Test period
Position and anatomical landmarks
The patient is placed on one side in a forward flexed position. The procedure can also be performed in a sitting position. The catheter is placed under local anaesthesia.
Using fluoroscopy, a Tuohy needle is inserted paramedially at an angle of 45° in the interlaminar space. After placement in the subarachnoidal space, the stylet is removed. The catheter is introduced through the needle until its tip is at the desired spinal cord level relevant to the patient's pain. For pain in the L5-S1 dermatome, the tip of the catheter should be placed at level Th11.
Procedure
When an adequate amount of cerebrospinal fluid has flowed from the catheter, a small incision is made around the needle to the muscle fascia. The catheter is fixated and tunnelled cranially above the 10th or 11th rib. Thereafter, the gate system is connected to the catheter and placed in a subcutaneous pocket.
Finally, through percutaneous puncturing of the gate system, the system is connected to an external pump.
Complications
- Post-puncture headache.
- Infection in the system.
- Dislocation or leakage of the catheter.
Implant of an electronic medication pump system
After a positive test period, a decision is made (together with patient) to implant an electronic and programmable pump system.
After removal of the gate system, a subcutaneous pocket is made on the same in the abdomen wall in order to implant the pump. The already existing catheter is tunnelled to this pocket.
The pump is filled with the desired medication and connected to the catheter. The pump system is programmed, the daily dose estimated, and the first volume administered to fill the dead space of the pump system and the catheter.
Complications
- Postpuncture headache.
- Infection in the system.
- Dislocation, breaking or leakage of the catheter.
- Fluid collection around the pump (seroma).
- Granuloma at the tip of the catheter with the risk of neurological complications.
- Software problems in the pump system.