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Letters and Responses |
Clinical Director, Facial Rehabilitation Services Eagle Physical Therapy Mars Professional Building Pittsburgh St, Suite 101 PO Box 1095 Mars, PA 16046-1095
Kudos to Ms Brach and Dr VanSwearingen for their fine case study on the use of facial neuromuscular retraining in treating a patient with Bell's palsy (April 1999). I am concerned as to the unfortunate decision to use the term "Bell palsy" rather than "Bell's palsy" throughout the article. To quote Larry Lundy, MD, of the Mayo Clinic, Jacksonville, who presented a lecture, "Clinical Evaluation of Acute Facial Palsies" at the American Academy of Otolaryngology-Head and Neck Surgery Foundation's Conference on Facial Nerve Disorders in Washington, DC, in March 1999: "The most common type of acute facial palsy is Bell's palsy, aka, idiopathic facial palsy or herpes simplex facial palsy." Bell's palsy was extensively discussed at this meeting, in which I was an invited panelist, but no one called it "Bell palsy." Also, you will not easily find the use of the term "Bell palsy" in a literature review. (However, to weaken my argument, I have included one in my references. The irony does not escape me.)
The authors state that Bell's palsy is of unknown etiology. That is certainly what "idiopathic" infers. In the last few years, however, there has been much research published concluding that the cause is viral. Bauer and Coker stated, "aided by developments in molecular biology techniques, an increasing number of investigators have reported evidence for a viral etiology in many cases of ‘idiopathic’ facial paralysis."1 Adour and associates concluded that "sufficient clinical, laboratory, magnetic resonance imaging, and pathology data have accumulated to add veracity to the hypothesis that herpes simplex causes Bell's palsy."2 I conclude with 3 studies done by Naoaki Yanagihara, MD, and associates in Japan, who have published strong research evidence for herpes simplex virus as the causative agent of Bell's palsy.3–5
Bell's palsy is a diagnosis of exclusion.6 Some 80 to 100 other known causes of facial paralysis (mostly rare) have been identified, although Bell's palsy is the most common. For example, herpes zoster oticus (also known as Ramsay Hunt syndrome) is often mistaken for it. Herpes zoster oticus has a similar presentation, but is characterized by significant pain, particularly periauricular, and the presence of vesicles in the ear canal or externally. Usually, the recovery process is longer and less complete.
To conclude, Bell's palsy is no longer considered idiopathic, and physicians who are setting the standards of care today therefore recommend treatment with an antiviral medicine during the acute stage. To call this condition "Bell palsy" is akin to an ostrich putting its head in the sand...you can do it due to an editorial policy, but you will not be with the great majority of the rest of the medical community.
References
Department of Physical Therapy University of Pittsburgh 6035 Forbes Tower Pittsburgh, PA 15260 (jessievs+{at}pitt.edu)
We thank Mr Henkelmann for his interest in the case reported and our understanding of the disorder. An explanation for the terminology ("Bell palsy") is in order, and a brief review of the reported evidence indicates why the argument for viral causation of Bell palsy is incomplete and unacceptable.
The use of the term "Bell palsy" instead of "Bell's palsy" was the recommendation of the Editor, in accordance with the current American Medical Association (AMA) guidelines for eponyms.1 Based on the AMA guidelines, the possessive ending should be dropped from eponyms. According to the AMA guidelines, "there is continuing debate over the use of the possessive form; however, a transition toward the nonpossessive form may be gradually taking place.1(p470) Our response as authors to the edit of "Bell's palsy" to "Bell palsy" was to cite the current usage in Dorland's Illustrated Medical Dictionary, 28th edition, which indicates "Bell's palsy" as the acceptable terminology.2 We requested an exception to the guidelines for eponyms to allow the use of "Bell's palsy." In not accepting our request, the Editor acted as an editor, conforming to the AMA guidelines and assuring that Physical Therapy is consistent with the format of other reputable biomedical journals. We respect the decision.
The assertion that the cause of Bell palsy has been demonstrated in recent research reports to be viral, particularly herpes simplex virus (HSV), cannot be supported. Neither the references cited by Mr Henkelmann3–8 nor others provide evidence that HSV causes Bell palsy. Bauer and Coker,3 reviewing the evidence for an HSV etiology for Bell palsy, stated that the serologic evidence is variable. In human studies, seroconversion to HSV ranged from 0 to 15.6% of the cases of Bell palsy. The 15.6% seroconversion rate was reported for a sample of 45 patients with Bell palsy.4 Among a larger sample of patients with Bell palsy, seroconversion to HSV was documented in only 165 of 1,850 patients (8.9%).9 In 2 animal studies,7,10 seroconversion to HSV followed perineural injection of HSV, consistent with a causal hypothesis. In one of the studies, however, none of the animals developed facial paralysis.10
Evidence for a virally induced origin for Bell palsy has also been based on isolation of HSV from specimens of the facial nerve retrieved during decompression surgery to relieve the symptoms.6 The evidence for HSV is limited, as only 14 of 170 individuals with Bell palsy underwent the decompression surgery, and HSV was isolated in a subset of the surgical cases.6 The evidence for causation fails because HSV has also been isolated from over 70% of geniculate and trigeminal ganglia of 8 random autopsy specimens recovered from cadavers of adults who did not have Bell palsy.11
Although Adour et al4 concluded that HSV is the cause of Bell palsy, the evidence for the specific viral origin remains variable. In 1996, Adour et al4 reported better recovery among patients with Bell palsy given antiviral treatment compared with anti-inflammatory treatment in a randomized controlled clinical trial. More recently, De Diego et al12 reported the opposite finding, that is, a better outcome for patients with Bell palsy who are treated with an anti-inflammatory drug compared with those treated with the antiviral medication in a prospective randomized controlled clinical trial.
Epidemiologists apply several concepts to determine causal relations: strength, consistency and specificity of association, temporal sequence of events and dose response, and experimental evidence.13 The argument for HSV as causal for Bell palsy is weak. Herpes simplex virus is (1) present in 15.6% or fewer of cases, (2) present in individuals who do not have the facial paralysis of Bell palsy, (3) present in equal titers among individuals with and without Bell palsy, (4) associated with facial paralysis in only some of the cases in which HSV has been experimentally induced within the animal, and (5) variably associated with better outcomes in randomized controlled clinical trials of medical interventions.
We appreciate the interest in assuring the accuracy of the information shared and the review of literature provided by Mr Henkelmann. Discussions with peers and even among noted panelists on a topic are valuable; however, we are reminded that the discussions are not a substitute for careful review of the peer-reviewed literature when searching for evidence-based practice.
References
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