cv junction anomalies
TRANSCRIPT
CVJ ANATOMY-CLASSIFICATION&CLINICAL SIGNS
DR NILESH JAIN23.06.2007
THE TERM ‘CV JUNCTION’ REFERS TO THE OCCIPITAL BONE THAT SURROUNDS THE FORAMEN MAGNUM AND THE ATLAS AND THE AXIS VERTEBRAE
HISTORICAL ASPECT CHAMBERLAIN , 1939 : BASILAR INVAGINATION
GREENBERG , 1968 : CLASSIFIED ATLANTOAXIAL ANOMALIES
BELL , 1830 : FIRST DESCRIBED SPONTANEOUS ATLANTOAXIAL DISLOCATION
MECKEL , 1815 : MANIFESTATION OF OCCIPITAL VERTEBRAE
History
1886 – Giacomini described the first case of congenital AAD
1960 – Wadia-congenital AADs 1968 – Greenberg – classification
of AADs
CV jn -Embryology
Develops from the 4 occipital and upper 2 cervical somites.
The mesoderm caudal to neural plate condense into four
occipital somites, these are the precursors of ocipital
sclerotomes.
First Two - Basiocciput
Third - Jugular tubercles
* Fourth occipital sclerotome
Proatlas
Proatlas
Hypocentrum Centrum Neural arch
Ant tubercle of the Apex of the dens Ventral Dorsalclivus & Apical ligament Rostral Caudal
First spinal sclerotome
Atlas vertebra primarily formed from this sclerotome.
Sclerotome division
Hypocentrum Centrum Neural Arch
Anterior arch C1 Dens Inferior portion of (mid portion the posterior arch Of the odontoidprocess and fused with axis
Second spinal sclerotome
Develops into axis vertebra
Sclerotome division
Hypocentrum Centrum Neural Arch
Disappears Body of axis Facets & Posterior arch of axis
Surgical anatomy Constituents of CV jn
Osseous components and their articulations Ligamento-muscular elements Neuro-vascular structures
Characteristics of CV jn Mobility at the cost of stability Constantly changing structure and
kinematics –even in the post natal period Vital neuro-vascular relations
Atlas* Named after the mythical giant who carried the earth on his shoulder.* Thin Anterior and posterior arches•Sturdy Lateral masses – made up of a column of superior and inferior articular facets placed in a vertical line•No body
Axis:Forms the axis of rotationDens is a divorced body of C1Bifid spinous processInferior facet more posterior than superior facet
External craniovertebral ligaments
Internal Craniovertebral Ligaments
LIGAMENTS OF CVJ
POSTERIOR - POST. ATLANTOOCCIPITAL MEMBRANE:
EXTENDS FROM OCCIPITAL
BONE TO
POST. ARCH OF ATLAS
SHARP & THIN & DIRECT
CONTACT WITH ANT. CORTEX OF
POST. ARCH OF ATLAS
ANTERIOR LIGAMENTS
ANTERIOR LONGITUDINAL LIGAMENT EXTENDING FROM LOWER BORDER OF ANT.ARCH C1 TO BODY OF AXIS
ANTERIOR ATLANTO -OCCIPITAL MEMBRANE EXTENDS FROM ANT.EDGE OF FM TO ANT.ARCH C1
ANTERIOR LIGAMENTS
TECTORIAL MEMBRANE CEPHALIC EXTENSION OF PLL INSERTED INTO PROCESSUS BASILARIS 1 –2 cm ABOVE BASION
CRUCIATE LIGAMENT OCCIPITOTRANSVERSE
LIGAMENT: TO BASION INFERIOR LOGITUDINAL
BAND: TO AXIS BODY TRUE TRANSVERSE
LIGAMENT
TRUE TRANSVERSE LIGAMENT STRONG HORIZONTAL
PORTION MAINTAINS THE
POSITION OF DENS IN SAGITTAL &
CRANIOCAUDAL DIRECTION
ARTICULATES WITH ODONTOID FACET
INSERTED LATERALLY IN BONY PROMINENCE IN INNER ASPECT OF CONDYLES
IT IS 8mm IN HEIGHT AND 2-3 MM THICK IN MIDLINE
ANTERIOR LIGAMENTS BARKOWS LIG- FROM TIP
OF DENS TO ANT.LAT. FM RIM
APICAL LIG- TIP OF DENS TIP OF DENS TO MIDDLE PART OF FM RIM
GRUBERS LIG- TRANSVERSE LIG TO TIP OF DENS
ALAR LIGAMENT- VERY STRONG
LIGAMENT
6 – 8 mm IN
DIAMETER
DENS TIP TO
LATERAL PART OF
RIM OF FM
BLOOD SUPPLY
VERTIBRAL ARTERIES - ANT. & POST. ASCENDING a.
CAROTID ARTERY : ANT. ASCENDING a.
FORMS AN APICAL ARTERIAL ARCADE IN THE REGION OF ALAR LIGAMENT & SEND
PERFORATORS
VENOUS DRAINAGE : PERIODONTAL VENOUS PLEXUS & SUBOCCIPITAL EPIDURAL SINUS DRAIN TO
PHARYNGOVERTIBRAL VEINS
LYMPHATIC DRAINAGE :
CV JUNCTION DRAINS TO
RETROPHARYNGEAL
LYMPH NODES & THENCE TO
DEEP JUGULAR CERVICAL CHAIN
RETROGRADE INFECTION OF CV JUNCTION FROM
PHARYNX , SINUSES & RETROPHARYNGEAL AREAS :
GRISEL’S SYNDROME
CLASSIFICATION OF CRANIOVERTEBRAL JUNCTION ANOMALIES
Classification of AAD Menezes classified CV jn
anomalies into two broad categories Developmental(Primary) Congenital and Acquired(Secondary)
CV jn anomalies and AAD classifications overlap
I Congenital anomalies & malformations of the cranio vertebral junction
1.Manifestation of Occipital bone a.Clivus segmentations b.Remnants around FM. c.Atlas variants. d.Dens segmentation anomalies.
2.Basilar invagination 3.Condylar hypoplasia 4.Assimilation of atlas B Malformation of atlas 1.Assimilation of atlas. 2.Atlantoaxial fusion 3.Aplasia of atlas arches
C.Malformation of axis 1.Irregular atlantoaxial
segmentation. 2.Dens dysplasias a.Ossiculum terminale persistens. b.Os odontoideum c.Hypoplasia-aplasia 3.Segmentation failure of C2-C3
II Developmental & acquired abnormalities of the CV Junction
A.Abnormalities of Foramen magnum 1.Sec. Basilar invagination (e.g.
Pagets disease, osteomalacia,renal resistance rickets)
2.Foraminal stenosis (e.g.achondroplasia
B.Atlantoaxial instability 1.errors of metabolism(e.g Morquio
s disease) 2.Downs syndrome. 3.Infections(e.g Grisels syndrome) 4.Inflammatory (e.g Rheumatoid
arthritis)
5.Traumatic occipitoatlantal & atlantoaxial dislocation;Os odontoideum)
6.Tumors(neurofibromatosis,syringomyelia)
7.Miscellaneous(e.g fetal warfarin syndrome,Conradis syndrome)
Greenberg’s Classification of AADI Incompetence of odontoid processA. Congenital 1. Type I Separate odontoid: OS odontoideum2. Type II Free apical segment: Ossiculum Terminale3. Type III Agenesis of odontoid base4. Type IV Agenesis of Apical segment5. Type V Agenesis of odontoid process totallyB. Traumatic1. Acute2. Chronic C. Infectious e.g TuberculosisD. Tumors1. Primary2. Metastatic
II Incompetence of Transverse Atlantal ligament
A. Congenital:1. Idiopathic2. Mongolism
B. Traumatic1. Acute - Rupture of TAL2. Chronic - Assimilation of atlas
- Block vertebrae C2 & C3
C. Hyperaemic1.Infection –Bacterial/viral(Grisel’s syndrome)/granulomatous2.Rheumatoid arthritis
Wadia proposed the following classification
Group I: AAD with* Occipitalization of atlas* Fusion of C2, C3 vertebrae* Odontoid process dislocated posteriorlyGroup II: AAD with * No occipitalization of atlas* No Fusion of vertebrae*Odontoid process dislocated because of its mal development Group III: AAD with* No occipitalization* No fusion of vertebrae* Odontoid is normal in shape and size to body of the axis.I & II are usually developmental and III is acquired
Other classifications Biomechanical
Translatory Rotary
Radiological Mobile Fixed
Clinical Reducible Irreducible
Common Bony CV Junction Anomalies
Basilar Invagination: The term Basilar Invagination was
used by Chamberlain in 1939 . This is a primary defect implying
prolapse of the vertebral column into the skull at the base.
Two types of Basilar invagination A Ventral:In this there is shortening of
the basiocciput so that clivus is short & horizontally oriented thus displacing the FM in an upward direction.
B.Paramesial :The condylar hypoplasia may be present so that clivus become dorsally displaced into posterior fossa but may be of normal length.
BI is commonly associated with an abnormal odontoid process invaginating into posterior fossa which leads to indentation on the pons,medulla or cervicomedullary junctionin a ventral manner.
Chiari Malformation is associated with BI in 25 – 30%cases.
OS Odontoideum
Definition - Dens has developed necessarily but has failed to fuse with body of the axis.
Two types: A. Orthotopic variety: OS lies in place of dens and moves with atlas and axis. B. Dystopic variety: OS lies near the skull-base and moves with clivus with which it may be fused.
Congenital Os odontoideum Traumatic Os Odontoidem 1. H/o Trauma - often present Always present2. Site of specification - Usually between base of dens andusually between the base body of the axis (below SAF)with apical segment of the dens (above supra articular facet)3. Line of separation - Always smooth Acutely irregular and not corticated and corticated 4. Associated cong. Anomaly - Absent often present
AAD -Definition AAD is not a disease per se , rather it’s
a manifestation of a spectrum of pathological states.
This is a condition in which the atlas(C1) slips over the
axis(C2) in the antero-posterior direction resulting in
neural structure compression between the two
vertebrae.
Bone & ligamentous structure help stabilize the atlanto axial region.
The transverse ligament is the most important structure.
Other structure involved are alar ligament ,accessory atlanoaxial ligaments & tectorial membrane.
A distance of >3mm in an adult & >4.5mm in a child between posterior surface of ant. Arch of C1 & ant. surface of dens is thought to be incompetence of TL with associated instability.
Clinical Presentation of CV junction anomalies The most interesting feature of the
clinical presentation is the diversity.This is due to compression of the lower brainstem,cervical spinal cord,cranial nerves,cervical nerve roots,& vascular supply.
Presentation may be insidious,or as false localizing sign, infrequently a rapid neurological progression followed by death.
The most common symptom is neck pain originating in sub occipital region with radiation to cranial vertex region -85%.
False localising signs:Usually motor monoparesis,paraparesis,& quadripresis.
Clinical featuresGENERAL EXAM : Abnormal general apperance.
KLIPPEL- FEIL SYNDROME :Traid of Low posterior hair
line, short neck and limitation of neck movements
OTHER DYSPLASTIC FEATURES:
high arch palate
poly/syndactyly
pes cavus
scoliosis
sprengel shoulder,
Myelopathic features
Motor deficits- legs more involved Cruciate paralysis Posterior tract symptoms-
Lhermitte sign Central cord syndrome Neck pain/ cough headcahe
Cranial nerve symptoms Lower cranial nerve paresis Hearing loss(most common)-25% Hypoglossal paralysis (Klaus 1969)
Brain stem/cerebellar signs Sleep apnea and dysphagia Nystagmus Gait ataxia
Vascular symptoms Syncope Vertigo Episodic paresis Transient visual loss. Due to vertebro basilar
insufficiency Present in 15 – 25% of cases.
The phenomenon of basilar migraine affects about 25% of children with BI & compression of the medulla.
This is usually involves compression of vertebro basilar arterial system.
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