This protocol is used to monitor the rehabilitation of patients with hand grip deficits. Chronic stroke patients and those with other neurological diseases involving motor deficits may benefit from this technique. Magnetic Resonance Imaging allows monitoring of the adaptability of the brain.
In other words, neuroplasticity in response to rehabilitation of grip performance. With suitable modification of the force stimulus device this method can be applied for rehabilitation of disabilities affecting other regions of the body. This device, and any modifications, must retain MR compatibility.
It's important to insure that the MRI rod has been properly connected and it's functions verified before bringing a subject into the MR room. Prior to starting this experiment first obtain informed consent from the subject and thoroughly screen them for MRI safety. Do not proceed with the scan if the participant has any potential MRI contraindications.
To begin setup, first bring the magnetic resonance compatible hand induced robotic device into the MRI room and place it near the penetration panel. Then, insert the 3/8 inch pneumatic tube into the pass through tube in the panel, into the adjacent MRI support room. Then, connect the support room fore sensing and encoder cables to the D-sub connector on the external side of the penetration panel as shown here.
Connect the 3/8 inch pneumatic tube fitting, emerging from the penetration panel, to the outlet of the interface power unit pressure regulator outlet. Then, connect the four millimeter pneumatic tube to the outlet of the compressor in the inlet of the air filter on the interface power regulator. After extending and lowering the scanner bed attach the bottom half of the head coil and have the volunteer lay down, making sure that they are resting comfortably with their arms extended and use small foam pads to immobilize the participant's head.
Attach the communication ball on the volunteer's chest and provide instructions on its use. Also, attach the top of the head coil. Now, loosely install the robotic device on the side of the patient opposite to their brain lesion using the corresponding bed slot.
Then, with the volunteer's elbow resting on the table to support their arm, move the device handle to the webbing between thumb and forefinger and help them grab the handles. If the device is on the opposite side of the table from the penetration panel position the cables in the pneumatic tube so that they pass under the table rather than over the patient. Next, instruct the volunteer to squeeze and push or pull the device until they have the most comfortable position for squeezing.
Then secure the device firmly in place by tightening the plastic nuts using an MR compatible wrench. Now, run the custom user interface stimulus program. Set the pressure to the minimal set-up level to automatically push the handle to the end stop, verifying display of motion and force waveforms.
Next, set the force level and instruct the volunteer to completely squeeze two to three times for approximately two seconds. Observe whether the volunteer can complete a squeeze at that force level. Gradually increase the force level and repeat squeeze attempts until they cannot complete a squeeze.
This measurement serves as the volunteer's maximum grip strength. The program will automatically calculate 60%40%and 20%of the maximum force level for use during testing. Next, confirm that the communication ball works, then position using the laser alignment, before moving the table and the participant into the scanner's iso center.
Now, using the user interface, generate the instruction and stimulus images and set the system to apply the first force level and wait for a trigger signal from the MRI scanner. The program will display a set of instructions to remind the volunteer how to respond to the visual stimulus. The program will wait for the scanner to provide a trigger signal then remove the instructions and show a fixation cross that the volunteer should focus on.
When the fMRI scan acquisition begins a visual metronome will be displayed in the form of a growing and shrinking circle. The volunteer should completely squeeze and release the handle synchronously with the stimulus. Rest periods will separate stimulus periods during which time the fixation cross will again be displayed.
Observe the live plots of force and displacement to monitor the force output and participant task performance. Once the experiment is complete let the participant know they can relax and to let go of the handle. Finally, collect a series of anatomical scans.
This figure shows typical motor task results. Here we see fMRI activations superimposed on a brain outline and as pseudo-color on a three dimensional, cross-sectional view of the volunteer's anatomical image. M1 indicates the primary motor cortex and SMA indicates the supplementary motor area.
This image shows pseudo-color activations rendered on a brain template. This graph shows actual force output measured in units of force as a function of time. The output was recorded in real time.
The white bar corresponds with the 60-second stimulus and rest period. Here, a single voxal time course of activation is shown, chosen from a voxal at the somatosensory area at the location of the cross-hairs in this image. All subjects must be properly trained in performing the metronome tracking grip motions in advance.
In addition, synchronization between the visual stimulus and the MRI sequence is crucial. Additional imaging modalities can be used in this protocol, including Diffusion Tensor Imaging to detect white matter fiber tract orientation and growth, which is also expected to change with rehabilitation. Performing any MR experiment is hazardous due to the powerful magnetic field generated by the scanner.
Therefore, all subjects and experimenters must follow MR safety guidelines including screening for contraindications. Development of this process will allow the demonstration that stroke recovery continues beyond six months post-injury suggesting that therapy and associated insurance reimbursement should continue beyond this time.
