Spasticity is one of the commonest sequelae of many neurological disorders like stroke, cerebral palsy, multiple sclerosis, trauma etc. At present only spasticity surgery in form of oral medications and Botulinum Toxin injections are available at most of the centers including our hospital. This is complemented by orthopedic interventions, intensive physiotherapy and rehabilitation. However, large numbers of patients have significantly residual spasticity for which there is no remedy.
Neurosurgical treatment for spasticity aims at providing relief to these patients. Surgical procedures like Neurotomies, Rhiozotomies, Intrathecal Baclofen combined with Orthopaedic interventions can be undertaken for the treatment of spasticity. Jaslok Hospital is the only center in India that deals with comprehensive surgical management of spasticity.
Neurotomy : It involves resecting part of the motor nerve responsible for spasticity, for e.g. median nerve, tibial nerve etc. It is useful in improving management of hemiplegic patients. The surgery is done with the aid of intraoperative nerve stimulator to identify and selectively disconnect the involved motor nerves.
Dorsal Root entry zone lesion : DREZotomy is indicated in patients with paraplegia and severe pain. In this surgery, lesion is made at the level of the dorsal horn where the sensory nerve roots enter. This interrupts the spinal reflex arc and hence relieves the spasticity. Following this surgery any scope of motor function returning is lost. Therefore this surgery is offered to those patients who have no chance of improving their motor function. The biggest advantage of this procedure is that it is only performed one time and the relief from spasticity is life-long. The surgery not only relieves the spasticity but also alleviates pain.
Selective Functional Dorsal Rhizotomy : In patients suffering from spasticity with preserved power, this surgery is indicated. It is most useful in cerebral palsy patients as it can selectively resect dorsal roots contributing to spasticity without affecting the motor power, thus improving their mobility.
Intrathecal Baclofen Pump : Intrathecal drug delivery is a viable treatment strategy for spasticity, neuropathic pain and nociceptive pain in the cancer population.
Intrathecal pump is a device used for chemical neuromodulation of central nervous system to significantly reduce spasticity and pain. It involves implantation of hardware to deliver the drug. In simple terms it is a completely internalized system comprising of an intrathecal catheter connected to a drug reservoir sited in superficial subcutaneous pocket. Administration of a drug into the subarachnoid space directly acts on the target receptors present on the dorsal horn cells responsible for pain transmission. The intrathecal administration permits the drug to bypass enteric absorption and/or blood brain barrier hence the dose required is a fraction of systemic dose with improved efficacy and minimized side-effects. For example, dose of baclofen from oral to intrathecal route decreases from approximately 300mg to 1mg. The continuous drug delivery ensures a steady drug level in blood, improving quality of analgesia. This in short is a modality which provides more effective pain relief with better safety profile.
Proper patient selection, meticulous implantation technique, maintenance and continued vigilance are of paramount importance to reduce predictable iatrogenic complications and ensure success .The decision to implant requires careful evaluation of multifaceted therapeutic measures to ensure optimal treatment outcomes. When considering a pump, clinicians must consider comorbidities related to disease and psychosocial factors such as death and dying issues, and life expectancy. Thorough explanation of what the therapy entails and need for continuous commitment for therapy titration on part of the patient and caretaker should be emphasised before proceeding. There are a number of drugs used with the system but three drugs which are at present FDA approved are Morphine, Baclofen and Ziconotide.
Intrathecal drug pump is a very sophisticated and programmable system. It involves two stages.First is a trial which is important to determine whether this particular system will suit that individual or not!! It is like test driving a car before buying. Trial is performed to assess patient’s response to spasticity and improvement in side effects. We perform trial using intraduralcatherter (not bolus), which is implanted in strict aseptic conditions at the desired target site. The patient is assessed for the improvement in spasticity after 2,4 and 6 hours. We usually observe the patient in ICU during this time for increased patient safety. If the trial is successful we proceed with the implantation. After implantation the system is programmed to offer long lasting benefit in terms of satisfactory control of pain.
The implantation is performed in OT using fluoroscopic guidance and all surgical asepsis. The two piece silicone catheter is introduced through a special introducer needle and guided into subarachnoid space upto the desired level depending on pain geography and property of the drug used. It is secured to thoracolumbar fascia with special anchor, tunnelled in subcutaneous plane and connected to the Synchromed pump by suture less connector on the proximal piece of the catheter. The pump is emptied of its manufacturing fluid and filled with the desired drug before implanting in the subcutaneous pocket. Both the incisions are surgically sutured neatly after adequate haemostasis.
Intrathecal pump is available in two main types, fixed rate [Isomed] and programmable [Synchromed] pump. Synchromed has two varieties, an older Synchromed El and newer Synchromed II system. Synchromed II has been an improved version and has been more popular due to features such as lighter and flatter implant, increased drug stability to 6 months, improved low reservoir flow accuracy. It comes in two different sizes 20ml and 40ml reservoir capacity. Improved software of Synchromed II stores all patient demographics and notes up to 1000 characters. It also stores catheter information and system log with last 30 events and patient activation log of last 80 events. This information is most useful when technical support is called for help. The information is presented in scrollable window to accommodate more information with multiple drugs. New software allows drug data up to 5 drugs with first drug as a primary drug.A personal therapy manager (PTM) is a compact device to enable patient to take extra boluses if required for the incidental or breakthrough pain. This gives a better degree of patient satisfaction.
- Tumor encroachment of the thecal sac
- Intracranial process that may lead to cerebellar herniation in the setting of cerebral spinal fluid leak
- Implant not feasible <2.5 cm from skin
- Coagulopathy, emaciation
- Morbid psychiatric conditions
- Local or Systemic infection
Disadvantages and Complications
The main drawback of using this system being used more widely especially in our country is the cost. There should be reasonable life expectancy [at least three months] before consideration of implanting this device. Assessments of cost-effectiveness suggest that cost savings are achieved after 2 years in comparison to systemic pharmacologic therapy for chronic, non-cancer pain.
Complications related to intrathecal therapy can be technical, biological, or medication related. While the vast majority of complications are minor, some serious complications can occur include Granuloma formation that may be related to the amount and concentration of opiates, mostly with high concentrations of Morphine and Hydromorphone. Surgical intervention required is rare as most cases improve with weaning off the intrathecal opiate, replacing it with preservative-free saline which has been shown to reverse the course leading to resolution of the Granuloma. Granuloma may occur in as many as 3% of implanted patients and most are asymptomatic. Routine MRIs to rule out intrathecal Granuloma was not recommended by the authors of this prospective study given the relatively low incidence . The earliest sign of Granuloma may be increased pain despite increasing opiate infusion; hence, clinical vigilance is of prime importance. Other complications of IDDS include catheter kinking, catheter fracture/ leakage, catheter migration, CSF leak, Seroma, Hygroma, Infection, Pump erosion through the skin, and medication side effects pruritus, nausea, vomiting, respiratory depression, and cognitive side effects may occur. It is important to realise that clinician skills and expertise is vital as programming errors can be lethal.
Maintenance and Follow up
A follow up at regular intervals [average every three months] is essential for refill of the drug in the pump reservoir and titration of the dose or drug to achieve the best possible analgesia. The battery of the pump requires surgical replacement about every 5-7 years depending on the flow rate used.
Adductor spasticity before surgery
Impaired range of movement after surgery
Severe spasticity and dystonia before Intrathecal Baclofen Trial