Prognosis in Bell’s Palsy
July 1, 2002
Abstract & Commentary
Source: Kress BP, et al. Neuroradiology. 2002;44:428-433.
Can magnetic resonance imaging (MRI) of the seventh cranial nerve aid in prognosticating Bell’s palsy? To answer this question prospectively, gadolinium (GAD) enhanced MRI of 20 such patients was performed within 24 hours of diagnosis. Five segments of the facial nerve were identified, including those of the internal auditory canal, labyrinth, geniculate ganglion, tympanum, and mastoid. Five measurements were obtained for each site and a mean value, standard deviation, and coefficient of variation were calculated. All underwent lumbar puncture. Nerve conduction study (NCS) of the facial nerve was additionally performed in 18, with facial motor amplitude being compared side to side.
Among the 15 men and 5 women with idiopathic Bell’s palsy (mean age, 38 years), 15 were right sided and 5 were left sided. CSF protein was increased in 9 patients by a 4-time average. Seventeen patients improved within 1-2 weeks, while 3 remained unchanged or worsened. On NCS, these 3 demonstrated facial motor amplitude less than 20% compared to the normal side, a known indicator of poor prognosis. All 3 also demonstrated high MRI signal increases in all 5 segments of the facial nerve. Importantly, none of the patients with a good outcome had signal intensity increases > 100% in the distal 2 segments of the facial nerve (tympanic and mastoid portions). Improvement did not correlate with CSF protein level. Quantitative MRI appears to provide prognostic information in Bell’s palsy.
Commentary
Cytokine levels, though elevated in Bell’s palsy, do not appear to be useful prognostically (J Neurol Sci. 2002;197:69-72). Serum levels of IL-6, IL-8, IL-1b, IL-2r, and tumor necrosis factor alpha (TNF-alpha) were assayed in 23 patients with Bell’s palsy and compared to those of 30 healthy controls. Patient’s serum was obtained between 2-30 days following onset of facial weakness. Both patients and controls had similar IL-1b and IL-2r levels, whereas IL-6, IL-8, and TNF-alpha levels were significantly higher in the former (P < 0.05). Although cytokines appear to be produced in Bell’s palsy and may play a role in pathogenesis, no correlation was found between recovery and serum cytokine level. —Michael Rubin
Dr. Rubin, Professor of Clinical Neurology, New York Presbyterian Hospital-Cornell Campus, is Assistant Editor of Neurology Alert.
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