Prognostic value of electroneurography in Bell’s palsy andRamsay–Hunt’s syndrome

Lee, D.-H., Chae, S.-Y., Park, Y.-S., & Yeo, S.-W.

Department of Otolaryngology – Head and Neck Surgery, College of Medicine, The Catholic University of Korea,

Seoul, South Korea

Accepted 29 December 2005

Clin. Otolaryngol 2006, 31, 144–148

Objectives: This study evaluated the accuracy of electro-

neurography to predict the prognosis of Bell’s palsy and

Ramsay–Hunt’s syndrome.

Design: A retrospective, institutional review board-

approved study.

Setting: A secondary referral and a university-based

centre.

Participants: The patients had been treated for a sudden

onset unilateral facial paralysis over the past 10 years

(1994–2004). This retrospective study included only those

patients who had been followed up for at least 3 months

or if they had reached a complete recovery before then.

Main outcomes measures: House–Backmann grade versus

electroneurography value.

Results: The recovery rates to House–Brackmann grade II

or better were 95% in those with Bell’s palsy and 84% in

those with herpes zoster oticus. The electroneurography

value of the recovery and non-recovery groups from

those with either Bell’s palsy or herpes zoster oticus was

similar. The logistic regression model between the electro-

neurography values and the probability of recovery

showed no correlation in those with Bell’s palsy or with

herpes zoster oticus. This study did not identify the

proper electroneurography value that had enough appro-

priate sensitivity and specificity to predict the prognosis

of paralysis accurately in Bell’s palsy or in herpes zoster

oticus patients.

Conclusion: Electroneurography performed between

day 7 and 10 for Bell’s palsy or day 10 and 14 for

herpes zoster oticus does not provide accurate

information on the prognosis or recovery rate of the

facial paralysis.

Acute peripheral facial paralysis is a rare disease in oto-

laryngology, with an estimated incidence of �30 patients

per 100 000 populations annually. Facial paralysis is an

extremely frightening situation for patients. It can cause

extreme stress as a result of the obvious disfiguring

facial expression, which may cause significant functional,

aesthetic, and psychological disturbances to the patient.

Because the psychological stress of patients with acute

facial palsy is generally high on the first hospital visit,

the questions most frequently asked by these patients

are whether or not their facial function will return to

normal, how much of their facial function will be recov-

ered, and how long is this going to take, suggesting that

clinicians must also treat the psychological aspects of

this manifestation by adequately explaining the progno-

sis, in addition to providing the appropriate medical

therapy.

For decades, physicians have searched for prognostic

tests of sufficient accuracy to serve the obvious need for

information. Since the early 1970s when Esslen1 introduced

the use of electroneurography, prognostication has been

based mainly on various electrophysiologic tests, including

the nerve excitability test, the maximal stimulation test,

and electromyography. In particular, electroneuro-

graphy can determine the percentage of fibres that have

degenerated, and various studies have shown that electro-

neurography can be used to predict the prognosis of acute

facial palsy,2–7 and May et al.8 reported that degeneration

£25% within the first 2 weeks of onset indicated a satisfac-

tory restoration of the facial function in 98% of Bell’s palsy

patients. However, these studies targeted only those with

Bell’s palsy or traumatic palsy, and did not include those

with herpes zoster oticus, which is the second most com-

mon cause of facial paralysis. In addition, they did not

report the subdivided prognostic profiles in the case of

degeneration not exceeding 25% within the first 2 weeks of

onset.

Correspondence: Dr D.-H Lee, Department of Otolaryngology – Head

and Neck Surgery, The Catholic University of Korea, Uijeongbu

St Mary’s Hospital, 65–1 Gumoh-Dong, Uijeongbu City, Gyeonggi-Do,

480–130, South Korea, Tel.: 82-31-820-3564; fax: 82-31-847-0038;

e-mail: leedh0814@catholic.ac.kr

OR

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144 � 2006 The Authors. Journal compilation � 2006 Blackwell Publishing Limited, Clinical Otolaryngology, 31, 144–148

The aims of this study in patients with Bell’s palsy and

Ramsay–Hunt’s syndrome were: (1) to evaluate the corre-

lation between the electroneurography results and the

prognosis; and (2) to determine the validity of electro-

neurography as a prognostic indicator.

Subjects and methods

Patients inclusion

This study enrolled patients treated for a sudden onset

unilateral facial paralysis between 1994 and 2004 at the

Otolaryngology – Head and Neck Surgery Department in

Uijeongbu St Mary’s Hospital, which is a secondary refer-

ral and a university-based centre. The medical records of

these patients were screened retrospectively. A diagnosis

of Bell’s palsy and herpes zoster oticus was confirmed by

a clinical examination, blood laboratory tests including

those for the herpes zoster virus and radiological studies

including magnetic resonance imaging. Patients with

facial paralysis resulting from other causes were excluded.

This retrospective study included only those patients who

could be followed up for at least 3 months or if they had

reached a complete recovery before then.

House–Brackmann grading

The status of the facial nerve function was documented

using the House–Brackmann grading system (Table 1).9

The ‘initial status’ was defined as the worst House–Brack-

mann grade after the facial paralysis had developed, and

the ‘last status’ was defined as the House–Brackmann

grade at the time of either complete recovery or the

patient’s final visit. The ‘degree of recovery’ was defined

as the difference between the initial and final status.

Those patients whose final status was less than the initial

status were grouped into the ‘recovery group’ and those

patients whose final status was House–Brackmann grade I

were classified into the ‘complete-recovery group’.

Electroneurography

The electroneurography was performed 7–10 days after

onset in the Bell’s palsy patients and 10–14 days after

onset in the herpes zoster oticus patients. The percent-

age of fibres remaining was calculated by dividing the

amplitude of the compound action potential of the

paralysed side by that of the normal side, multiplied by

100.

Table 1. House–Brackmann facial nerve grading system

Grade Defined by

1 Normal Normal facial function in all areas

2 Mild dysfunction Slight weakness noticeable only on close inspection

At rest: normal symmetry of forehead, ability to close eye with minimal effort and slight

asymmetry, ability to move corners of mouth with maximal effort and slight asymmetry

No synkinesis, contracture, or hemifacial spasm

3 Moderate dysfunction Obvious but not disfiguring difference between two sides, no functional impairment;

noticeable but not severe synkinesis, contracture, and/or hemifacial spasm

At rest: normal symmetry and tone. Motion: slight to no movement of forehead,

ability to close eye with maximal effort and obvious asymmetry, ability to move

corners of mouth with maximal effort and obvious asymmetry

Patients who have obvious but not disfiguring synkinesis, contracture, and/or

hemifacial spasm are grade III regardless of degree of motor activity

4 Moderately severe dysfunction Obvious weakness and/or disfiguring asymmetry

At rest: normal symmetry and tone. Motion: no movement of forehead; inability to close

eye completely with maximal effort.

Patients with synkinesis, mass action, and/or hemifacial spasm severe enough to

interfere with function are grade IV regardless of motor activity

5 Severe dysfunction Only barely perceptible motion

At rest: possible asymmetry with droop of corner of mouth and decreased or absence of nasal

labial fold

Motion: no movement of forehead, incomplete closure of eye and only slight movement of lid

with maximal effort, slight movement of corner of mouth

Synkinesis, contracture, and hemifacial spasm usually absent

6 Total paralysis Loss of tone; asymmetry; no motion; no synkinesis, contracture, or hemifacial spasm

ENoG in peripheral facial palsy 145

� 2006 The Authors. Journal compilation � 2006 Blackwell Publishing Limited, Clinical Otolaryngology, 31, 144–148

Treatment protocol

Uniform treatments were given to all patients diagnosed

with either Bell’s palsy or herpes zoster oticus, and they

were admitted for 10 days. The treatments given to the

patients were physical and psychological rest; low-salt and

high-protein diets; carbogen therapy; protective eye care

including the application of artificial eye drops for day-

time use and eye ointment for nighttime; the use of adhe-

sive tape to close the paralysed eyelid during sleep;

stellate ganglion block therapy, and exercise to maintain

the tone of the facial muscles by physical therapy. The

medical treatments consisted of high-dose prednisolone

and peripheral vasodilators orally, in combination with

dextran intravenously. Acyclovir i.v. was administered to

the herpes zoster oticus patients. The prednisolone dose

was 1 mg/kg body weight per a day for 5 days. There-

after, the dose was tapered for further 5 days. The acyclo-

vir dose was 5 mg/kg body weight every 8 h for 5 days.

Afterward, acyclovir was administered orally at a dose of

400 mg t.i.d. for a further 7 days.

Statistical analysis

The data in this study are reported as a mean ± SD. All

the statistical analyses were performed using the spss

software program (SPSS Inc., Chicago, IL, USA), and a

P-value < 0.05 was considered significant.

Ethical considerations

Institutional review board approval of Uijeongbu St

Mary’s Hospital was obtained for this study. Patient

informed consent was not required by the institutional

review board.

Results

Bell’s palsy

Patients. During the study period, 110 Bell’s palsy

patients were admitted for treatment. The patients who

were lost after discharge were excluded and 55 Bell’s

palsy patients met the inclusion criteria. There was no

significant difference of initial status between admission

group (110 patients) and study group (55 patients)

(chi-square test; P ¼ 0.32). All of Bell’s palsy patients

had magnetic resonance imaging performed to rule out

other causative lesions. Electroneurography was per-

formed in 40 patients. The Bell’s palsy group consisted

of 17 males and 23 females with a mean age of

36.4 years (SD, 18.2 years). The right and left side were

involved in 28 and 12 patients, respectively. There was

no significant difference of initial and final status

between total group and electroneurography group (chi-

square test; P ¼ 0.74). Table 2a shows the initial and

final status of the Bell’s palsy. The chance of a complete

recovery was estimated to be 53% in the Bell’s palsy

group (Fig. 1a).

Correlation between the House–Brackmann grade and elec-

troneurography value. A Mann–Whitney test was used to

analyse the difference in the electroneurography value

according to whether or not there was a recovery. In the

Bell’s palsy group, the electroneurography value of

the recovery and non-recovery groups was similar (P ¼0.84). In addition, the complete recovery and non-com-

plete recovery groups had comparable electroneurography

values (P ¼ 0.32).

Logistic regression analysis was used to evaluate the

relationships between the electroneurography value and

whether or not there was a recovery, and between the

electroneurography value and whether or not the recovery

was complete. In the Bell’s palsy group, there was no sig-

nificant correlation between the electroneurography value

and whether or not there was a recovery, as well as

between the electroneurography value and whether or not

the recovery was complete (P ¼ 0.85 and P ¼ 0.75,

respectively).

Capability of the electroneurography value to accurately pre-

dict the prognosis of peripheral facial palsy. The sensitivity

and specificity was calculated on the basis of the sup-

Table 2. The initial and final House–Brackmann grades of the

(a) Bell’s palsy (n ¼ 40), and (b) herpes zoster oticus groups

(n ¼ 19)

Final grade

Initial grade

II III IV V

(a)

I 1 12 6 2

II 3 8 6

III

IV 1

V 1

(b)

I 1 5 3

II 1 3 3

III 1 1

IV 1

V

146 D.-H. Lee et al

� 2006 The Authors. Journal compilation � 2006 Blackwell Publishing Limited, Clinical Otolaryngology, 31, 144–148

posed electroneurography values to assess the capability

of the electroneurography value to accurately predict the

prognosis of facial paralysis (Table 3). When calculated

based on electroneurography values of 90%, 80%, 70%,

60% and 50%, their sensitivities in Bell’s palsy were the

same, 90%, and their specificities were £50%. Therefore,

we could not select the proper electroneurography value

that had enough appropriate sensitivity and specificity to

predict the prognosis of facial paralysis accurately in the

Bell’s palsy patients.

Herpes zoster oticus

Patients. During the study period, 29 herpes zoster oticus

patients were admitted for treatment. The patients who

were lost after discharge were excluded and 26 herpes

zoster oticus patients met the inclusion criteria. Electro-

neurography was performed in 19 patients. The herpes

zoster oticus group consisted of 12 males and seven

females with a mean age of 40.3 years (SD, 21.7 years).

The right and left side were involved in 13 and six

patients, respectively. There was no significant difference

of initial and final status between total group and electro-

neurography group (chi-square test; P ¼ 0.83). Table 2b

shows the initial and final status of the herpes zoster oti-

cus group. The chance of a complete recovery was esti-

mated to be 47% in the herpes zoster oticus group

(Fig. 1b).

Correlation between the House–Brackmann grade and

electroneurography value. A Mann–Whitney test was used

to analyse the difference in the electroneurography value

according to whether or not there was a recovery. In the

herpes zoster oticus group, there were no differences in the

electroneurography value between the recovery and non-

recovery groups (P ¼ 0.14), and between the complete

recovery and non-complete recovery groups (P ¼ 0.78).

Logistic regression analysis was used to evaluate the

relationships between the electroneurography value and

whether or not there was a recovery, and between the

electroneurography value and whether or not the recovery

was complete. In the herpes zoster oticus group, there

were no significant correlation between the electroneuro-

graphy value and whether or not there was a recov-

ery, and no correlation between the electroneurography

value and whether or not the recovery was complete

(P ¼ 0.19 and P ¼ 0.82, respectively).

Capability of the electroneurography value to accurately pre-

dict the prognosis of peripheral facial palsy. The sensitivity

and specificity was calculated on the basis of the sup-

posed electroneurography values to assess the capability

of the electroneurography value to accurately predict the

prognosis of facial paralysis (Table 3). When calculated

based on electroneurography values of 90% and 80%,

their sensitivities in the herpes zoster oticus patients were

the same, 90%, but their specificities were £1/3. There-

fore, we could not select the proper electroneurography

Fig. 1. Recovery status of facial paralysis versus electroneurogra-

phy ratio. (a) Bell’s palsy; and (b) herpes zoster oticus groups.

1, completely recovered; 0, not recovered.

Table 3. Sensitivity and specificity of electroneurography in

predicting a complete recovery in Bell’s palsy and herpes zoster

oticus

ENoG (%)

Bell’s palsy Herpes zoster oticus

Sensitivity Specificity Sensitivity Specificity

90 0.0 89.5 22.2 90.0

80 4.8 89.5 33.3 90.0

70 9.5 89.5 33.3 80.0

60 28.6 89.5 44.4 60.0

50 42.9 89.5 55.6 30.0

40 52.4 73.7 55.6 30.0

30 66.7 47.7 77.8 20.0

20 76.2 21.1 88.9 20.0

10 100.0 0.0 100.0 10.0

ENoG in peripheral facial palsy 147

� 2006 The Authors. Journal compilation � 2006 Blackwell Publishing Limited, Clinical Otolaryngology, 31, 144–148

value that had enough appropriate sensitivity and specif-

icity to predict the prognosis of facial paralysis accurately

in the herpes zoster oticus patients.

Discussion

Strengths of the study

May et al.8 reported that if an electroneurography of 25%

or higher is maintained up to the 10th day after onset, a

patient with Bell’s palsy has a 98% chance of achieving a

satisfactory recovery. If an electroneurography of 11–24%

remains, the patient has an 84% chance of achieving a

satisfactory recovery. However, if an electroneurography

of 10% or less remains, the patient has only a 21%

chance of achieving a satisfactory recovery. However,

many cases which did not follow these relations have

resulted in the clinician’s confusion and patient’s anxiety.

In addition, these criteria are not suitable for facial para-

lysis other than Bell’s palsy. Especially, in the herpes zos-

ter oticus, the progress of degeneration is not constant

over time, and there are few reports on its course and

prognosis. This was the first study which evaluated the

correlation between the electroneurography results and

the prognosis in the herpes zoster oticus.

Limitations of the study

This study has three limitations. One limitation was the

limited number of cases, especially, the number of herpes

zoster oticus patients was too small. The other was the

short period of the follow up. This study was a retrospec-

tive study and included only those patients who could be

followed up for at least 3 months or until they had

reached a complete recovery. For the nature of the facial

paralysis, the more long-term follow up might yield the

better results. Lastly, too much Bell’s palsy patients were

lost. Although there was no significant difference of initial

status between 110 patients who were admitted and 55

patients who met the inclusion criteria, these missing data

might be a considerable source of bias.

Comparison with other studies

These results were different from those reported by

Chow,7 who noted that Bell’s palsy patients with electro-

neurography values £72.63% had a ‡90% chance of

recovery to House–Brackmann grade II or better within

2 months. He also noted that the sensitivity and specifici-

ty of electroneurography in predicting a good prognosis

in patients with Bell’s palsy were 82% and 100%, respect-

ively.

Conclusion

In conclusion, the electroneurography value performed

between day 7 and 10 for Bell’s palsy or day 10 and 14

for herpes zoster oticus is not a precise prognostic indica-

tor. The clinical implications of its use are possibly to

counsel and relieve the patients’ psychosocial distress.

However, it is not accurate or reliable enough to deter-

mine the prognosis of facial paralysis quantitatively.

Conflict of interest

None declared.

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