral body level

FINAL IMPRESSION
 Basilar Invagination
 Atlanto-occipital assimilation
 Foramen magnum stenosis
 Long segment Syrinx

TAKE HOME
POINTS….
Platybasia
Basal angle
Boogard angles
>140 degree
>135 degree
Basilar invagination
McRae line
Chamberlains line
McGregor line
Odontoid below this line
<3mm
<5mm
Cerebellar tonsillar
herniation
Tip of cerebellar tonsils to Mcrae line >3mm
Foramen Magnum
stenosis
FM diameter <20mm

Radiology CV junction anomaly AK TMC.pptx

More Related Content

Similar to Radiology CV junction anomaly AK TMC.pptx (20)

Recently uploaded (20)

Radiology CV junction anomaly AK TMC.pptx

Editor's Notes