IMAGING DIAGNOSIS: TRAUMATIC DURAL TEAR DIAGNOSED USING

INTRATHECAL GADOPENTATE DIMEGLUMINE

ALBERTO MUNOZ, ISIDRO MATEO, VALENTINA LORENZO, JERoNIMO MARTINEZ

A dog with traumatic monoplegia had a spinal cord lesion, identified using conventional magnetic resonance

imaging. In addition, the intrathecal use of gadopentate dimeglumine allowed identification of two sites of cere-

brospinal fluid leakage from the vertebral canal, supporting a diagnosis of brachial plexus avulsion. Veterinary

Radiology & Ultrasound, Vol. 50, No. 5, 2009, pp 502–505.

Key words: intrathecal gadolinium, MRI, spinal CSF fistula.

History and Physical Findings

A2-YEAR-OLD, Jack Russell terrier had stupor and acute

motor dysfunction of all limbs after being hit by a

car. There were no radiographic abnormalities of the spine

or skull. There was paresis of the left thoracic limb

and both pelvic limbs, worse on the right, monoplegia of

the right thoracic limb, and right Horner’s syndrome. The

patient was treated symptomatically and 1 week later the

stupor had resolved, the paresis had improved but a right

monoplegia persisted. There were also postural reaction

deficits in the right thoracic limb and both pelvic limbs.

Spinal reflexes and superficial and deep pain perception

were absent in the right thoracic limb. Right brachial

plexus avulsion was considered.

Imaging

Magnetic resonance (MR) imaging was performed using

a superconducting 0.5T system.� T2-weighted fast spin

echo (4000/110/16; TR/TE/echo train) images of the cervi-

cal spine and cranial portion of the thoracic spine were

acquired in sagittal and transverse planes and T1-weighted

spin echo (SE) images (500/14; TR/TE, Gd-DTPA dose

was 0.1mmol/kg, intravenous [IV]) were also acquired in

the transverse plane after IV administration of Gd-DTPA.wAfter conventional imaging, an atlanto-occipital punc-

ture was performed and 1ml of cerebrospinal fluid (CSF)

was withdrawn. The CSF was mixed with 0.5ml Gd-

DTPA and re-injected intrathecally via the same puncture.

The patient was positioned upright for 5–6min followed by

acquisition of T1-weighted SE transverse images and fat-

saturated T1-weighted transverse images using the same

acquisition parameters as before. Intrathecal administra-

tion of Gd-DTPA was used as a diagnostic tool to identify

a potential meningocele or CSF leakage, abnormalities that

are easily missed in standard MR images.

A T2-hyperintense medullary lesion was seen at the level

of the first thoracic vertebra. Nerve rootlets could not be

identified (Fig. 1A). Focal spinal cord trauma was sus-

pected. There was also diffuse T2-hyperintensity involving

ventral paravertebral soft tissue (Fig. 1B). There was no

evidence of contrast enhancement in the spinal cord or

the ventral paravertebral soft tissue. After intrathecal ad-

ministration of Gd-DTPA, two contiguous hyperintense

extravasations were identified extending through the inter-

vertebral foramina at C7–T1 and T1–T2 on the right side.

These hyperintensities followed the correspondent nerve

root pathway into the right ventral paraspinal musculature

and pooled into the interfascial paravertebral spaces (Fig.

2). This finding was consistent with extravasation of intra-

thecal contrast medium due to a dural tear, and supported

the diagnosis of brachial plexus avulsion.

Twenty-four hours later, the dog had a depressed mental

status and central blindness. These signs were thought to be

due to intracranial hypotension associated with the contin-

uous CSF leak. The dog recovered to the preimaging neu-

rologic status in 36h. Fifteen days after imaging, the dog was

able to walk unassisted but right thoracic limb monoplegia

persisted and muscle atrophy had developed in the limb.

Discussion

Traumatic brachial plexus injury can be diagnosed clin-

ically and by electrophysiologic means. However, the ana-

tomic consequences of the injury can only be demonstrated

by imaging. Conventional myelography, computed tomo-

graphy (CT) myelography with intrathecal water-soluble

contrast medium and radionuclide cisternography have

Address correspondence and reprint requests to Isidro Mateo, at theabove address. E-mail: isidro_mateo@yahoo.esReceived February 19, 2009; accepted for publication April 28, 2009.doi: 10.1111/j.1740-8261.2009.01567.x

From the Facultad de Medicina, Departamento de Radiologıa y Me-dicina Fısica, Universidad Complutense de Madrid, Madrid, Spain(Munoz) and Resonancia Magnetica Veterinaria, Madrid, Spain (Mateo,Lorenzo, Martınez).

�Gyroscan T5-NT, Philips, Amsterdam, the Netherlands.wMagnograf, Schering, Madrid, Spain.

502

been used to diagnose brachial plexus avulsions in humans.1

CT myelography has been used to diagnose brachial plexus

avulsions in three dogs and one cat.2 Conventional MR

imaging is a standard procedure used in humans to detect

nerve root avulsions although it is less reliable than CT

myelography.3 Reasons for unreliable or inconsistent find-

ings in MR imaging are partial root avulsions, presence of

intradural fibrosis, traumatic meningoceles, and motion

Fig. 1. (A and B) Transverse T2-weighted image at the C7–T1 intervertebral disc space. There is a hyperintense intramedullary lesion (arrows in A) anddiffuse T2-hyperintensity involving ventral paravertebral soft tissue (arrows in B) (TR 4000ms, TE 110ms, slice thickness 4mm, FOV 14cm).

Fig. 2. (A and B) Consecutive transverse fat-saturated T1-weighted images at the level of C7–T1 (A) and T1–T2 (B), after intrathecal injection of Gd-DTPAThe hyperintensity tracking from the intervertebral foramen towards the ventral intermuscular area is consistent with a cerebrospinal fluid leak (TR 500ms, TE14ms, slice thickness 4mm, FOV 15cm).

503TRAMAUTIC DURALTEARVol. 50, No. 5

artifacts.3 Typical MR imaging findings in humans with

brachial plexus avulsions are: (1) intramedullary T2-hyper-

intensity suggesting edema or myelomalacia or T2-hypoin-

tensity suggesting hemorrhage in approximately 20% of

patients with preganglionic injuries, (2) contrast enhance-

ment of intradural nerve roots and root stumps that suggest

functional impairment of nerve root despite nerve root

continuity, and (3) contrast enhancement of paraspinal

muscles.1 At 0.5T, depiction of nerve rootlets is difficult.

Intrathecal administration of Gd-DTPA will increase the

detection of traumatic meningoceles or dural tears with

CSF leakage.4 Depiction of a dural tear can be useful in

patients with brachial plexus injury because it will lead to a

more precise localization of the lesion.

Gd-DTPA was the first contrast medium approved for

IV use in MR imaging studies and the benefits of intra-

thecal Gd-DTPA to study CSF pathway disorders, includ-

ing tolerance and dose limits, have been described.5–9

Intrathecal paramagnetic contrast media allow specific di-

agnosis of some lesions otherwise missed in conventional

MR imaging.

CSF leaks are the most common condition in which in-

trathecal use of Gd-DTPA is used in humans, particularly

in CSF rhinorrhea where it is necessary to localize the fis-

tula.10 Intrathecal Gd-DTPA has been used to detect CSF

spinal leakage, which is the most common cause of spon-

taneous intracranial hypotension in humans.11 Other indi-

cations for intrathecal Gd-DTPA use in humans are

evaluation of cystic masses, congenital obstructions and

communications of the subarachnoid space, cystic ar-

achnoiditis, and differentiation between an empty sella and

an intrasellar cyst.12,13

Reports of CSF leakage in animals are scant.14–19 Dural

rupture in animals is typically associated with trauma or

vigorous exercise.16,17 In most patients, extravasated con-

trast medium was present in the epidural space,14,17 but it

has also been noted in the ventral paravertebral muscles,17

extrapleural space,18 and into a ruptured intervertebral

disc.19 In all patients but one, definitive diagnosis was made

using conventional myelography. In the subarachnoid

–extrapleural fistula, CT–myelography was used.18

When intrathecal Gd-DTPA is used in doses sufficient to

increase signal from the CSF, it is unlikely that it promotes

acute changes in neural function or structure.4,7 In our

patient, a mixture of 0.5ml Gd-DTPA (500mmol/ml) with

1ml of CSF was administrated. The average weight of an

adult medium-sized dog brain is 72g. Therefore, we ad-

ministered a dose of 3.42mmol Gd-DTPA/g of brain tissue.

Gd-DTPA produces acute excitation, persistent ataxia and

widespread brain lesions in rats at dosages higher than

5mmol/g brain, but not at doses lower than 3.8mmol/g

brain.7 Higher doses, up to 140mmol/g brain, have been

used in dogs to locate the source of CSF rhinorrhea with-

out recognized side effects.5 Nevertheless, lower concen-

trations (0.17mmol/g brain) are sufficient for enhancement

of the subarachnoid space in humans.13

In our patient, a spinal cord lesion that related directly

to the clinical findings was identified in conventional MR

imaging. However, only intrathecal Gd-DTPA use allowed

the detection of the dural tear with CSF leakage.

Deterioration of the neurologic status in our patient af-

ter intrathecal Gd-DTPA injection could be attributed to

the neurotoxic effect of the Gd-DTPA or a decrease in

intracranial pressure due to CSF puncture and leakage.

The development of the new neurologic signs, 424h after

intrathecal Gd-DTPA injection, supports the intracranial

hypotension hypothesis.20 We have used similar a concen-

tration of Gd-DTPA intrathecally, both in humans12 and

dogs (unpublished data), with no neurological or systemic

side effects.

Intrathecal Gd-DTPA use is not currently approved by

the United States Food and Drug Administration and is

used off-label. Therefore, its clinical use should be consid-

ered carefully and always performed assessing risks and

benefits, having in mind that this procedure is potentially

the most accurate and less risky in the diagnosis of CSF

leaks. Owners should be informed and asked to sign spe-

cific informed consent, detailing risks and benefits.

ACKNOWLEDGEMENTS

The authors thank Juan San Nicolas for his professional technicalassistance at the MRI unit.

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