DISCUSIÓN

Application of botulinum toxin a for the treatment of Frey’s syndrome

Aplicación de la toxina botulínica a para el tratamiento del síndrome de Frey

Luis Antonio Sánchez Cuellar

Médico Adjunto. Servicio de Cirugía Oral y Maxilofacial. Hospital Universitario Río Hortega. Valladolid. España

There are many unanswered questions about Frey’s syndrome. The etiology, pathogenesis, and treatment of Frey’s syndrome are controversial. These considerations are discussed in the preceding article, in which the authors review what is known about the disorder and discuss therapeutic modalities.^1-3

No definitive and effective treatment for Frey’s syndrome is available. Often, advising the patient about the possibility that Frey’s syndrome may occur and reassuring him/her about its consequences may give the patient relief when the clinical manifestations are mild. The main discomfort referred is related to the appearance of symptoms in public, which can cause disability and social isolation.

Once the syndrome is established, surgical treatment rarely is used. The therapeutic modality that produces the best results and has the most promising future is botulinum toxin, which is why the study discussed here is relevant.⁴ Studies of botulinum toxin are important for establishing specific administration and dosage guidelines. In such studies, it is advisable to use systems to enhance the objectivity of the evaluation of results: use of the healthy side of the face as the control, exact measurement of the area involved using a millimeter grid, and assessing the severity of the syndrome (Luna-Ortiz table) to modify the dose in accordance with the severity of the condition.⁵

At the XVII International Symposium of Head and Neck Surgeons held in San Sebastián in 1990, Dr. Gómez Montoya presented a communication on the treatment of facial paralysis sequelae after parotid surgery. The intervention was very short: «there should be no sequelae, but if the facial nerve is injured, it must be treated and corrected in the same surgical act». This categorical affirmation is not applicable to Frey’s syndrome, but the underlying attitude is: in the course of the intervention, we should try to use the necessary techniques to try to keep the syndrome from occurring.

Surgical treatment can be prophylactic at the time parotidectomy is performed and therapeutic after the syndrome has appeared. The most widely accepted therapy is the superficial musculo-aponeurotic system (SMAS) flap. The fascial tissue blocks the anastomosis of the postganglionic parasympathetic fibers of the parotid with the sympathetic postganglionic fibers of the sweat glands. The SMAS flap improves the soft tissue defect (for some authors it acts as a membrane that guides tissue regeneration) and has evident functional effects since it reduces the incidence of Frey’s syndrome. Many studies have confirmed these results.^6-8

Almost all surgical treatments attempt to achieve this barrier effect by interposing tissues between the parotid parenchyma and the subcutaneous tissue. Flaps of sternocleidomastoid muscle rotation, platysma, cervical fascia, temporoparietal fascia, fascia lata, freeze-dried dura mater, abdominal dermoadipose grafts, membranes of polyactic acid, poly(tetrafluoroethylene), and alloderm (acellular dermis from which the cells are eliminated and the bioactive skin matrix is conserved) all have been used . However, of all of these materials, the best results are obtained with the SMAS flap. The SMAS flap does not required enlarged incisions, cause donor area morbidity, excessively prolong operating time, or increase costs. The procedure sometimes cannot be performed, particularly in the case of malignant tumors, because it might compromise the resection margins.

Diverse studies have correlated the incidence of Frey’s syndrome and facial nerve dysfunction with the amount of parotid tissue resected: in more enlarged and radical parotidectomies, the morbidity increases.⁹ The tendency is to seek functional glandular surgery, perform less radical resections, and excise as little healthy glandular tissue as possible in order to cure the disease and avoid recurrence. The residual glandular tissue must be functional. Reducing the amount of glandular tissue sacrificed diminishes surgical morbidity: disfiguring scars, facial paresis, and Frey’s syndrome.

Following these criteria, various surgical procedures can make it possible to achieve these objectives and, consequently, reduce the number of patients with Frey’s syndrome. In benign tumor pathology, a growing number of authors recommend partial or limited superficial parotidectomy (also known as subtotal or almost total parotidectomy).^10,11 In tumors of the deep lobe, selective techniques are used to conserve the superficial lobe.^12,13 In specific cases, some authors defend limited enucleation, tumorectomy, and extracapsular dissection techniques.¹⁴ Controversy also exists regarding the resection margins in the case of pleomorphic adenoma,⁹ the most frequent cause of parotidectomy. Various studies have drawn the conclusion that conservative superficial parotidectomy is unnecessary or excessive in many cases.

Therefore, surgical techniques should be used preventively, whereas botulinum toxin A might be the treatment of choice for the established syndrome.

References

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