Subdural injection of contrast medium as a complication of myelography

Usefulness of spinal unenhanced computed tomography and CT-myelography in the age of multidetector CT technology and magnetic resonance imaging - Preliminary considerations

Over the last decade, magnetic resonance imaging (MRI) and multidetector computed tomography (MDCT) have revolutionized diagnostic potential in small animal practice, providing adequate assessment of spinal diseases at levels comparable to that achieved in human radiology. T2-weighted MRI images are extremely sensitive to intramedullary parenchymal disorders, while balanced steady-state free precession sequences provide high-quality myelographic images of the spine without the need of intrathecal contrast medium administration. Multidetector computed tomography, with its near-isotropic spatial resolution and multiplanar reformatting of the acquired datasets, provides sufficient stratigraphic details of the spinal cord and the epidural space, facilitating the detection of compressive pathologies without the need of subarachnoid opacification. Nowadays, MDCT and low-field (LF) MRI have become fairly standard and available in academic institutions and private veterinary facilities, appearing to be valuable, complementary, and non-invasive diagnostic tools for imaging the spine. In this scenario, this clinical communication provides a series of preliminary observations that may help to reconsider the usefulness of CT-myelography in the light of its invasiveness and actual diagnostic advantages compared to MRI and unenhanced MDCT for the assessment of compressive and non-compressive spinal diseases in small animals.

Inadvertent Subdural Injection during Cervical Transforaminal Epidural Steroid Injection

Serious complications following cervical epidural steroid injection are rare. Subdural injection of local anesthetic and steroid represents a rare but potentially life threatening complication. A patient presented with left sided cervical pain radiating into the left upper extremity with motor deficit. MRI showed absent lordosis with a broad left paramedian disc-osteophyte complex impinging the spinal cord at C5-6. During C5-6 transforaminal epidural steroid injection contrast in AP fluoroscopic view demonstrated a subdural contrast pattern. The needle was withdrawn slightly and repositioned. Normal lateral epidural and nerve root contrast pattern was subsequently obtained and injection followed with immediate improvement in radicular symptoms. There were no postoperative complications on subsequent clinic follow-up. The subdural space is a potential space between the arachnoid and dura mater. As the subdural space is larger in the cervical region, there may be an elevated potential for inadvertent subdural injection. Needle placement in the cervical subdural space during transforaminal injection is uncommon. Failure to identify aberrant needle entry within the cervical subdural space may result in life threatening complications. We recommend initial injection of a limited volume of contrast agent to detect inadvertent subdural space placement.

Permanent monoparesis in a dog after intramedullary injection of iohexol into the lumbar spinal cord

Abstract

CASE HISTORY

An 8-year-old, spayed, Doberman Pinscher bitch presented for assessment of acute hindlimb paresis.

CLINICAL FINDINGS

During a lumbar myelographic contrast study a small volume of iohexol contrast agent was inadvertently injected into the cord parenchyma. After surgical hemilaminectomy for an intervertebral disc extrusion at L1-2 the dog recovered use of one hindlimb, but had ongoing extensor weakness of the left hindlimb. Left femoral nerve function had not returned after 14 months.

DIAGNOSIS

EMG findings 14 months after the incident indicated persistent femoral neuropathy consistent with the intramedullary contrast injection at L3-4.

CLINICAL RELEVANCE

Inadvertent deposition of iohexol into spinal cord parenchyma may be rare, but if it occurs it can have long-lasting consequences.

Contrast-enhanced CT for localizing compressive thoracolumbar intervertebral disc extrusion

Thoracolumbar intervertebral disc extrusion is a common disease in dogs. Surgical decompression of the spinal cord is the preferred treatment. Localization of the compressive material is critical for surgical planning. Myelography has been used for localizing extruded disc material, but this procedure carries risk of complications. Computed tomography (CT) is becoming more available for use in veterinary medicine and CT myelography is used for localization of extruded disc material. This report compares CT with intravenous contrast medium and CT myelography for identifying extruded intervertebral discs. CT with intravenous contrast medium is as effective as CT myelography for determining level and laterality of compressive disc extrusions.

Ultrasound-guided atlanto-occipital puncture for myelography in the horse

Complications of cervical myelography arising from the puncture of the subarachnoid space to collect the cerebrospinal fluid and to inject the contrast medium have been described in humans and animals. In this study, 2 ultrasound-guided procedures were developed for puncture of the atlanto-occipital subarachnoid space, collection of cerebrospinal fluid, and injection of contrast medium. Myelography was performed on 6 ataxic horses using these procedures. The first attempt to puncture the subarachnoid space was successful in 5 horses and in one horse, a second attempt was necessary. Collection of cerebrospinal fluid and injection of contrast medium were achieved without difficulty. Ultrasound-guided myelography allowed reduction of potential complications associated with blind percutaneous puncture of the subarachnoid space. Methods described in this study should be tried-at least initially in an experimental setting--to collect cerebrospinal fluid from the atlanto-occipital site in standing horses where it may represent an alternative method when lumbosacral cerebrospinal fluid collection has been unsuccessful or contaminated with blood.

Intervertebral disk disease

Neurologic dysfunction is the most common clinical manifestation of intervertebral disk disease. This article is a comprehensive review of intervertebral disk disease emphasizing clinical features, diagnosis and treatment of cervical and thoracolumbar disk disease. Clinical signs are determined by neuroanatomic localization and severity of spinal cord injury. Myelography is most commonly used for determining the location and extent of the disk protrusion/extrusion; however, computed tomography and magnetic resonance imaging are also common adjunctive and primary diagnostic techniques. Summaries from recent studies will give the clinician an improved understanding on how to confront controversial issues regarding prophylactic and therapeutic management and prognosis.