Acute oropharyngeal palsy associated with anti-GM1b IgG antibody

Abstract

Sirs: Although patients with Guillain-Barre syndrome (GBS) typically show generalized muscle weakness with areflexia, a few patients have only regional weakness throughout the disease course. O’Leary et al. [4] described three patients who had rapid progression of localized oropharyngeal weakness with or without ataxia. Unlike typical GBS or Fisher syndrome, these patients never developed limb weakness, ophthalmoplegia, or ptosis; they were regarded as having a regional variant of GBS based on detection of anti-GQ1 b and anti-GT1 a IgG antibodies in serum. Another patient with acute oropharyngeal palsy also was reported to have these antibodies [5]. We treated a patient with acute oropharyngeal palsy associated with an isolated anti-GM1 b IgG antibody. This autoantibody has yet to be reported in patients with regional GBS variants, although in more generalized cases it is regarded as a diagnostic marker of GBS [3]. A 47-year-old woman’s voice developed an increasingly nasal quality over a few days. She had no history of a preceding cough, fever, sore throat or diarrhea. Neurological examination on day 5 of her course showed mild dysarthria and mild weakness of neck flexion (Medical Research Council grade, 4). Palatal elevation was diminished and the gag reflex was absent. Pupil size and reactions were normal. No signs of ophthalmoplegia, ptosis, or facial muscle weakness were found. Limb muscle power and tendon reflexes were normal. The patient could not perform tandem gait, but finger-to-nose and heel-to-knee tests were normal. The Romberg test was negative. No sensory or autonomic disturbances were present. The complete blood count and blood chemistry results were normal. Results of serological tests for Campylobacter jejuni, cytomegalovirus, Mycoplasma pneumoniae, varicella-zoster virus, and herpes simplex virus infections were negative. On day 7, serum IgG antibody titer against GM1 b was found to be elevated (1:2,000; normal, less than 1:500). No IgG antibodies against GM2, GM1, GD1 a, GalNAc-GD1 a, GD1b, GT1 a, GT1 b, or GQ1 b were detected. IgM antiganglioside antibodies were absent. Cerebrospinal fluid obtained on day 7 showed normal protein and cell content. Motor nerve conduction studies on day 7 were normal. A sensory nerve action potential was not evoked in the sural nerve, but sensory nerve action potentials and sensory conduction velocities were normal in the median nerve. Cranial MRI with enhancement was normal. From day 10, the patient was given intravenous immunoglobulin (400 mg/kg/day) for 5 consecutive days. She noted some difficulty in swallowing on day 11, but did not require tube feeding. Dysphagia and dysarthria respectively disappeared by days 14 and 28, and all other neurologic abnormalities had resolved completely 2 months after onset. The anti-GM1 b IgG antibody titer had returned to the normal range (less than 500) 8 months following onset of illness. Our patient experienced acute progression of oropharyngeal palsy as well as mild truncal ataxia and neck weakness. She never showed notable limb weakness, ophthalmoplegia, ptosis, or areflexia. These clinical features are simitar to those of O’Leary’s patients with acute oropharyngeal palsy [4]. However, these patients had antiGQ1 b and anti-GT1 a IgG antibodies, while our patient had an antiGM1 b IgG antibody. Anti-GM1 b antibody is closely related to severe limb weakness and slow recovery in generalized GBS [7]. On the whole, GBS patients with anti-GM1 b antibodies are somewhat less likely to have cranial nerve involvement, although this antibody can be detected in half of GBS patients who show oropharyngeal palsy as an initial symptom [2, 6]. Several case reports suggest that anti-GT1 a IgG antibody, with or without cross-reactivity with GQ1 b, is involved in the pathogenesis of oropharyngeal palsy in GBS [1]. Our case supports an association of oropharyngeal palsy with antiGM1 b antibodies. GQ1 b ganglioside in human cranial nerves is believed to be a target of the humoral autoimmune response in patients with Fisher syndrome or GBS with ophthalmoplegia and anti-GT1 a IgG antibody coexists in these conditions. AntiGQ1 b and anti-GT1 a IgG antibodies have also appeared together in acute ophthalmoparesis, Bickerstaff ’s brain stem encephalitis, and the pharyngeal-cervical-brachial variant of GBS [2]. In addition to anti-GT1 a and anti-GQ1 b antibodies, we feel that anti-GM1 b IgG antibody may be a helpful diagnostic marker for acute oropharyngeal palsy in some patients. Since in GBS anti-GT1 a, anti-GQ1 b, and anti-GM1 b IgG antibodies frequently coexist, acute oropharyngeal palsy may represent an early clinical stage of GBS, pharyngeal-cervical-brachial variant of LETTER TO THE EDITORS