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Show u s • t • » - Journal of Neuro- Ophthalmology 20( 1): 45^> 7, 2000. * • - > © 2000 Lippincott Williams & Wilkins, Inc., Philadelphia Magnetic Resonance Imaging Enhancement of Cranial Nerves in Inflammatory Bulbar Polyneuropathy Carolina do Val Ferreira, MD, Joel S. Glaser, MD, and Norman J. Schatz, MD A patient with generalized inflammatory polyneuropathy and facial diplegia was studied with magnetic resonance imaging. Multiple cranial nerves showed signal enhancement without sensory or motor dysfunction. Key Words: Bulbar polyneuropathy- Facial diplegia- Miller Fisher syndrome- Magnetic resonance imaging- Papilledema. Though not a single disorder- and arguably a continuum categorized by time course- acute, inflammatory demyelinating polyneuropathy may occur spontaneously, after bacterial or viral infection or uncomplicated surgical procedures, or postimmunization ( 1). This symptom complex may progress to severe bulbar paralysis and quadriplegia, or it may selectively involve facial and ocular muscle function, known as Miller Fisher syndrome. Bulbar signs may also be associated with more generalized disease ( Guillain- Barre syndrome; GBS). The annual incidence of GBS ranges from 0.4 to 2 cases per 100,000 people; men are more often affected than women, whites are more often affected than blacks ( 2), and the disease becomes more frequent with advancing age. Findings of elevated cerebrospinal fluid ( CSF) protein, autonomic dysfunction, facial diplegia, and electrophysiologic evidence of demyelinating neuropathy( l) substantiate the diagnosis. We present a patient with papilledema and facial diplegia whose magnetic resonance imaging ( MRI) revealed enhancement of multiple cranial nerves, but with paradoxically spared motor or sensory abnormalities. CASE REPORT A 24- year- old man developed cramping of his feet, hands, and buttocks, neck and lower back pain, and leg weakness 2 weeks after an upper respiratory infection. Weakness progressed within 1 week to quadriplegia, ar-reflexia, and facial diplegia, requiring assisted respira- Manuscript received October 19, 1998; accepted December 15, 1999. From the Fundacao Tecnico Educcional Souza Marques ( CdVF), Rio de Janiero, Brazil; and the Department of Ophthalmology, Cleveland Clinic Florida, Ft. Lauderdale, Florida, and the Bascom Palmer Eye Institute ( JSG, NJS), University of Miami, Miami, Florida. Address correspondence and reprint requests to Dr. Glaser, 4121 Crawford Avenue, Miami, FL 33133- 6160. tion. The patient's vision was blurred, and he could not close his eyes or move his face. Higher cortical function was preserved. The patient was treated with IV methyl-prednisolone, IV immunoglobulin, and plasmapheresis. Swallowing and respiration improved, permitting extu-bation, but quadriplegia persisted. On re- evaluation at 4 months, he still had blurred vision. Neuro- ophthalmic evaluation revealed extensive hemorrhagic papilledema; visual acuity of 20/ 30 OU, J1+ at near; 11 of 11 color plates identified; symmetric 5- mm pupils with brisk light reactions; and no afferent pupillary defect. Visual fields were full to confrontational techniques; automated perimetry could not be performed. Ocular rotations were full without nystagmus or ptosis. There was mild left exposure keratitis and bifacial weakness with incomplete closure of the left eye. Magnetic resonance imaging demonstrated bilateral enhancement of cranial nerves III, V, VI, and VII ( Figs. 1- 3). Remarkably, with the exception of facial diplegia, there was no clinical evidence of other cranial nerve malfunction. Cerebrospinal fluid opening pressure was 36- cm water, with a protein of 600 mg/ dL, glucose of 70mg/ dL, 3 red blood cell, and 0 white blood cell. Electromyography of peripheral nerves showed conduction block consistent with GBS. At 10 months, the patient continued to recover all motor function, with slight residual right facial weakness. No follow- up MRI has been performed. DISCUSSION Asbury et al. ( 3) first addressed the pathophysiology of idiopathic inflammatory cranial neuropathy in 1969, when they proposed that the polyneuritis syndrome is related to a lymphocyte- mediated autoimmune reaction. However, the patient studied by Grunnet and Lubow ( 4) showed central chromatolysis in the nuclei of the third, fourth, fifth, and twelfth nerves, and of the anterior horn cells, with only sparce lymphocytic infiltration. Three features characterize the pathology of GBS; inflammation, demyelination, and axonal degeneration in the peripheral nervous system. Central chromatolysis and degeneration of anterior horn cells and degeneration of spinal posterior columns are considered secondary to degeneration of peripheral motor and sensory axons ( 1). Inflammation may be the earliest pathologic change, with lymphocytes and macrophages predominating. However, in some recent studies ( 5), lymphocytic in- 45 46 C. DO VAL FERREIRA ET AL. FIG. 1. MRI; T- 1 weighted with gadolinium. Top: Axial section through midbrain with enhanced third nerves ( arrows). Middle: Coronal section corresponding to top axial section. Bottom: Entrance to cavernous sinuses. flammation has been relatively minor, and polymorphonuclear cells are scanty. Macrophages probably originate from both resident endoneurial macrophages and transformed circulating mononuclear cells, which appear to participate actively in the demyelinating process. Several theories are proposed to elucidate the pathologic mechanisms in inflammatory polyneuropathies. Observations include: activation of T- cells with increased circulating levels of soluble IL- 2 surface receptors; antimyelin antibodies; complement- fixing IgM; complement deposition on myelin sheaths and complement activation in both serum and CSF ( 1). Other evidence contrary to the autoimmune theories comes from examples of GBS in immunosuppressed patients, including in patients who have had renal transplantation ( 6). Endoneurial edema has been described in GBS nerves and nerve roots, although it was seldom seen by Asbury et al. ( 3) in their series of 19 autopsies. It is commonly seen in experimental allergic neuritis, where it is thought to result from diffusion of proteinaceous fluid through a leaky blood- nerve barrier. Similar leakage likely occurs in GBS and probably explains the elevated CSF protein level ( 1). The most common form of demyelination is apparently due to stripping of myelin by macrophages. Whether this is a primary process and how the macrophages are targeted to myelin sheath is not known. J Neuro- Ophrhalmol. Vol. 20. No. I. 2000 MRI ENHANCEMENT OF CRANIAL NERVES 47 r : • - » FIG. 2. MRI; T- 1 weighted with gadolinium. Axial section with enhancing fifth nerves ( arrows). Additionally, with light microscopy, Asbury et al. ( 3) noted evidence of axonal degeneration in 11 of 19 GBS autopsies, most prominent in cases with marked inflammation. In the Miller Fisher variant of inflammatory polyneuropathy, cranial nerve enhancement on MRI has been documented for the trochlear, ( 7) abducens, and oculo- FIG 3. MRI; T- 1 weighted with gadolinium. Top: Enhanced sixth nerves ( arrows) at exit from pons. Bottom: Enhanced sixth ( arrows) and seventh ( curved arrows) nerves. motor nerves ( 8). In those cases, appropriate external ophthalmoplegia was present, but not all ocular motor nerves demonstrated enhancement. The authors concluded that the lesions involved peripheral portions of the cranial nerves. Enhancement persisted at the 3- month follow- up in one case ( 7). In our patient, with the exception of facial diplegia, no other enhancing cranial nerves showed clinical deficits. Therefore, enhancement may not strictly infer demyeli-nation or conduction block, nor is demyelination the only possible pathophysiologic cause of enhancement. The inflammatory reaction may be minimal, only disrupting the blood- brain barrier. The elevated CSF protein may facilitate enhancement by physically coating basal neural structures, although selective enhancement only of cranial nerves is unexplained. Optic disc edema, though considered rare in GBS, is also well documented; it is attributed to optic nerve inflammation, or, more frequently, associated with intracranial hypertension. Morley and Reynolds ( 9) reviewed the reports of 27 published cases, to which they added another four cases, showing that the CSF protein concentration was quite variable, with considerable dissociation between the occurrence and course of papilledema and the dynamics of CSF protein levels. Other possibilities include absorption defects in the vesicular transport system of arachnoid villi, perhaps initiated by anomalous proteins ( 10). REFERENCES Feasby TE. Inflammatory- demyelinating polyneuropathies. Neurol Clin 1992; 10: 651- 61. Ropper A, Wijidicks E, Truax B. Guillain- Barre syndrome. Philadelphia: FA Davis, 1991. Asbury AK, Amason BG, Adams RD. The inflammatory lesion in idiopathic polyneuritis. Medicine 1969; 48: 173- 9. Grunnet ML, Lubow M. Ascending polyneuritis and ophthalmoplegia. Am J Ophthalmol 1972; 4: 1155- 72. Honaver M, Tharakan J, Hughes R. A clinicopathological study of Guillain- Barre syndrome. Brain 1991; 114: 1245- 52. Drachman D, Paterson P, Berlin B, et al. Immunosupression and the Guillain- Barre syndrome. Arch Neurol 1970; 23: 385- 9. Hideaki T, Nobuhiro Y, Koichi H. Trochlear nerve enhancement on three dimensional magnetic resonance imaging in Fisher syndrome. Am J Ophthalmol 1998; 126: 322^-. Nagaoka U, Kato T, Kurita K, et al. Cranial nerve enhancement on three dimensional MRI in Miller Fisher syndrome. Neurology 1996; 47: 1601- 2. Morley JB, Reynolds EH. Papilledema and Landry- Guillain- Barre syndrome. Brain 1966; 89: 205- 22. Fishman RA. Acute idiopathic polyneuritis ( GBS). In: Cerebrospinal fluid in diseases of the nervous system. Philadephia: Saud-ers, 1992: 333^ 12. » J Neuro- Ophthalmol. Vol. 20, No. I, 2000 |
