Intrathecal Baclofen Therapy

169 Intrathecal Baclofen Therapy
Richard C. E. Anderson

♦ Preoperative

Patient Evaluation

Intrathecal baclofen (ITB) trial to assess response of spasticity or dystonia to test dose of baclofen delivered through lumbar puncture
Neurologic evaluation: screening clinical criteria for appropriateness of therapy; can assist with determining extent of ITB therapy
Physiotherapy evaluation: assist with screening assessment for spasticity; establish goals for post-ITB implantation

Review Imaging

Presence of fusion mass, scoliosis, or other structural abnormalities may change the level of access to the intrathecal space

Special Equipment

SynchroMed II implantable pump (Medtronic) for pediatric patients (20 or 40 mL capacity)
Catheter with graded markings
14-gauge Tuohy needle
Catheter passer/sheath
Fluoroscopic x-ray machine

Anesthetic Issues

General anesthesia

♦ Intraoperative

Positioning

Patient in the left lateral decubitus position

Most surgeons are right handed
A significant number of patients have left upper quadrant gastrostomy tubes
Use of a vacuum bean bag or tape can assist with maintenance of lateral position

Subcutaneous pocket

Epidermis is opened with a 8 cm horizontal incision approximately one fingerbreadth beneath the right costal margin
Use needle tip electrocautery for opening subcutaneous tissue and fascia
Fascia is opened between the external oblique muscle laterally and the abdominus rectus muscle medially to create a subfacial pocket.

Placement of intrathecal catheter (lumbar)

Vertical skin incision at approximately at L4–L5 with dissection to level of lumbar fascia (Fig. 169.1A)
Tuohy needle inserted 5 mm lateral to midline and directed obliquely one or two levels cephalad to access the intrathecal space (Fig. 169.1BA)
Fluoroscopy is useful to direct the trajectory of the needle and to avoid multiple dural punctures
The catheter is then placed at the appropriate level under fluoroscopic guidance.
- T10–T12 catheter tip position is used for spastic diplegia
- T1–T2 position for spastic tetraparesis
- C1–C2 for generalized secondary dystonia
A pursestring suture is inserted into the fascia around the Tuohy needle, the needle and then the guidewire are removed, and the pursestring suture is tightened
The catheter is secured with a nonabsorbable suture and silastic butterfly flap (Fig. 169.1B)
Catheter placement in patients with fused spines requires preoperative planning. There are three possible techniques to address fusion.
- If there is an open interspace within the lumbar spine, placement can be done as described using fluoroscopic guidance.
- If the entire lumbar spine is fused, a hole in the fusion mass can be drilled, the catheter placed through the dura at the opening, and passed to the appropriate level.
- A cervical approach can be done through a 4 to 5 cm midline incision and limited laminectomy. The catheter is passed through a small dural opening and closed with a pursestring. The catheter tip is then advanced with fluoroscopy to the appropriate level.
Tunneling and connection to subcutaneous pump
Using a curved passer, the catheter tubing is tunneled anteriorly to the sub-fascial pocket.
Cerebrospinal fluid (CSF) should be withdrawn from the end of the catheter after tunneling and ease of flow should be confirmed before attaching it to the pump.
The catheter is then connected to the pump and secured with a nonabsorbable suture.
The pump is then secured with nonabsorbable sutures within the pocket.

Wound Closure

Pulse irrigation of wounds with saline solution; antibiotics or 100 ppm of iodine can be used if desired. Absorbable sutures for fascia and subcutaneous tissues, followed by Steri-Strips.