Neuromodulation for chronic intractable primary headache Laurence Watkins

Neuromodulation for chronic intractable primary headache Laurence Watkins Victor Horsley Department of Neurosurgery National Hospital for Neurology & Neurosurgery BASH Hull January 2011

Neuromodulation in primary headache disorders n Peripheral neuromodulation u n Occipital nerve stimulation Central neuromodulation u Deep Brain Stimulation

n n Why? Results Procedure Future

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

Statistical parametric map (SPM{F}) showing brain regions in which r. CBF correlates (positively or negatively) with pain scores, in particular the dorsal rostral pons, ACC and cuneus (voxels significant at P Matharu, M. S. et al. Brain 2004 127: 220 -230; doi: 10. 1093/brain/awh 022 Copyright restrictions may apply.

Graphs showing (A) mean pain scores and (B) mean scores of stimulator-induced paraesthesia by scanning states Matharu, M. S. et al. Brain 2004 127: 220 -230; doi: 10. 1093/brain/awh 022 Copyright restrictions may apply.

Cervico-trigeminalhypothalamic system

Results of ONS in cluster headache n 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 n n n Median 12 years since onset Median 6 years since became chronic Median age 46 years (32 -58)

Median follow up 20 months n=8 n 2 patients substantial improvement « n 3 patients moderate improvement « n n n 40 -80% reduction 1 patient mild improvement « n 90 -95% reduction 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 n n n 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 n n n 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 n Known risks: u u u u n 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 n n 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 n Insertion of electrodes « LA n + Sedation Test stimulation of electrodes « Awake n Insertion of battery and tunnelling of leads « Asleep n n (GA with LMA) Alternatively GA throughout if difficult airway or reflux USA: 2 stage procedure

Skin marking n n n Awake, sitting upright on stool Midline Intermastoid line Spinous process of C 1 3 cm from midline Chosen position of battery

Positioning n n Lateral position Access to all operative areas Strict aseptic technique to establish field Anaesthetist access to patient for communication and airway

Test stimulation n n Radiating occipital paraesthesiae bilaterally 300 microseconds pulse width 60 -80 Hz At low amplitude – typically 1 -2 V If no paraesthesiae or if amplitude >4 V then reposition electrode

2 -3 days later n n n n 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 10 m

Real Life n n 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 n n 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 n n Single electrode on 3 cm rechargeable “capsule” Unilateral Need to map position of nerve with subcutaneous needle electrode Then place bion at optimal point

Experience with bion n n Implanted 10 All unilateral syndromes 6 hemicrania continua 5/6 benefit Faster onset of benefit (approx 2 weeks) cf cluster (months)

Limitations of bion n n 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 n n No wires to tunnel Thus can be done with local anaesthetic only Shorter operation No migration because no wires causing tension

Next Steps n n n n 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-trigeminalhypothalamic system

Neuromodulation in primary headache disorders n Peripheral neuromodulation u n Occipital nerve stimulation Central neuromodulation u Deep Brain Stimulation

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

Thank you laurence. watkins@uclh. nhs. uk