INDICATIONS FOR INTRATHECAL DRUG DELIVERY

Many patients with chronic pain will respond to a combination of physical therapy, oral medication and other conservative therapies. However, when non-interventional therapies lack effectiveness, oral analgesics cause intolerable side effects and further corrective surgeries fail to give adequate pain relief, intrathecal drug delivery (IDD) is an effective alternative.
General selection criteria for intrathecal drug delivery
As with neurostimulation, for IDD to be considered as a treatment option, patients should meet the following general selection criteria:
● There is an objective basis for the patient’s pain complaint
● The patient is psychologically competent and has no psychological contraindications
● Further corrective surgeries are likely to produce complications or poor outcomes
● More-conservative therapies have failed to relieve pain or have caused intolerable adverse events
● No contraindications to surgery exist (e.g. sepsis, coagulopathy)
● No untreated chemical dependency exists
● Neurostimulation and IDD are not contraindicated
IDD has proven efficacy in patients with intractable nociceptive pain where other therapies have failed, for example when oral analgesics have not been effective or cause intolerable side-effects. IDD has been used to successfully treat FBSS patients where pain is predominantly in the lower back, in multiple sites, or of a dominant nociceptive nature. IDD has also been used in cases where neurostimulation or a neurostimulation trial was unsuccessful and in difficult cancer pain and visceral pain cases.

Patient selection for intrathecal drug delivery
As with neurostimulation, before a patient becomes a candidate for IDD, the patient should undergo a thorough evaluation, which should include both physical and psychological elements. In addition, all patients should undergo a trial procedure.

Physical evaluation
A comprehensive history and physical examination of the patient should be completed to ensure that there is an objective basis for the pain. A complete pain history includes a general medical history with emphasis on the chronology and symptomatology of the pain. These data should include information about the onset, quality, intensity, distribution, duration, course and affective components of the pain, and details about exacerbating and relieving factors.
The physical examination should also include an appropriate neurological and musculoskeletal evaluation. The effects of pain, as well as the causes of pain, should be evaluated and recorded. In addition, the physician should determine the pain type, pain pattern, and sources of pain. Determination of such pain characteristics allows the physician to select the appropriate therapy.

Psychological evaluation
Most physicians agree that before considering a neuromodulation procedure, the patient should be assessed by a psychiatrist or a psychologist to rule out any psychological issues that may effect the therapeutic outcome.
This psychological evaluation should take place in the early phase of the patient selection procedure. A carefully performed psychological evaluation will have several benefits including, identifying those patients most likely to benefit from neuromodulation procedures and better preparing the patient for the neuromodulation procedure. It can also aid in preventing unsuitable candidates from undergoing an invasive and costly procedure and in redirecting rejected candidates to more appropriate treatment programs.
Intrathecal drug delivery trial procedure
The IDD trial period consists of an initial titration period, followed by an evaluation period in the patient’s home environment. Dose titration must be carried out in the hospital. For this, small intrathecal doses of medication are administered in a patient-controlled manner by the use of a patient-controlled analgesia pump. The patient can increase the dose until an acceptable level of pain relief is achieved. The aim of the titration period is to find an optimal balance between pain relief and prevention of the occurrence of side effects. Once an optimal dose is established, the patient is further tested on an outpatient basis. This permits the assessment of the efficacy of IDD in the patient’s home, and provides important information on improvements in quality of life and daily functioning. Ideally, the trial period should last between 3 to 4 weeks.

Indications for Intrathecal drug delivery
IDD is perceived to be most effective for nociceptive pain. In general, IDD is indicated for:
● Chronic, intractable pain of malignant or non-malignant origin
● Nociceptive or mixed pain
● Stable or changing pain patterns
In addition, IDD may be indicated for patients with non-malignant, intractable pain that is unresponsive to other treatments, patients who have undergone an unsuccessful neurostimulation trial, or for patients who experience intolerable adverse events from systemic opioid treatment.