RF
- Dynamic impedance
- Observe for “stun effect”
- Stimulation - RF electrode
- Observe effect on:
- Tremor
- Movement
- Sensory phenomena
- Speech
- Eye movements
- Lesion settings:
- 70°C for 40s
- Bilateral lesion be careful and do them 6 months apart
- Indications
- 48° will cause swelling without lesion
- Movement disorders:
- Thalamotomy (VIM, VOP, VOA)
- Pallidotomy
- Pallido-tractotomy
- Psychiatric:
- Capsulotomy
- Cingulotomy
- Pain:
- Thalamotomy (CM / CL)
- Cingulotomy
- Outcome
- Reference:
HiFUS
- 1028 tiny Ultrasonic emitters in half sphere
- MRI guided, NOT non-invasive, incisionless, outpatient
- Awake patient, head shave, stx frame,
- Can only target deep areas, close to midline
- Insightec Inc, FDA approved 2017
- Approved indications: Essential Tremor, PD tremor/dyskinesias, (pain)
- New indications: subthalamotomies for PD patients
- MR-guided focused ultrasound
- Real-time temperature change monitoring with MRI
- Sonication → temp check → location check → correction if necessary → neurology check → sonication
- Images
Lesional surgery
- Lesional procedures using radiofrequency ablation have been largely replaced by DBS due to its greater safety and its reversibility,
- Types
- Pallidotomy
- Thalamotomy
- Subthalamotomy
- Indication
- Resource limited setting where
- DBS may not be economically feasible
- Clinical follow- up might be a challenge
- Chronic infection complicating past DBS,
- Metal allergies,
- Risk to implanted DBS hardware from falls or obsessive- compulsive head banging
- Palliative procedures if limited lifespan
- Cingulotomy for cancer pain
- Pallidotomy in severe advanced Parkinson’s disease.
- Procedure
- Radiofrequency thermocoagulation of brain tissue
- With an electrical lesion generator
- Most commonly performed but requires a burr hole and passage of a rigid probe through the brain to the target to be lesioned.
- Non- invasive lesioning modalities
- Gamma knife radiosurgery that has the disadvantage of several months for onset of efficacy
- Magnetic resonance– guided high frequency focused ultrasound for which there is promising initial clinical evidence
- Lesional surgery for psychiatric disorders
Procedure | Description | Indications |
Anterior capsulotomy | Thermal damage or gamma knife surgery to target fibers connecting the ventromedial cortex, orbitofrontal cortex, and anterior cingulate gyrus with the thalamus, amygdala, and hippocampus. These fibers pass through the anterior one-third of the anterior limb of the internal capsule | Indications for anterior capsulotomy vary across Europe. In Sweden, it is used for generalized anxiety disorder, agoraphobia with panic disorder, and obsessive-compulsive disorder, whereas in the UK it is mainly used for depression and obsessive-compulsive disorder |
Anterior cingulotomy | Targets are the supracallosal fibers of the cingulum bundle (part of the Papez circuit) as it travels through the anterior cingulate gyrus. The lesion procedure also results in damage to a localized area of anterior cingulate cortex. The target site for the lesion is 20-25 mm posterior to the anterior horn of the lateral ventricles, 7 mm from the midline and 2-3 mm above corpus callosum | Initially developed for the treatment of intractable pain, but its other indications include anxiety disorders, depressive disorders, and obsessive-compulsive disorder |
Limbic leucotomy | The fibers targeted are those of the anterior cingulate cortex, the cingulum bundle, and frontostriatolimbic circuits. It is a combination of anterior cingulotomy and stereotactic subcaudate tractotomy, although the frontal lesions are slightly smaller than those conventionally created using stereotactic subcaudate tractotomy | Its main indications are for depression, obsessive-compulsive disorder, and anxiety disorder. Used as a treatment alternative where anterior cingulotomy has resulted in non-sustained or partial benefit |
Stereotactic subcaudate tractotomy | Division of fibers connecting the orbital cortex to subcortical and limbic areas (e.g., thalamus, basal ganglia, amygdala). Lesions are placed in the white matter of the substantia innominata, below the head of the caudate nucleus. Typically, the lesions would be created using radioactive yttrium-90 rods inserted using stereotactic guidance | This procedure has been used to treat depression, obsessive-compulsive disorder, anxiety disorder, and chronic pain, although it is no longer offered within the UK |
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