++
Intrathecal drug delivery system (IDDS) trials offer the clinician an ability to utilize neuraxial medications in the patient and assess whether or not the patient has a positive response to the medications.
By delivering substances in this format, prior to committing the individual patient to surgical implantation of the device, the physician can be cost-effective, selective, and most importantly improve patient efficacy and safety.
There are 2 major categories of patients who would be considered for intrathecal pump infusion system trialing in the field of interventional pain management.
The first group suffers from neuropathic, nociceptive, or mixed pain syndromes which may be related to cancer pain or noncancer pain syndromes. Trialing often involves a primary opioid, ziconotide, or a combination of medications to treat different types of pain.
The second group suffers from poorly controlled spasticity, and involves the injection of baclofen.
The mechanics of needle and catheter placement may be similar between these groups; however, the assessment of the individual patient, with respect to outcome, differs significantly.
Trialing in the neuroaxis also varies based on the targeted area of drug delivery.
Options include single shot injections or catheter placement with intermittent bolusing or continuous infusion, and the anatomical location may be the epidural space or the cerebral spinal fluid.
++
Intrathecal pump infusion system trials are generally performed with placement of the needle below the conus, and the catheter in the area of the pain generator. The needle placement, generally, is performed between L1 and S1 in the interlaminar space. The specific anatomic points of consideration are as follows:
++
Visualization of the thoracolumbar junction at the lowest rib level
Visualization of the pedicles and spinous processes
Identification of the interlaminar spaces
Need drawing here of this anatomy
++
Other relative anatomy that should be considered includes:
++
The body habitus of the patient
The relative amount of lumbar lordosis present in the patient’s position on the table
The orientation of rotation of the spine in a patient with scoliosis
The integrity of the skin
The paraspinal musculature
The spinal ligamentous structures
The ligamentum flavum and the dura mater
+++
BASIC CONCERNS AND CONSIDERATIONS
++
There are some general concerns and considerations that would be applicable to all forms of IDDS trialing, whether the trial is performed as a single-shot, continuous epidural infusion or continuous intrathecal infusion.
++
The choice of interlaminar space:
++
The location should be based not only on adequate visualization of the interlaminar space, along with adequate space visualized to accommodate needle placement, but should also be based on entering the spine at a level with good skin integrity.
This includes an area absent of any evidence of skin breakdown or infection, and at a level where previous spine surgery has not been performed.
Areas of previous surgery may have atypical ...