Ultrasound-guided Intrathecal Baclofen Trial: A Retrospective Case Series Examining a Novel Approach

Abstract

Spastic hypertonia is a common manifestation of the upper motor neuron syndrome that presents with increased muscle tone, hyperactive stretch reflexes, and clonus. The etiology is thought to be secondary to loss of inhibitory influences exerted by the cortex on the postural centers of the vestibular nuclei and reticular formation [1]. Untreated spastic hypertonia can lead to abnormal postures, painful spasms, and contractures, thereby limiting personal care and mobility. Traditional treatments include oral spasmolytics. However, these medications can produce intolerable adverse effects. The technological development of intrathecal baclofen (ITB) delivery has fostered the ability to deliver baclofen directly into the intrathecal space, which limits the systemic adverse effect profile. Before a permanent ITB system can be implanted, a patient must be screened for candidacy through trial. The trial protocol entails entering the intrathecal space by using a spinal needle and delivering a bolus of baclofen. Placement of the needle into the intrathecal space can prove challenging in patients with severe spasticity and associated postural and structural deformities, especially when a traditional blind needle placement technique is used. Furthermore, this technique relies heavily on cerebrospinal fluid (CSF) return and anatomic landmarks. Results of studies have shown that the absence of CSF flow after intrathecal placement occurs in 16%-25% of cases [2-4]. Furthermore, anatomic landmarks can be very difficult to localize. In a study by Broadbent et al [5] in 2000, the lumbar vertebral interspace was incorrectly identified by alpation 70% of the time. Yet another study by Furness et al [6], suggested that palpation isidentified the actual space in 58% of cases. One cannot predict technical difficulties or he accuracy of needle placement before skin puncture with any of the landmark-based echniques, which may lead to multiple attempts at epidural or intrathecal needle placeent, pain and discomfort to the patient, a failed ITB trial, complications, frustration for the perator, and poor patient satisfaction. Therefore, any alternative technique that can ircumvent some of these shortcomings and facilitate localization of the intrathecal space is esirable [7]. An alternative to the blind technique is use of fluoroscopy. One advantage of fluoroscopy ncludes the ability to confirm intrathecal placement with contrast myelography, whereas ltrasonography relies on needle visualization. However, fluoroscopy is expensive, exposes he patient to radiation, and often requires transportation of the patient to a procedure suite, ollowed by positioning onto a narrow procedure table, and can be difficult for patients with evere spasticity. In contrast, ultrasound has a lower cost, no radiation exposure, and can be erformed at the bedside or virtually anywhere, thereby improving patient comfort. We ropose that use of ultrasound for intrathecal baclofen trials may be a promising alternative o a blind or fluoroscopically guided technique. We present a series of 9 patients who nderwent ITB trials with ultrasound guidance, which illustrate advantages of this real-time edside imaging.