Intrathecal Baclofen Therapy for Spasticity by t8929128

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									                                                                                                                                                          Neurosurgery


Intrathecal Baclofen Therapy for Spasticity

S
      pasticity is defined as a motor disorder characterised        following resolution of spasticity. Patients on anticoagu-
      by a velocity-dependent increase in tonic stretch             lant medication should have this stopped temporarily
      reflexes (muscle tone) with exaggerated tendon jerks          during the intrathecal baclofen trial and for the subse-
resulting from hyper-excitability of the stretch reflex, as         quent implantation of the pump.
one of the components of the upper motor neurone syn-                  ITB therapy is absolutely contraindicated in patients
drome.1 For some patients neurolysis or chemodenerva-               with active infection, allergy to baclofen, and in pregnan-
tion with botulinus toxin or phenol may be useful, partic-          cy (since baclofen may be teratogenic).5
ularly for focal spasticity. The intrathecal administration
of baclofen (ITB) offers a safe and effective alternative to
                                                                      Chart 1: Contraindications to ITB therapy                                   Sohail A Ansari qualified from
oral medications that may be ineffective in some patients                                                                                         Karachi and trained in London,
with severe diffuse spasticity due to a variety of causes             Relative contraindications                                                  Swansea and Lyon. He worked as a
including multiple sclerosis, cerebral palsy, traumatic and                                                                                       consultant neurosurgeon in Riyadh,
                                                                      • Poor trunk control with reduced spasticity                                Saudi Arabia. More recently he has
hypoxic brain injury, and spinal cord injury. It is also              • Pre-existing bladder problems                                             been working as a locum consultant
effective in the management of spasticity resulting from              • Anticoagulation therapy                                                   in London hospitals. He has a spe-
cerebral palsy in children.11 Several studies from North                                                                                          cial interest in neurostimulation,
America have also shown considerable economic benefits                                                                                            spasticity and chronic pain man-
                                                                      Absolute contraindications                                                  agement.
resulting from reduced in-patient costs and related fees.2,8,9        • Active infection
                                                                      • Allergy to oral baclofen
Intrathecal Baclofen (ITB)                                            • Pregnancy
ITB involves the continuous delivery of baclofen from an
implanted pump, situated subcuta-
neously in the anterior abdominal                                                         Benefits of ITB therapy
wall, connected to a catheter whose                                                       Objective improvements are seen in
distal end lies within the lower dor-                                                     the form of reduced muscle tone,
sal subarachnoid space (Figure 1).                                                        spasms and pain with increased
ITB therapy is a good alternative                                                         mobility, and improvement in                            Robert M Redfern undertook neu-
when physical methods and oral                                                            speech, sleep quality, bladder con-                     rosurgical training in Liverpool
medication (including muscle                                                              trol and self-image. Improvements                       and London, and since 1992 has
                                                                                                                                                  been a consultant neurosurgeon at
relaxants and oral anti-spasticity                                                        may also be seen in activities of                       Morriston Hospital, Swansea. His
drugs) fail to produce satisfactory                                       PUMP            daily living (ADLs), self-care, dress-                  sub-specialist interests are in pitu-
control of spasticity or are poorly        CATHETER                                       ing, sitting tolerance, movement,                       itary surgery, and intrathecal man-
tolerated. Baclofen is an agonist to
          4
                                                                                          transfers, orthotic wear and in                         agement of pain and spasticity.
a bicuculline-insensitive variety of                                                      overall comfort.          10


GABA receptors, known as GABA-                                                                                                                    Correspondence to:
B. A possible explanation for its                                                         Approach to ITB therapy                                 Mr R M Redfern,
effect on spinal cord functioning is                                                      a. Patient selection                                    Consultant Neurosurgeon,
                                                                                                                                                  Morriston Hospital,
triggering of a cascade of events Figure 1: Diagram of implanted                          b. Screening                                            Swansea,
that includes neuronal hyperpolari- programmable pump.                                    c. Pump implantation                                    West Glamorgan,
sation, with prevention of calcium                                                        d. Dose adjustment                                      SA6 6NL, UK.
influx and thus facilitation of potassium conductance and                                 e. Pump maintenance                                     Tel: 01792-703382
                                                                                                                                                  Email: robert.redfern@
inhibition of release of excitatory neurotransmitters. This                                                                                       swansea-tr.wales.nhs.uk
eventually leads to pre-synaptic inhibition with reduction    a. Patient selection
of both mono- and poly-synaptic reflexes and motor            The preferred approach involves a multidisciplinary
activity. As a consequence abnormal muscle tone and           assessment. Potential candidates for treatment will have
stretch reflex hyperexcitability are reduced, bringing        severe spasticity which has been inadequately controlled
about reduced spasticity.                                     by, or who have experienced significant side-effects with,
   Since baclofen is hydrophilic it crosses the blood-brain   standard drug treatments.
barrier poorly, leading to low CSF concentrations when
administered orally. Intrathecal delivery circumvents this       Chart 2: Indications for ITB therapy
property and intrathecal doses are typically 100 – 1000
times smaller than oral doses to achieve the same effect.        • Severe multiple joint spasticity, particularly in the lower limbs
The negative effects on arousal and cognition can thus be        • ADLs and mobility limited by spasticity
avoided. The effects of ITB are reversible and the treat-        • Spasticity that interferes with nursing care and hygiene
ment does not involve destruction of neural tissue.              • Spasticity refractory to other treatment modalities
                                                                      •   Severe side-effects with other treatment modalities
Inclusion criteria for ITB therapy                                    •   Complications of spasticity (contractures, pressure sores)
After a multidisciplinary assessment, treatment goals are             •   Painful spasms
agreed. Motivation and commitment of patients, families               •   Clonus interfering with transfer and mobilisation
and caregivers should be taken into consideration.                    •   Medical stability (infection-free, no unresolved medical issues)
Clinical, functional and psychosocial factors may also
have a bearing on the suitability of a patient for ITB ther-
apy.5 It may also be helpful to discuss alternative treatment       b. Screening trial – intrathecal testing
options in advance, in the event that ITB therapy proves            A variety of trial regimes may be utilised, the purpose
to be ineffective or poorly tolerated.                              being to ascertain if spasticity can be controlled with
                                                                    intrathecal baclofen, After establishing CSF access with a
Contraindications to ITB therapy                                    lumbar spinal drain we give an initial intrathecal test
Relative contraindications include unmasking of poor                dose of 5 micrograms (mcg) of baclofen to exclude any
trunk control due to latent weakness of muscle groups               allergic response. Thereafter incremental doses of

                                                                                                                                  ACNR • VOLUME 6 NUMBER 4 • SEPTEMBER/OCTOBER 2006   I 15
Neurosurgery

baclofen are given twice daily with a dosage                                                                patient should lie flat to minimise the risk of
                                                                            RADIO-TELEMETRY
interval of at least eight hours, and increasing                                                            spinal headache due to CSF leakage and also to
the dose by 25mcg each time. The response to                                                                prevent development of fluid accumulation
each dose and any adverse effects are noted.                                                                within the abdominal pocket.
With severe dystonia it can be helpful to
undertake a trial of continuous infusion of                                                                 d. Dose adjustment
baclofen.                                                                                                   If a manual pump has been placed (Cordis
   The onset of action of a single dose of                                                                  ‘Secor’ or Pudenz-Schulte system) patients can
baclofen is about two hours, with a peak effect                                                             decide for themselves when to pump, although
occurring usually in four to six hours. A posi-                                                             a daily routine is preferred. Once the pump
tive response is on average a one point drop in                                                             has been activated it cannot be reactivated
the Ashworth scores in the affected limbs, but                                                              again until after a delay in order to prevent
other factors to be noted include reduced pain                                                              accidental or deliberate overdosage.
or spasms, improvement in range of motion,                                                                     Constant-rate infusion systems have a pres-
positioning, and mobility.                                                                                  surised gas-filled chamber deep to the reser-
   Latent weakness may be uncovered after the                                                               voir; the gas is further compressed when the
baclofen and this may limit its usefulness in                                                               pump is refilled and, by virtue of the high
                                                         Figure 2: Diagram of telemetry wand.
some patients. It is limited to about six to eight                                                          resistance of the outlet tubing from the reser-
hours after a bolus administration. Excessive                                                               voir, the flow rate (and thus the delivery of
length of weakness may be seen in patients                                                                  drug to the CSF) remains constant until the
with multiple sclerosis.                                                                                    pump is refilled. With such pumps (Therex
                                                                                                            300 or Infusaid 400) dosage can only be
c. Surgical implantation                                                                                    adjusted by emptying the pump and refilling it
Prior to implantation of the ITB pump the                                                                   with a different concentration of baclofen.
patient should be medically stable, infection-                                                                 With programmable pumps (Medtronic
free, but may continue on oral spasmolytic                                                                  SynchroMed range) the rate can be adjusted
medication (which can be gradually with-                                                                    using an external programmer that interro-
drawn in the early postoperative period).                                                                   gates and re-programmes the chip in the
   The site of pump placement is evaluated                                                                  pump (Figure 2). The pump can be set to
and marked on the skin, taking into consider-                                                               deliver at rates by day and by night – or even
ation factors such as the patient’s belt line, the                                                          more frequent alterations. The SynchroMed
                                                         Figure 3: The Synchromed II infusion system.
wheelchair armrest position, and any orthosis.                                                              Infusion System (Figure 3) consists of a small
It may also be necessary to consider the posi-                                                              titanium disk about 7.5cm in diameter and
tion of any stoma site since many of these               to the subcutaneous tissues. A subcutaneous        2.5cm thick which contains a refillable reser-
patients may have a colostomy, urinary diver-            abdominal pocket is now fashioned, just large      voir and a computer chip that regulates the
sion or feeding gastrostomy. Ideally the posi-           enough to contain the pump, and passing dis-       battery-operated pump; and, in common with
tioning of the pump site should be agreed with           tally far enough that the pump does not lie        other systems, a fixable silicone catheter that
the patient, family and carer. Informed con-             beneath the incision, thereby minimising the       serves as a pathway from the pump to the
sent should include a discussion about expec-            risk of wound dehiscence. The pump is now          intrathecal space. Dosage should not be
tations of treatment with ITB, and the pro-              filled with baclofen and the proximal end of the   adjusted more frequently than every 24 hours
posed arrangements for aftercare and the need            catheter attached prior to placement of the        in order to allow for stabilisation of the
for periodic refilling of the pump; and the              pump within the pocket to which it is anchored     intrathecal baclofen concentration and incre-
need for the pump to be replaced after an                with retaining sutures. The procedure usually      mental increases, if indicated, of 10-20%
interval of approximately five to seven years,           takes about one hour. The pump can be pro-         should be made for patients with spasticity of
the average battery life.                                grammed so that the catheter is flushed and a      spinal cord origin, and of 5-10% for children
   The pump is implanted under general anaes-            therapeutic rate of baclofen delivery is com-      and for adults with spasticity of intracerebral
thesia. Incisions are made in the lower midline          menced at the end of the procedure.                origin. Typical maintenance doses in our series
lumbar region and in the right hypochondri-                  Since the effectiveness of baclofen given      of patients receiving ITB for spasticity from a
um, at the site selected preoperatively. A fine          intrathecally seems to be greater with continu-    wide range of causes is of the order of 100-200
bore lumbar catheter is passed via a Tuohy nee-          ous administration rather than with a single       mcg per 24 hours.
dle such that its tip lies in the lower thoracic         bolus dose, a simple guide to total daily
region and CSF flow is established. In passing           administration is to set the pump to deliver       e. Pump maintenance
the lumbar catheter care should be taken to              1.5 times the minimal effective bolus dose         Periodic refilling of the reservoir with baclofen
pass it slightly off the midline to minimise the         established during the ITB trial. The eventual     will need to be performed approximately every
risk of late damage to the catheter by the ‘scis-        rate of delivery will need to be established       6-12 weeks depending upon the rate of daily
soring’ action of the adjacent lumbar spinous            somewhat empirically over the next few days        infusion. Dose titration can be further fine-
processes. From the abdominal incision a sec-            by titrating the dose to the observed response.    tuned during this stage, the aim being to con-
ond catheter is tunnelled subcutaneously,                    Postoperatively a pressure dressing may be     trol (but not to abolish) spasticity to the point
attached to the lumbar catheter, and anchored            applied to the abdominal wound and the             that the limbs can be managed easily and the




Since its introduction in the 1980s long-term administration
of ITB has proved to be a safe, well-tolerated and
cost-effective treatment for severe spasticity in adults
and children
16 I ACNR • VOLUME 6 NUMBER 4 • SEPTEMBER/OCTOBER 2006
                                                                                                                                                  Neurosurgery

patient is enabled to perform functional tasks.                                                                den withdrawal may result in a rare but poten-
                                                          Chart 4: Side effects and overdose symptoms
Careful re-assessment should be undertaken at                                                                  tially life-threatening condition (see above).
                                                          of baclofen6
regular intervals.                                                                                             Baclofen overdosage can be dealt with by
   To refill the reservoir the pump is emptied            Common side effects                                  adjusting the rate of administration but with
and a new supply of baclofen (for intrathecal             • Drowsiness, tiredness                              major overdosage the patient may become
administration) is injected using a special refill        • Increased weakness                                 weak, apnoeic or unconscious. (Such a condi-
kit supplied by the manufacturers. This involves          • Dizziness, lightheadedness                         tion may arise if, for example, the patient is
the use of a non-coring 22-gauge, Huber-type              • Mild confusion                                     inadvertently placed in an MRI scanner, for
needle to reach the reservoir through its sili-           • Constipation                                       which reason extreme caution should be taken
cone septum. The pump is then repro-                      • Bladder disturbance                                before subjecting patients with implanted
grammed. The programmable pumps emit a                    • Sleep disturbance                                  infusion devices to such investigation.
low reservoir alarm sound if a preset level is            • Ataxia                                             Temporary explantation of the pump may
reached (usually 2ml of their 18ml capacity).                                                                  even need to be considered if a strong indica-
                                                          Symptoms of overdose
   The procedure is performed with sterile                                                                     tion for MRI scanning exists). Treatment of
                                                          • Drowsiness
precautions in a clean environment. We have                                                                    the condition requires intensive care unit
                                                          • Lightheadedness
found it beneficial to have each patient allocat-                                                              admission where endotracheal intubation and
ed to a dedicated nurse trained in spasticity             • Sudden onset of blurred vision of diplopia         assisted ventilation may be required. The
assessment and in pump maintenance. This                  • Vomiting                                           pump should be stopped (or removed) and
not only gives a useful point of contact for the          • Seizures                                           respiratory depression should be reversed with
patient and their carer, but also reduces the             • Fever                                              physostigmine 1-2mg intravenously.
infection risk that might arise with pump                 • Coma
refilling being performed by less experienced                                                                  Summary
staff undertaking the procedure on an occa-                                                                    Since its introduction in the 1980s long-term
sional ad hoc basis.                                    fairly simple to rectify. It is important to explain   administration of ITB has proved to be a safe,
                                                        to patients in advance of implantation that such       well-tolerated and cost-effective treatment for
Further rehabilitation after ITB pump                   complications may arise since once established         severe spasticity in adults and children. It is of
placement                                               ITB is generally well tolerated and can bring          benefit in patients with spasticity due to cere-
Since the problems caused by spasticity are             about considerable improvement in quality of           bral or spinal causes and the beneficial effects
numerous and multi-faceted a team approach              life. Examples of the range of complications are       tend to be maintained in the longer term. The
for continuing management is required.                  given in Chart 5.                                      reduction in spasticity leads to functional
Further treatment may involve stretching,                  One of the commoner complications is                improvement and pain relief and, in patients
strengthening, conditioning and motor                   catheter leakage, due to kinking or fracturing,        with severe disability, ease of nursing care.
retraining. Serial casting or tendon release            and this usually presents as an apparent loss of       Furthermore the reduction in severe diffuse
procedures can also be undertaken to achieve            efficacy of ITB with increasing spasticity or          spasticity in stroke patients is not accompa-
maximum elongation after spasticity has been            unpredictable variation in effectiveness of the        nied by adverse effects on arousal or on cogni-
successfully treated.                                   drug.                                                  tion.3 However there is a risk, particularly in
                                                           Occasionally the spinal catheter tip can            ambulatory patients, of unmasking underly-
                                                        cause irritation of a lumbar nerve root with           ing muscle weakness. Although complications
  Chart 3: Rehabilitation guidelines after ITB
                                                        resulting unilateral sciatica. Re-opening of the       are relatively common these tend to be
  pump placement
                                                        lumbar incision under general anaesthetic and          amenable to relatively simple measures.
  • Re-assess the patient as new                        withdrawal of the catheter by 1-2cm usually
  • Elongate shortened tissues through stretching       results in complete resolution of this problem.
    and serial casting or tendon release procedures        ITB has CNS depressant properties and sud-
                                                                                                               References
  • Initiate strengthening programme, knowing
                                                                                                               1. Ansari S, Al Moutaery K. Spasticity: Comprehensive
    spastic muscles are weak
                                                          Chart 5: Complications of ITB therapy                    management. 2002.
  • Attempt to re-establish motor control and                                                                  2 Becker WJ, Harris CJ, Long ML et al. Long term intrathe-
    coordination                                          Patient-related                                          cal baclofen therapy in patients with intractable spasticity.
  • Re-evaluate orthoses, adaptive equipment and          • Hypersensitivity to baclofen                           Can J Neuol Sci 1995;22:208-17.
    seating systems                                       Operator-related                                     3. Francisco GE. Intrathecal baclofen therapy for stroke-
  • Modify the home programme and family training                                                                  related spasticity. Top Stroke Rehabil 2001;8(1):36-46.
                                                          • Programming error
  • Employ other antispastic medicines to optimise                                                             4. Francisco GE. The role of baclofen therapy in upper motor
                                                          • Drug concentration error                               neuron syndrome. Eur Med Phys 2004;40:131-43.
    the functional outcome eg Botulinum toxin             Complications of test doses                          5. Gudesblatt M. Use of intrathecal baclofen therapy in
    injections to treat residual focal spasticity         • Nausea or vomiting                                     management of the brain injured patient. Coma Recovery
                                                          • Sedation                                               Ass 2002.
                                                          Procedure-related                                    6. Kalb RC. Multiple sclerosis: the questions you have – the
Adverse effects of baclofen                                                                                        answers you need. [3rd edition]. National Multiple
ITB has CNS depressant properties causing                 • CSF leak and spinal headache; CSF collection           Sclerosis Society. Intrathecal Baclofen Therapy (ITB).
sedation, somnolence, dizziness, drowsiness,              • Pump socket seroma                                 7. Mohammed I, Hussain A. Intrathecal withdrawal syn-
ataxia and possible cardiac and respiratory               • Infection                                              drome – a life threatening complication of Baclofen pump:
                                                          • General anaesthesia risks                              a case report. BMC Clin Pharmacol 2004;4:6.
depression.
                                                          Pump-related                                         8. Nance P, Schryvers O, Schmidt B et al. Intrathecal
  Rapid reduction of baclofen administration                                                                       baclofen therapy for adults with spinal spasticity: thera-
may result in ITB withdrawal syndrome, a rare             • Flipping of pump                                       peutic efficacy and effect on hospital admissions. Can J
and life-threatening condition consisting of              • Failed pump                                            Neurol Sci 1995;22:22-9.
pruritus, rash, anxiety, disorientation, fever            • Power failure                                      9. Ordia JI, Fischer E, AdamskiE et al. Chronic intrathecal
and cardiovascular instability.7                          Catheter-related                                         delivery of baclofen by a programmable pump for the
                                                                                                                   treatment of severe spasticity. J Neurosurg 1996;85:452-7.
                                                          • Kinking
                                                                                                               10. Stempien L, Tsai T. Intrathecal baclofen pump use for
Complications of ITB therapy                              • Fracture                                               spasticity: a clinical survey. Am J Phys Med Rehab
Complications of ITB treatment are common and             • Occlusion                                              2000;79(6):536-41.
in most cases mild and reversible but some, par-          • Dislodgement                                       11. Turner MS. Early use of intrathecal baclofen in brain
ticularly those related to the catheter, can be trou-     • Catheter tip fibroma                                   injury in paediatric patients. Acta Neurochir Suppl.
blesome to diagnose even though ultimately                                                                         2003;87:81-3.


                                                                                                                          ACNR • VOLUME 6 NUMBER 4 • SEPTEMBER/OCTOBER 2006   I 17

								
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