WHAT HAPPENS IN DBS SURGERY?
Several hours prior to the start of surgery you will check in to the presurgical area. Your medication list will be reviewed. It is important to have accurate dosages and timing of your medication so that you will get your typical regimen during the hospital stay. PLEASE MAKE SURE YOU BRING ALL YOUR PARKINSON’S MEDICATIONS WITH YOU TO THE HOSPITAL. You should skip your morning doses of Parkinson’s medications, but you should take your blood pressure and other medicines. Although being in an off state is more uncomfortable for many patients it is better than having severe dyskinesia that would pull you off the operating table.
You will change into a hospital gown. A nurse will place an I.V. usually in your hand/arm. The anesthesiologist and their assistants will meet you and discuss your operative care. The surgeon will meet with you and your family, and answer any questions you have. The location of surgery is marked on the skin.
Halo Placement
The halo is a ring that is attached to your skull with four pins. It forms the attachment of equipment used in during surgery to guide the electrodes in the brain. Local anesthetic is injected into the skin so that you won’t feel the pins. Some patients describe “tightness” when the pins are placed that fades.
CT scan / MRI scan
A CT scan, or possibly and MRI scan is obtained. Rods are attached to the halo to pick the target in the brain to place the DBS electrodes. This helps us to directly target the location in which to place the electrodes.
Positioning in operating room
When you come into the operating room the halo on your head is attached to the operating room table. It becomes your pillow. The table is comfortable. A bladder catheter will be placed. You will be lying on your back in this position for several hours. Some patients complain of back pain after a while. This can be treated with pain medications. Over your head is an x-ray machine. Once you are positioned your head is scrubbed clean and sterilized, then drapes separate your face from the surgeon.
Sedation
It is valuable for you to be awake and cooperative, and to see your Parkinson’s symptoms during parts of the surgery. During other times you are lightly sedated. You will be breathing on your own and in a deep sleep
Burr Hole placement
For each DBS electrode a burr hole is drilled in the skull. It is located just behind the hairline on each side, several centimeters from the midline of the skull. A power drill is used with a bit that stops automatically when the inside of the skull is reached. The hole is about the size of a nickel. It is covered with a plastic cap system, called the Navigus Cap that secures the electrode to the skull. It also sticks up above the surface of the skull about 3 mm. Patients without hair can see this bulge when all the incisions have healed.
Microelectrode mapping
Microelectrode recording uses a small wire microphone to listen to the activity of neurons in the brain. Different parts of the brain have different patterns of neuronal activity. For instance, the subthalamic nucleus has many active neurons.
The microelectrode is slowly moved through the brain tissue above and below the planned surgical target. The findings of this recording verify and refine the location for implantation of the DBS electrode. This portion of the surgery can take an hour or more.
Macrostimulation Testing
When the surgical target has been verified the DBS electrode is inserted into the brain. You won’t be able to feel this. In fact, you can’t feel anything inside the brain. But sometimes your tremor or rigidity is improved by just inserting the electrode.
The DBS electrode is attached to an external stimulator. Then the effect of stimulation on your symptoms of Parkinson’s disease is tested. The stimulation intensity is increased higher than normal to look for side effects. You may detect a tingling sensation in your hand, face, or leg. Your eyes might deviate to one side.
Macrostimulation verifies that the electrode is in a satisfactory position. You may feel dizzy or light-headed, or tingling.
Closing the incision
When the surgery is completed the electrodes are coiled up under the scalp. The incisions are sutured closed. Then the pins and halo are removed.
Recovery room
You are monitored in the recovery room for an hour or so before you see your family in your hospital room.
Postoperative Hospital Care
You will spend at least one night in the hospital after the surgery. This may be in the intensive care unit, or the step down care unit. The nurses will be watching your blood pressure, and checking your neurological exam to look for problems.
The management of your Parkinson’s medications can be challenging in the hospital because of the multitude of medicines that are often taken frequently. In addition, your response to Parkinson’s disease is altered by surgery, and you have skipped some doses during surgery. This problem needs careful attention from your nurse and doctor.
Most patients feel well enough to go home (or to a hotel if they are from out of town) the next morning after surgery. Prior to discharge you need to be able to walk as you did before surgery, eat without vomiting, have your pain controlled with oral pain medications, and be able to use the restroom. You will be evaluated by a physical therapist before discharge.
Technology in DBS
Brain Stereotaxis
Specialized equipment has been developed that can precisely guide probes into the brain. This is called brain stereotaxis. The equipment is called the stereotactic halo and arc system. The ring is attached to the skull using pins so that is cannot move. The ring forms a coordinate system (x,y,z).
The arc system attaches to the ring in the operating room. The coordinates (x,y,z) for the location in the brain are dialed into the mechanical system in the arc. This guides the electrode from any point on the surface of your head to the target site. The system has submillimeter accuracy.
Computerized Stereotactic Navigation
Computer software has revolutionized the ability to combine different images and measure target coordinates for surgery. The Medtronics Framelink software is the main software for targeting in DBS surgery. Your preoperative images including MRI and/or CT scans are downloaded into this software. The position of the fiducial markers are captured by the computer. This sets up the x,y,z coordinate system in your brain.
Important landmarks in your brain are measured in this software including the anterior commissure and posterior commissure. The location of the surgical targets is measured from these points.
Microelectrode Mapping
Your brain contains billions of neurons. These are the cells that communicate in your brain. They used electrical signals to talk to each other called action potentials. This is a small electrical signal.
Microelectrode recording is a technology that lets us listen to the action potentials of the individual neurons in your brain. The system used a small needle tip wire which acts like an electrical microphone. It is connected to electrical amplifiers. The signals are processed on a computer and played on a speaker.
Microelectrode recordings sound like popcorn popping, or buzzing static noise. Different regions of the brain have different typical sounds. Microelectrode mapping is the process of moving a microelectrode through the brain tissue, listening to neurons, and marking where the edges of different brain structures are.
Microelectrode mapping helps to refine and confirm the location for implantation of a DBS electrode. It is a valuable tool of the neurosurgeon during surgery.