dbs for dystonia : stereotactic technique

Department of Neurosurgery, Northwestern University

DBS for Dystonia:Stereotactic Technique

Joshua M. Rosenow, MD, FAANS, FACSDirector, Functional NeurosurgeryAssociate Professor of Neurosurgery, Neurology and

Physical Medicine and RehabilitationNorthwestern Memorial Hospital


Disclosures

I have no relationship, financial or otherwise, relevant to this presentation

I do surgery for dystonia and feel that it is very effective for the appropriate patients

I am very nervous about the Yankees 2013 season (Although Arod’s hip surgery will increase their OPS through June)


Dystonia Surgery 1641 – Minnius sections the sternocleidomastoid muscle in a

patient with cervical dystonia

1891 – Keen performs first selective rhizotomy for cervical dystonia

1924 – McKenzie performs sectioning of both anterior and posterior spinal roots as well as spinal accessory nerve

1930 – Dandy performs first selective sectioning of spinal roots for cervical dystonia


Dystonia Surgery 1940 – Myers – destructive procedures in the basal

ganglia alleviate tremor

1950 – Spiegel and Wycis – adapt their stereotactic frame for pallidothalamotomies for chorea

1960s – Thalamotomies and Pallidotomies for dystonia


Dystonia Surgery 1960s - Cooper begins performing cerebellar stimulation

for dystonia and other movement disorders and epilepsy

1991 – Intrathecal baclofen infusion

1999 – Kumar – pallidal stimulation in single patient for primary dystonia

1999 - Krauss - pallidal stimulation for cervical dystonia


DBS History - 1971

Harry Benson suffers from painful, violence-inducing seizures. In an effort to alleviate this problem, Benson undergoes an experimental medical procedure, Stage 3, in which electrodes are attached to his brain's trouble spots -- if all goes well, timed jolts of electricity will correct his disability. But when Benson learns to turn up the juice whenever he pleases, his murderous rampage begins.


DBS for Dystonia: FDA Approval

2003 – HDE – Humanitarian Device Exemption granted

Approved for primary dystonia only GPi or STN DBS

Requires IRB approval but is not research


Severe, disabling symptoms from primary dystonia

Should have failed several modalities of treatment

Inadequate response or unacceptable side effects

Good support system

No medical contraindications

No significant untreated depression or anxiety

No significant cognitive deficits

Dystonia DBS: Candidates


Gpi Targeting1. T1 inversion recovery (IR)

sequences very useful do delineate GPI borders

2. Anatomic GPI targetRelative to intercommissural line 18-22 mm lateral 2-3 mm anterior 4 mm inferior

3. Trajectory AP Angle ~600

Coronal angle 0-50


Gpi Targeting

Putamen

Anterior commissure

PallidumAnother method of choosing/verifying anatomic target is to start over lateral border of optic tract and set target just above that


•Start at anatomic target•Want to record at least 6-7mm Gpi

•Good kinesthetic activity

•Determine posterior border •Move posteriorly in 3 mm increments per MER track until internal capsule is reached (as determined by microstimulation-evoked contractions)

•Determine ventral border•Obtain evoked potentials from optic tract

•Final positioning of DBS electrode tip: • at least 2 mm dorsal to OT• at least 4 mm anterior to capsular border

Gpi MER


•Compared to Gpi in PD, Gpi in dystonia:

•has lower neuronal firing rate

•is characterized by less distinction between GPe and Gpi in terms of MER characteristics, making the transition determination more challenging

Gpi MER


GPi


Frame Placement


Striatum Sparse Cells Firing Rates: 0.1Hz to

50Hz Low Amplitude


GPe

Denser Cellularity Spontaneous

Background Activity Two Distinct Cellular

Patterns Pauser Cells Burster Cells


Pauser Cells

Irregular firing pattern Frequency: 30-200 Hz Moderate to high

amplitude


Burster Cell

Cluster rate slow (10-20 Hz)

Burst Frequency high (> 500 Hz)

Medium to high amplitude


Border Cells

Firing rates 10-40 Hz Large amplitudes No movement initiated

responses


GPi

Dense Cellularity Spontaneous Background

Activity Two Distinct Cellular

Patterns Tremor Cells High Frequency Cells

Kinesthetic Responses


High Frequency Cells

Frequency: 50-300 Hz Kinesthetic responses Large Amplitudes


Pallidal MER

Optic

GPi

Laminae

Laminae

GPe

Putamen


Physiologic Verification Intraoperative test stimulation

Clinical benefits - NONE

Side effects • Muscle contractions too close to IC• Flashing lights – too close to OT• Slurred speech – too close to IC


Programming

• Begin 4 weeks after surgery

• Effects may not be seen for days


DBS for Dystonia

Surgical selection needs refinement Primary dystonia does best

Multiple targets have been tried over the years GPi, STN, Voa, Vop

Intraoperative physiology differs from PD Programming more complex

Higher current than PD Delays to improvement

While prospective studies are emerging, more are needed to refine the procedure


DBS: Risks

Not everyone experiences the same amount of improvement Inability to guarantee a certain level of improvement

Stimulation-related side effects Infection – 5% per side Hardware breakage

Rare in general but higher in dystonia patients due to abnormal movements (esp. cervical dystonia)

Bleeding – 1-3% Anesthesia risks


E-mail: [email protected]

Thank you for coming!

dbs for dystonia : stereotactic technique

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