neuromodulation for chronic intractable primary headache laurence watkins victor horsley department...

Neuromodulation for chronic intractableprimary headache

Laurence WatkinsVictor Horsley Department of NeurosurgeryNational Hospital for Neurology & Neurosurgery

BASH Hull January 2011

Neuromodulation in primaryheadache disorders

Peripheral neuromodulation Occipital nerve stimulation

Central neuromodulation Deep Brain Stimulation

Why? Results Procedure Future

Occipital headaches

Weiner 1995: ONS in patients who had responded to repeated GON injection

Copyright restrictions may apply.

Matharu, M. S. et al. Brain 2004 127:220-230; doi:10.1093/brain/awh022

Statistical parametric map (SPM{F}) showing brain regions in which rCBF correlates (positively or negatively) with pain scores, in particular the dorsal rostral pons, ACC and cuneus (voxels

significant at P

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Matharu, M. S. et al. Brain 2004 127:220-230; doi:10.1093/brain/awh022

Graphs showing (A) mean pain scores and (B) mean scores of stimulator-induced paraesthesia by scanning states

Cervico-trigeminal-hypothalamic system

Results of ONS in cluster headache Burns B; Watkins L; Goadsby P.

Lancet 2007 369:1099-1106 Treatment of medically intractable cluster headache by occipital nerve stimulation: long term follow up of eight patients

8 patients with chronic cluster headache Median 12 years since onset Median 6 years since became

chronic Median age 46 years (32-58)

Median follow up 20 months n=8

2 patients substantial improvement 90-95% reduction

3 patients moderate improvement 40-80% reduction

1 patient mild improvement 25% reduction

6 said they would “recommend it to other CCH patients”

1 stopped triptan use and 2 reduced 2 patients no improvement

First Meeting

Check have been fully assessed in Headache Neurology Clinic (chronic, disabling, intractable)

General fitness & airway satisfactory; reflux?

MRI ? (because can’t have MRI once ONS is implanted)

Any major surgery planned ? (because restriction of monopolar diathermy once ONS implanted)

Explaining procedure

Discussion with patient

Describing the procedure Relatively novel operation – NICE

assessment “in progress” 200+ patients so far in our unit since

2002. Now about 1 per week. Known risks: next slide Clearance from PCT

Discussion with patient

Known risks: may not help infection requiring removal of implant electrode migration neck stiffness breakage or failure of components tethering to skin or muscle skin erosion early depletion of battery

Clearance from PCT

Follow up clinics

Typically 4 in first year Joint assessment with Headache

Neurologist and Specialist Nurse (usually on day care unit)

Gradually refine the settings to get best response (headache diary), without patient discomfort

Checking for any problems

Stages of the operation

Insertion of electrodes LA + Sedation

Test stimulation of electrodes Awake

Insertion of battery and tunnelling of leads

Asleep (GA with LMA) Alternatively GA throughout if difficult

airway or reflux USA: 2 stage procedure

Skin marking

Awake, sitting upright on stool Midline Intermastoid line Spinous process of C1 3cm from midline Chosen position of battery

Positioning

Lateral position Access to all operative areas Strict aseptic technique to

establish field Anaesthetist access to patient for

communication and airway

Test stimulation

Radiating occipital paraesthesiae bilaterally

300 microseconds pulse width 60-80 Hz At low amplitude – typically 1-2V If no paraesthesiae or if amplitude

>4V then reposition electrode

2-3 days later Activate implant Set initial parameters Pleasant radiating occipital paraesthesiae

bilaterally Patient education to use handset for continuous

comfortable stimulation Patient given implant ID card Advised to restrict strenuous activity in first 8

weeks Drive when comfortable, but switch implant off

while driving Restrictions after 2 months: no MRI, scuba

diving below 10m

Real Life

Some dramatic results but have to give realistic expectation to patients. Approximately 70% will be pleased with result and 30% disappointed.

Relatively low risk; so may be justifiable in cases where chronic headache is disrupting quality of life and intractable to medical treatment

Main technical challenges

Placing electrodes to get paraesthesiae Anchoring/looping the electrodes Minimising infection risk Not “instant” result so can’t really do “trial

electrodes”

Experience with bion

Single electrode on 3cm rechargeable “capsule”

Unilateral Need to map position of nerve with

subcutaneous needle electrode Then place bion at optimal point

Experience with bion

Implanted 10 All unilateral syndromes 6 hemicrania continua 5/6 benefit Faster onset of benefit (approx 2

weeks) cf cluster (months)

Limitations of bion

Unilateral Thus not ideal for chronic migraine

and cluster Single electrode Thus need nerve mapping and

precise placement Frequent recharging (daily or in

some patients several times per day)

Advantages of bion

No wires to tunnel Thus can be done with local

anaesthetic only Shorter operation No migration because no wires

causing tension

Next Steps RESPONSE trial of ONS in chronic

migraine (large, multicentre, randomised controlled trial)

CE marking & NICE assessment Rechargeable stimulators Smaller stimulators More experience Interplay between medication and

neuromodulation Other inputs into CTH system

Cervico-trigeminal-hypothalamic system

Neuromodulation in primaryheadache disorders

Peripheral neuromodulation Occipital nerve stimulation

Central neuromodulation Deep Brain Stimulation

Conclusions

Consider in patients with chronic, disabling, intractable primary headache

ONS and DBS are both “low risk” when practiced in a multidisciplinary team and in experienced hands (but the rare complications in DBS can be severe)

Conclusions

May be logical to see ONS as primary surgery and reserve DBS for those who don’t respond or can’t have ONS

Thank youlaurence.watkins@uclh.nhs.uk