Neurology -- Correspondence for Transverse Myelitis Consortium Working Group*, 59 (4) 499-505

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Correspondence published:

Reply to Letter to the Editor: Douglas Kerr (30 October 2002)

Proposed diagnostic criteria and nosology of acute transverse myelitis: Gustavo C Roman (30 October 2002)

Reply to Letter to the Editor 30 October 2002

Douglas Kerr
Johns Hopkins Hospital Baltimore MD
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Re: Reply to Letter to the Editor

dkerr{at}jhmi.edu Douglas Kerr

We appreciate the interest in our article detailing the diagnosis and classification of acute transverse myelitis (ATM) [1] and your comments. Our primary goal was to delineate an approach to ATM, and therefore, we did not describe the diagnosis and evaluation of patients with non- inflammatory myelopathies. However, Dr. RomÜn raises an important point: that we may mistakenly diagnose a patient who has nucleus pulposus embolism (NPE) with ATM. We suggest that this is unlikely to occur for several reasons. You and others have advanced our understanding of NPE, [2-6, 7, 8] reporting that the majority of patients progress to nadir in less than four hours. Additionally, most patients with NPE have acellular, non-inflammatory CSF and no abnormal gadolinium enhancement on spinal MRI imaging. [2-6] Indeed, the pathology in both humans and animals with NPE [9-11] suggests ischemic infarction of the spinal cord rather than a primary inflammatory process. Therefore, most patients with NPE would be excluded by our criteria from a diagnosis of ATM.
We do not think that acute severe back pain is the exclusive domain of NPE, and rather that this symptom may occur in patients with a variety of spinal disorders, especially those with meningeal and radicular involvement. Therefore, to add acute back pain as an exclusion criterion for ATM would, in our opinion, be unfounded.
It is presently uncertain how common NPE is, though we agree that it is likely under diagnosed. A patient with acute, non-inflammatory myelopathy and disc space collapse at the site of deficit should be considered to have NPE, especially if there is a recent
history of trauma. Even so, NPE likely represents a rare cause of acute myelopathy, and it would be misleading to say that this entity is “often” or “frequently” misdiagnosed.
Finally, there is no reported successful treatment of NPE, and hyperbaric oxygen treatment should not be considered as “indicated” treatment until studies suggest that it is effective.
References:
1.Transverse Myelitis Consortium Working Group. Proposed diagnostic criteria and nosology of acute transverse myelitis. Neurology 2002;59:499- 505.
2.Toro G, RomÜn GC, Navarro-RomÜn L, Cantillo UJ, Serrano B, Vergara I. Natural history of spinal cord infarction caused by nucleus pulposus embolism. Spine 1994;19:360-366.
3.Bots GT, Wattendorff AR, Buruma OJ, Roos RA, Endtz LJ. Acute myelopathy caused by fibrocartilaginous emboli. Neurology 1981;31:1250- 1256.
4.Case records of the Massachusetts General Hospital. Case 5-1991. N Eng J Med 1991;324:322-332.
5.Davis GA, Klug GL. Acute-onset nontraumatic paraplegia in childhood: Fibrocartilaginous embolism or acute myelitis? Child’s Nerv Syst 2000;16:551-554.
6.Tosi L, Rigoli G, Beltramello A. Fibrocartilaginous embolism of the spinal cord: A clinical and pathogenic reconsideration. J Neurol Neurosurg Psychiatry 1996:60:55-60.
7. Schreck et al., Nucleus pulposus embolism. Spine, 1995; 22; 2463- 2466.
8. Yousef et al., Fibrocartilagenous embolism: an unusual cause of spinal cord infarction. Am J Forensic Med Pathol, 1998; 4; 395-399.
9. Stedman et al., Intravascular cartilaginous emboli in the spinal cord of turkeys. Avian Disease, 1998; 42; 423-428.
10. Cauzinille and Kornegay, Fibrocartilaginous embolism of the spinal cord in dogs: review of 36 histologically confirmed cases and retrospective study of 26 suspected cases. J. Vet Intern Med, 1996; 10; 241-245.
11. Junker et al., Fibrocartilaginous embolism of the spinal cord (FCE) in juvenile Irish Wolfhounds. Vet Q, 2000; 22; 154-156

Proposed diagnostic criteria and nosology of acute transverse myelitis 30 October 2002

Gustavo C Roman
The University of Texas Health Science Center at San Antonio
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Re: Proposed diagnostic criteria and nosology of acute transverse myelitis

neuro_journal{at}urmc.rochester.edu Gustavo C Roman

The Transverse Myelitis Consortium Working Group is to be congratulated for the proposed diagnostic criteria and nosology of acute transverse myelitis (ATM). [1] However, in the differential diagnosis only scarce attention was given to fibrocartilaginous embolization from nucleus pulposus embolism (NPE), a condition that is often undiagnosed and frequently confused—clinically and pathologically—with ATM. [2] For instance. Bots et al. [3] reexamined a teaching specimen of so-called ATM and found an acute transverse myelopathy due to NPE.
Although the exclusion criterion of <4 hours from onset to nadir would effectively exclude most vascular cases, in our review of the natural history of NPE [2] we found that at least 42% of the cases had progressed for periods of >4 hours, furthermore, a prodromal history of intermittent back pain is not uncommon, lasting for periods of weeks to up to 4 months. [4] The bimodal age distribution of ATM is also found in NPE, with peaks at 22 and 60 years, [2] with the earliest reported case in a 6- year-old girl. [5]
The distinguishing feature of NPE is the sudden onset of severe pain, localized in the neck or interscapular region in cases with cervical cord ischemia, or with back pain when the lumbosacral spinal cord is involved. [2, 6] It is conceivable that the traditional notion that the presence of pain in patients with ATM is associated with poor prognosis [1] could have resulted from inaccurate inclusion of NPE cases. It would be advisable, therefore, to add as an exclusion criterion the onset of weakness accompanied by pain.
In NPE there is usually rapid onset of weakness, from minutes to up to 48 hours, [2, 6] with no substantial recovery. The cervical/cervico- medullary cord is involved in 70% of cases, the lumbosacral and conus medullaris segments in 22% and the thoracic cord in 8% [2, 6] but involvement of several adjacent segments is common.
According to Tosi et al., [6] the diagnosis of NPE can be made with accuracy by MRI showing cord swelling, with increased signal on T2- weighted images, associated with a collapsed disc space at the appropriate level. A correct diagnosis of NPE may have more than academic implications considering the successful treatment of spinal cord embolism with hyperbaric oxygen (HBO) therapy in decompression sickness. [7, 8] Given the dismal prognosis of NPE, immediate treatment with HBO is probably indicated.
References:
1.Transverse Myelitis Consortium Working Group. Proposed diagnostic criteria and nosology of acute transverse myelitis. Neurology 2002;59:499- 505.
2.Toro G, RomÜn GC, Navarro-RomÜn L, Cantillo UJ, Serrano B, Vergara I. Natural history of spinal cord infarction caused by nucleus pulposus embolism. Spine 1994;19:360-366.
3.Bots GT, Wattendorff AR, Buruma OJ, Roos RA, Endtz LJ. Acute myelopathy caused by fibrocartilaginous emboli. Neurology 1981;31:1250- 1256.
4.Case records of the Massachusetts General Hospital. Case 5-1991. N Eng J Med 1991;324:322-332.
5.Davis GA, Klug GL. Acute-onset nontraumatic paraplegia in childhood: Fibrocartilaginous embolism or acute myelitis? Child’s Nerv Syst 2000;16:551-554.
6.Tosi L, Rigoli G, Beltramello A. Fibrocartilaginous embolism of the spinal cord: A clinical and pathogenic reconsideration. J Neurol Neurosurg Psychiatry 1996:60:55-60.
7.Frankel HL. Paraplegia due to decompression sickness. Paraplegia 1997;14:306-311.
8.Ball R. Effect of severity, time to recompression with oxygen, and re-treatment on outcome in forty-nine cases of spinal cord decompression sickness. Undeersea Hyperb Med 1993;20:133-145.