Published ahead of print on May 19, 2011
doi: 10.3174/ajnr.A2620

American Journal of Neuroradiology 32:E140, August 2011
© 2011 American Society of Neuroradiology

H.-f. Li^a and X.-j. Ji^b
aDepartment of Neurology
^bDepartment of Emergency Neurology 
Affiliated Hospital of Medical College 
Qingdao University, Qingdao 
Shandong, China

Although we appreciate the excellent images of enhanced cranial nerves in pediatric patients with Guillain-Barré syndrome (GBS) and their contribution to the understanding of GBS as a continuum rather than distinct entities, we do not agree with Zuccoli et al¹ that brain MR imaging should be considered inthe routine evaluation in pediatric patients with GBS.

First, we would like to know why the authors performed enhanced MR imaging in the clinically diagnosed and laboratory-supported patients with GBS. GBS is a well-known inflammatory disease of peripheral nerves, including the spinal nerves and cranial nerves. Albuminocytologic dissociation is the hallmark of GBS. Moreover, electrophysiologic examinations may reveal demyelinatingand/or axonal involvement. In the initial phase of GBS, breakdown of the blood-nerve barrier is the characteristic pathologic change, which may lead to enhancement of nerve roots. The study confirmed this. The diagnosis of GBS is based on clinical evaluation and electrophysiologic and CSF profiles.

Is there additional diagnostic value for GBS with an enhanced scan? In their series, 70.6% of the patients were found to have elevated CSF protein levels and 85.7% had positive electrophysiologic findings for GBS, which supported definite GBS.¹ The authors did not provide MR imaging data of patients with negative CSF or electrophysiology findings. Asymptomatic enhancement of nerve roots was found in this study, and the enhancement had no clinicalassociation.¹ If no other features support the diagnosis of GBS, perhaps the asymptomatic enhancement may give a clue to the inflammatory process of GBS. Moreover, the authors did not provide the relationship between enhancement and the clinical and electrophysiologic features. Therefore, we cannot know if enhancement may help to determine the subtypes of GBS (acute inflammatory demyelinating polyneuropathy, acute motor axonal neuropathy, or acute motor-sensory axonal neuropathy).

Second, we wonder whether the enhancement may have prognostic value. As the authors noted, though prominent nerve root enhancement accompanied an increased severity of leg weakness, the correlation between intracranial findings and clinical outcomes was poorly established. However, they did not provide the details of the outcome of the patients with enhanced nerve roots. The prognostic value will be determined by adjusting confounding factors, such as baseline severity, electrophysiologic classification (demyelinating or axonal), baseline CSF protein levels, immune-modulating therapies, and the time between scanning and the initial symptoms.

Third, is the enhancement significant in differentiating GBS from chronic inflammatory demyelinating neuropathy (CIDP) presenting as GBS? A small portion of patients with CIDP may present with relatively rapid progression to the nadir within 4 weeks after the onset, but they will relapse or progress in the long run.² Researchers have found several clues to differentiate it from GBS.³ Because enhancement and thickening of nerve roots is also seen in CIDP,⁴ the enhanced scan may help the differentiation. The grade of enhancement (absent, present, or strongly present) used in the Zuccoli study along with the morphology (thickening or not) may give a clue. Again, the time of scanning is important. We hypothesize that if there is a difference between GBS and CIDP presenting as GBS, the differential value will be maximal when scanning is performed in the “recovery” phase (eg, 6–8 weeks after the onset), when acute inflammation subsides in GBS while chronic inflammation persists in CIDP.

In conclusion, enhanced MR imaging need not be considered in the routine evaluation in GBS until its diagnostic, prognostic, and differential value is confirmed by prospective studies.

References

1. Zuccoli G, Panigrahy A, Bailey A, et al. Redefining the Guillain-Barré spectrum in children: neuroimaging findings of cranial nerve involvement. AJNR Am J Neuroradiol 2011;32:639–42[Abstract/Free Full Text]
2. Odaka M, Yuki N, Hirata K. Patients with chronic inflammatory demyelinating polyneuropathy initially diagnosed as Guillain-Barré syndrome. J Neurol 2003;250:913–16[CrossRef][Medline]
3. Dionne A, Nicolle MW, Hahn AF. Clinical and electrophysiological parameters distinguishing acute-onset chronic inflammatory demyelinating polyneuropathy from acute inflammatory demyelinating polyneuropathy. Muscle Nerve 2010;41:202–07[Medline]
4. Duggins AJ, McLeod JG, Pollard JD, et al. Spinal root and plexus hypertrophy in chronic inflammatory demyelinating polyneuropathy. Brain 1999;122:1383–90[Abstract/Free Full Text]

Reply

Published ahead of print on May 19, 2011
doi: 10.3174/ajnr.A2642

American Journal of Neuroradiology 32:E141, August 2011
© 2011 American Society of Neuroradiology

G. Zuccoli^a, A. Panigrahy^a, A. Bailey^a and C. Fitz^a
aChildren’s Hospital of Pittsburgh 
University of Pittsburgh Medical Center 
Pittsburgh, Pennsylvania

The authors of the letter had 3 main concerns regarding our article.¹ They first questioned our use of brain MR imaging and gadolinium contrast. When neurologic symptoms are present, our standard protocol includes administration of contrast material. All of the patients in our study had neurologic symptoms suggesting intracranial pathology; thus, they received brain imaging. The authors of the letter do not include imaging in their diagnostic criteria and believe that the disease is diagnosed by clinicalsymptoms, electrophysiology, and CSF abnormalities. Why then do they not criticize our use of spine imaging? Other authors disagree with them because in children, nonimaging findings may be confusing due to the nonspecific clinical presentation, thus resulting in delayed diagnosis and even death.²CSF and electromyography findings lag behind the clinical symptoms, thus supporting the usefulness of noninvasive techniques like MR imaging in children with suspected Guillain-Barré syndrome (GBS).^3–5 Furthermore, gadolinium-enhanced spine MR imaging is comparable with the criterion standard nerve conduction studies and may play a crucial role in the diagnosis of GBS, especially when specialist neurophysiology expertise is unavailable.⁶

The second question raised by the authors of the letter was whether the enhancement indicated prognosis. Because our article is retrospective in nature, it was not meant to indicate prognosis. The authors of the letter answered their own question by indicating that there are multiple factors involved in the prognosis.

The third question raised was the effectiveness of enhancement in separating chronic inflammatory demyelinating neuropathy from GBS. The authors themselves have indicated that enhancement is seen in both diseases. They believe that timing of the scan is important. Again, this is a retrospective study in which timing could not be controlled. The letter writers do not give their source of information as to why they think timing is important.

References

1. Zuccoli G, Panigrahy A, Bailey A, et al. Redefining the Guillain-Barré spectrum in children: neuroimaging findings of cranial nerve involvement. AJNR Am J Neuroradiol 2011 Feb 3. [Epub ahead of print]
2. Roodbol J, de Wit MC, Walgaard C, et al. Recognizing Guillain-Barré syndrome in preschool children. Neurology2011 1;76:807–10[Abstract/Free Full Text]
3. Korinthenberg R, Schessl J, Kirschner J. Clinical presentation and course of childhood Guillain-Barré syndrome: a prospective multicentre study. Neuropediatrics 2007;38:10–17[CrossRef][Medline]
4. Rabie M, Nevo Y. Childhood acute and chronic immune-mediated polyradiculoneuropathies. Eur J Paediatr Neurol2009;13:209–18. Epub 2008 Jun 26[CrossRef][Medline]
5. van Doorn PA, Ruts L, Jacobs BC. Clinical features, pathogenesis, and treatment of Guillain-Barré syndrome.Lancet Neurol 2008;7:939–50[CrossRef][Medline]
6. Smith N, Pereira J, Grattan-Smith PJ. Investigation of suspected Guillain-Barré syndrome in childhood: what is the role for gadolinium-enhanced magnetic resonance imaging of the spine? Paediatr Child Health 2010 Jul 2. [Epub ahead of print]