Rehabilitation of facial nerve palsy combining neuromuscular retraining and botulinum toxin A injection: a tertiary referral centre experience and a new working protocol proposal

Purpose: Neuromuscular retraining (NMR) is the primary treatment for synkinesis in facial nerve palsy (FNP) patients, with botulinum toxin type A (BTX-A) enhancing rehabilitation outcomes. This study aims to assess the functional outcomes of combining BTX-A infiltration and NMR in treating synkinesis in peripheral FNP patients. Materials and methods: This retrospective study, conducted at the University Hospital of Modena (2020–2023), included patients with chronic peripheral FNP treated with NMR and at least two BTX-A injections for synkinesis. The degree of paralysis was assessed using the Sunnybrook classification system before and after BTX-A injections. Results: The study included 140 patients, with FNP causes categorized as iatrogenic (46%), idiopathic (38%), infective (10%), and post-traumatic (5.3%). The median time between paralysis onset and first BTX-A injection was 19.3 months, with an average of 15.68 IU per injection session. The most commonly treated muscles for synkinesis were the platysma, mentalis, orbicularis oculi, orbicularis oris, and levator labii superioris alaeque nasi on the affected side. For facial symmetry, the frontalis, zygomatic, depressor labii inferioris, and depressor anguli oris muscles on the healthy side were treated. Following two BTX-A injections, the Sunnybrook score improved by a mean of 11.76 points, and the synkinesis score decreased by 4.78 points (both statistically significant, p < 0.05). Conclusion: BTX-A is an effective treatment for reducing synkinesis and improving facial function in chronic FNP. When combined with consistent rehabilitation, it supports the resumption of voluntary movement. NMR proves to be an essential adjunctive therapy in enhancing the outcomes of BTX-A treatment.