Facial electroneuronography in bell’s palsy : comparison between interpretation methods

الملخص EN

Aim of work: To study the electroneuronographic changes in acute Bell's palsy from upper, middle and lower face in order to find out the most efficacious method for assessment of the progress of the paralysis and to compare the 2 methods of calculating electroneuronography (ENoG).

In the first the amplitude of the compound muscle action potential (CMAP) of the paralyzed side was compared to that of the healthy side of the patient and a percent was recorded.

In the second method the ENoG was calculated by comparing the amplitude of CMAP of the paralyzed side of the patient to the mean amplitude of CMAP of the control group and a percent was recorded to be used in patients with bilateral facial paralysis.

Materials & Methods: Our study was conducted on thirty patients who presented with Bell's palsy within the first 5 days of the onset (16 females and 14 males).

All of them were subjected to clinical grading and electroneuronographic assessment every other day for the first 2 weeks of onset then weekly up to 3 months or until recovery occurred.

The study also included 40 volunteer subjects matched for age and sex with the patients.

They were examined to determine a mean amplitude value of CMAP of the 3 examined muscles (orbicularis oculi, Nasal alae and Orbicularis oris muscles).

Results: The control group showed that the recorded amplitude of CMAP of the three examined muscles showed: non-significant difference as regards the right and left sides, male and female groups.

On comparing the mean amplitude of CMAP of the control group with the mean amplitude of CMAP of the healthy side of the patient group, we also found a non-significant difference.

On recalculating the ENoG in reference to this mean value of controls, we found no statistical difference between it and the ENoG calculated in reference to the healthy side of the patient himself.

However, we found that it is better to use the healthy side of the patient himself to calculate the ENoG as the data of the patient himself are more homogenous.

Our results showed a highly significant association between the recorded ENoG of the 3 examined muscles at presentation and at follow-up with no predilection of paralysis to any one of them.

However, the ENoG over nasal alae muscle showed the most reliable value and the next was the orbicularis oris, then the orbicularis oculi muscle.

We also found that the clinical progress was accompanied by a progress in the percentage of ENoG and this was true for the 3 examined muscles.