According to the searched literature there is insufficient evidence to support electrotherapy effectiveness when applied as a monotherapy, nor when combined with other procedures to treat Bell’s palsy. In recent studies on the use of electro-stimulation besides being insufficient, only one report, where electrotherapy was used alone, showed positive results when compared to the control not-treated group [
9]. These authors applied the procedure during 21 days after reconstructive surgery of the temporal muscle, showing that patients subjected to ES had better facial symmetry both static and dynamic, than the control groups. From the same study, due to the total segmentation of the facial nerve and its possible reconstruction, ES was applied to prevent muscular atrophy and to preserve completely the metabolic and contractile functioning, while waiting for neuronal regeneration [
9].
Most of the studies where ES was used to treat denervated muscles were performed on animals or in muscles bigger than facial muscles, such as the quadriceps, gastrocnemius and soleus; in addition, there is a lack of precision regarding the current type, duration and frequency of the stimuli that may favor better results or avoid greater damage [
18,
20]. Even so it is stated that if electrotherapy is used for denervated muscles, its application must begin as soon as facial reconstruction is done [
18].
In two other studies where massage therapy, ES and feedback exercises (FE) in front of a mirror were applied to individuals with different neuronal damage, greater benefit was found when ES and FE were used compared to massage therapy; 10 or no difference when ES plus FE vs FE alone were compared [
11] moreover, 29 subjects with neuropraxia from this last study completely recovered in one year without any treatment, i.e., ES was not used in addition to the FE therapy meaning that ES was not necessary. Feedback exercise and its benefits over the other treatments might be due to its selective recruitment on motor units observed during these exercises, and thus producing better control of facial movements. Electrostimulation/FE or FE alone have proven to be equally effective in other studies after neuromuscular learning, and retraining after traumatic or joint lesions [
5,
21,
22] Besides Dalla’s group findings [
10] Alakram and Puckree [
8] as well as Manikandan [
23] did not report benefits when comparing electrotherapy vs conventional or FE treatments. Alakram and Puckree8 found a higher recovery percentage when electrotherapy was added to the conventional treatment; however, due to the variance in the results no statistical significance was obtained (30 ± 12% vs 38 ± 18%, p=0.36). The main concerns in the Alakram and Puckree [
8] study are: 1) low number of participants per group (8 vs 8), 2) low number of electrotherapy sessions and scattered sessions (3 months, once a week), and 3) no control group, since it has been observed that conventional treatments, including just facial exercise could be successful [
1]. Moreover, when there is a control group the differences could be significant [
9]. In contrast, Manikandan [
23] reported that FE vs. conventional therapy plus electrotherapy gave better results in symmetry and facial movements control; however, it was not true to diminish synkinesis. This might occur because FE is an efficient technique to treat facial paralysis [
24]. Currently at least in Mexico, ES is applied in a general and unspecific way to improve mobility of facial muscles, although it is meant to only stimulate the paretic musculature in an uncontrolled manner; however, if ES is indiscriminately applied it is difficult to know its possible therapeutic role in the specific lesion’s site, since the facial nerve path is ramified. As a consequence of this possibility, it is not known whether stimulation of muscles before the contact of nerves to the facial region, such as the stylohyoid, the digastric or the auricular muscles, may generate a positive therapeutic response or to cause other impairments following the stimulation of different nerves. It is probable that ES if applied together, i.e., electromyography and electroneurography studies, and more specifically to restore or get facial expression and function back (such as mastication, blowing, blinking eyes, smiling, sucking, and others) even by stimulating secondary muscles such as the stylohyoid, the digastric or the auricular muscles, the benefits could improve. We conclude that ES alone or combined with other therapies gives no major benefits than conventional treatments for Bell’s paralysis, indeed, the benefits could be even lower.