cv junction anomalies

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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