HAVE CRANIO-VERTEBRAL HAVE CRANIO-VERTEBRAL JUNCTION ANOMALIES BEEN JUNCTION ANOMALIES BEEN OVERLOOKED AS A CAUSE OVERLOOKED AS A CAUSE

OF VERTEBRO-BASILAR OF VERTEBRO-BASILAR INSUFFICIENCY?INSUFFICIENCY?

Deepak Agrawal, Naveen K*, SS kale, C S Bal*,Deepak Agrawal, Naveen K*, SS kale, C S Bal*,A K MahapatraA K Mahapatra

Departments of Neurosurgery and *Nuclear medicine,Departments of Neurosurgery and *Nuclear medicine,All India Institute of Medical Sciences, New Delhi-All India Institute of Medical Sciences, New Delhi-

110029110029

BACKGROUNDBACKGROUNDassociation of VBI with CVJ association of VBI with CVJ

anomalies is severely anomalies is severely underestimatedunderestimated

x-rays of the Cx spine are done in only x-rays of the Cx spine are done in only 30% of pts with VBI & 30% of pts with VBI & only 11% pts only 11% pts have proper flexhave proper flexnn/ext/extnn x-rays done x-rays done

Lorenstan KJ, Schrospshire LC, Ahn HS. Congenital odontoid aplasia Lorenstan KJ, Schrospshire LC, Ahn HS. Congenital odontoid aplasia and posterior circulation stroke in childhood. and posterior circulation stroke in childhood. Ann NeurolAnn Neurol 1988;23- 1988;23-

410-413410-413

BACKGROUNDBACKGROUND

posterior circulation ischemia has a posterior circulation ischemia has a higher morbidity and mortalityhigher morbidity and mortality

Fifty percent of these patients who Fifty percent of these patients who are managed conservatively are managed conservatively progress to develop infarction progress to develop infarction

BACKGROUNDBACKGROUND

Diagnosing even a percentage of the Diagnosing even a percentage of the patients with VBI as having CVJ patients with VBI as having CVJ anomalies may have major anomalies may have major therapeutic & prognostic therapeutic & prognostic implications.implications.

Aims and ObjectivesAims and Objectives::

Using 99Tc ECD brain SPECT to Using 99Tc ECD brain SPECT to document the presence of posterior document the presence of posterior circulation cerebral ischemia in circulation cerebral ischemia in patients with CVJ anomalies and patients with CVJ anomalies and correlate with symptoms of VBI. correlate with symptoms of VBI.

PROSPECTIVE STUDY DONE OVER PROSPECTIVE STUDY DONE OVER A SIX MONTH PERIODA SIX MONTH PERIOD

STUDY DESIGNSTUDY DESIGN

19 PATIENTS WITH FIXED AAD

Clinical assessment & Brain SPECT on admission

CONTROL GROUP(7 PTS)

VBI GROUP(12 PTS)

TOO + PF TOO + PF

Rpt SPECT at 4 weeks Rpt SPECT at 4 weeks

VBI GROUPVBI GROUPPts with features suggestive of VBI Pts with features suggestive of VBI

(Drop attacks, episodic vertigo, (Drop attacks, episodic vertigo, visual disturbances and dysarthria)visual disturbances and dysarthria)

CONTROL GROUPCONTROL GROUPpatients without symptoms of VBI patients without symptoms of VBI

Operative procedureOperative procedurecombined TOO and Occipito-cervical combined TOO and Occipito-cervical

fusion from occiput to C3, using fusion from occiput to C3, using contoured loop and sublaminar contoured loop and sublaminar wiring with bone graft placement.wiring with bone graft placement.

Both procedures were carried out Both procedures were carried out consecutively in a single sitting.consecutively in a single sitting.

Patients with reducible AAD, Patients with reducible AAD, requiring only occipito-cervical fusion requiring only occipito-cervical fusion were excluded from the study to were excluded from the study to maintain uniformity.maintain uniformity.

Postoperatively the neck was Postoperatively the neck was immobilized using a philadelphia immobilized using a philadelphia collar for a period of three months.collar for a period of three months.

SPECT scanning was done using SPECT scanning was done using 99Tcm-ECD on a dual headed GE 99Tcm-ECD on a dual headed GE 'Varicam' scanner.'Varicam' scanner.

The final data was displayed on a 10 The final data was displayed on a 10 grade color scale and semi grade color scale and semi quantitative analysis performed. quantitative analysis performed.

SPECTSPECT

Regional cerebellar perfusion <10% of Regional cerebellar perfusion <10% of contralateral lobe, or in case of bilateral contralateral lobe, or in case of bilateral involvement, less than 20% of basal gangliainvolvement, less than 20% of basal ganglia

ABNORMAL SPECT ABNORMAL SPECT SCANSCAN

OBSERVATIONSOBSERVATIONS

RadiologyRadiologyAADAAD 1919BIBI 1515Occipitalisation of atlasOccipitalisation of atlas 1414kippel-feil anomalykippel-feil anomaly 99cerebellar infarctscerebellar infarcts 22

(Both in VBI group)(Both in VBI group)

OBSERVATIONSOBSERVATIONS ( (VBI GroupVBI Group))

Clinical featuresClinical featuresVertigo and drop attacksVertigo and drop attacks 1010 IncoordinationIncoordination 88visual symptomsvisual symptoms 44

RESULTSRESULTS

(Preoperative SPECT)(Preoperative SPECT)

Decreased cerebellar perfusion Decreased cerebellar perfusion in 75% (n=9) of the patients in in 75% (n=9) of the patients in the VBI group compared to 14% the VBI group compared to 14% (n=1) in the control group(n=1) in the control group

(p=0.019, fischer exact, 2 tailed).(p=0.019, fischer exact, 2 tailed).

1

9

0

2

4

6

8

10

Control Gp VBI Gp

Number of pts

RESULTSRESULTSFollowing surgery, five patients Following surgery, five patients

(55%) in the symptomatic group and (55%) in the symptomatic group and none in the control group had none in the control group had improvement in cerebellar perfusion.improvement in cerebellar perfusion.

All five patients showing All five patients showing improvement on SPECT also had improvement on SPECT also had improvement in their symptoms of improvement in their symptoms of VBI following surgery VBI following surgery

Two pts in VBI group developed Two pts in VBI group developed meningitis in the postoperative period & meningitis in the postoperative period & had a further decrease in cerebellar had a further decrease in cerebellar perfusion on the follow up SPECT scan.perfusion on the follow up SPECT scan.

Another 2 pts in VBI group had cerebellar Another 2 pts in VBI group had cerebellar infarcts on MRI & did not show infarcts on MRI & did not show improvement in cerebellar hypoperfusion improvement in cerebellar hypoperfusion following surgery.following surgery.

Pathogenesis VBI in CVJ AnomaliesPathogenesis VBI in CVJ Anomalies

Chronic low grade micro-traumaRptd flex/extn of vessel

Chronic low grade micro-traumaRptd flex/extn of vessel

Intimal damageIntimal damage

ThrombosisThrombosis

EmbolisationEmbolisation

Clinical rarity of posterior circulation Clinical rarity of posterior circulation infarcts in CVJ anomalies could be due toinfarcts in CVJ anomalies could be due to::

Duplication of VA and the adequacy of the Duplication of VA and the adequacy of the circulation of Williscirculation of Willis

patients symptomatic for VBI are not patients symptomatic for VBI are not routinely evaluated for CVJ anomalies routinely evaluated for CVJ anomalies which remain undiagnosedwhich remain undiagnosed

In patients with CVJ anomalies In patients with CVJ anomalies currently used imaging modalities currently used imaging modalities such as cervical spine x-rays and CT such as cervical spine x-rays and CT scans are not adequate to evaluate scans are not adequate to evaluate for vertebro-basilar ischemia for vertebro-basilar ischemia

Ours is the only study of its kind Ours is the only study of its kind documenting hypoperfusion in documenting hypoperfusion in posterior circulation territory in posterior circulation territory in patients with CVJ anomalies.patients with CVJ anomalies.

This hypoperfusion may represent a This hypoperfusion may represent a state of chronic VBI, expected in state of chronic VBI, expected in such patients & such patients & MAY BE REVERSIBLEMAY BE REVERSIBLE following surgery. following surgery.

CONCLUSIONSCONCLUSIONS

Our study shows that rigid Our study shows that rigid immobilisation (provided by occipito-immobilisation (provided by occipito-cervical fusion in our patients) by cervical fusion in our patients) by itself may confer protection from VBI itself may confer protection from VBI and direct repair of VA may not be and direct repair of VA may not be necessary necessary

CONCLUSIONCONCLUSIONWe strongly recommend that in We strongly recommend that in

patients of VBI, a high index of patients of VBI, a high index of suspicion should be kept for CVJ suspicion should be kept for CVJ anomalies and x-rays of the cervical anomalies and x-rays of the cervical spine with flexion-extension views be spine with flexion-extension views be done on all patients. done on all patients.

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