intratechal baclofen therapy

7/28/2019 Intratechal Baclofen Therapy

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INTRATHECAL

BACLOFEN THERAPY


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SPASTICITY

Defined as a velocity-dependent resistance to

passive movement of a joint and its associated

musculature

Characterized by hyper excitability of the stretch

reflex related to the loss of inhibition from

descending supraspinal structure


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Must only be treated when excess tone leads

to functional losses, impairment of

locomotion, or deformities

Surgical procedures must be performed so

that excess of tone be reduced without

suppressing useful muscular tone or impairing

any residual motor/sensory functions.


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Managing spasticity


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Mechanism of action of main pharmacological anti-spastic treatments.


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Baclofen

Binds to GABA-B receptors that are found

throughout the neuroaxis

Most of its action occurs at the presynaptic

terminals, decreasing calcium influx and

consequently reducing neurotransmitter

release

Main adverse effects of oral baclofen :

sedation or somnolence, excessive weakness.


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TECHNICAL NOTE


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HISTORY

1985

Pump implanted

subcutaneously

associated with poor

healing and wound

dehiscence

1998

Grabb & Pittman

Subfascial technique

lowering the risk of skin dehiscence


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Patient Positioning

Left decubitus position with flexed hips and

knees

A soft pillow is placed under the hips and

between the knees to avoid pressure sores

Upper arm is held away from the surgical field


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Surgical preparation

Antibiotics are administered at the time of

anesthesia induction

Operating field is prepared with chlorhexidine

and adhesive sterile draping


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Implant Site Selection

The preferred surgical side is the right (for

right handed)

A transverse skin incision is made in the right

hypocondrium at the level of the upper third

of line running between the xyphoid process

and pubic ramus

Avoid contact with the lower end of the rig

cage


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Dissection

Incision is deepenedthrough the subcutaneousfat

Care is made not to

dissect it from the musclefascia to avoid creatingdead space

A single plane is created

down to the rectussheath, and both thelateral and medial edgesof the rectus abdominisare identified.


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The fascia of the

rectus sheath is incised

horizontally and is

continued laterallyinto the full thickness

of the external oblique

muscle.


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At the medial side of the wound, the anteriorlayer of the fascia of the internal oblique musclemerges with its posterior fascial layer over the

lateral edge of the rectus abdominis muscle at avariable distance along the line of lineasemilunaris

Cutting in between these internal oblique layers

help to open a natural plane between theexternal oblique muscle anteriorly and theinternal oblique, transversus abdominis, andperitoneum posteriorly.


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In summary, a space is created starting

beneath the anterior rectus sheath medially,

continuing laterally under the externaloblique.

The internal oblique, the transversus

abdominis, and the peritoneum constitute theposterior wall of this pouch


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Checks

Pump will fit inside the pouch

Fascia will close easily over the entire pump

and connector

There is sufficient place to connect the

catheter

No bleeding


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Spinal Acces

Level of insertion: L3-4

Skin is incised 2 cm over the lumbar spine

down to the supraspinous fascia in the

interspinous space

A 14-gauge Tuohy needle is used to access the

thecal sac


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Spinal Access

The entry point is made 1-1.5 cm from themidline away from the interspinous ligamentto avoid fracture of the catheher after

insertion Do not enter too laterally beyond the pedicle

to avoid catheter migration as the thin fasciallayer and increased muscle bulk laterally couldpotentially increase the differential motionand lead to migration of the catheter


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Tunneling

Tunneling is performed from subfascial pouch

in the abdomen and is directed to the lumbar

incision

Tunneling device leaves the pump side from

inside the subfascial pouch by passing

between the muscle layer and its fascia to end

up in the subcutaneous tissue


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Tunneling

Before attaching the catheter to the pump

connector, make a check that CSF is draining

and the catheter is secured with the

connector with silk ties

The full length of the catheter is left without

shortening and remaining tube is coiled

behind the pump and over the lumbar fascia


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Postoperative Course

Stay in the hospital for at least 48 hours to

make sure there is no wound leak or

postlumbar puncture syndrome


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Operation Duration

Varies between 50 and 150 minutes, with an

average of 70 minutes


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Pump

Photographic (A) and radiographic (B) representations of the SynchroMed model EL intrathecal

baclofen pump depicting the pump rotor (red ring), reservoir port (yellow arrow ), catheter-

access port (blue arrow), and the pump connector (magenta arrow).


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Outcome


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Complication


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Baclofen Dose

The average dose of intrathecal baclofenstarted at 200 mcg a day and increased overtime for the first year or two and then

stabilized below 400 mcg a day. the amount of baclofen infused usually has to be

increased in the first 612 months. In mostpatients, it stabilizes by a year to 2 years and

further increases in dosage are not necessary. The range of effective dosing is quite large. Some

patients are well controlled with 25 mcg per dayand other patients may need over 1000 mcg a day


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Baclofen Withdrawal Syndrome

MH: Malignant

Hyperthermia

NMS: Neuroleptic Malignant

Syndrome


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intratechal baclofen therapy

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