Pre- and intra-operative prognostic factors of facial nerve function in cerebellopontine angle surgery.

PURPOSE: The study assesses whether pre- and intraoperative factors linked to electromyography and direct electrical stimulation (DES) of facial nerve can predict facial nerve function in the short- (12 days) and long-term (1 year) after cerebellopontine angle (CPA) tumor resection. METHODS: 157 patients who underwent surgical resection of CPA tumors with facial nerve monitoring. Pre-operative factors (age, tumor size, pure tone average), surgical time and intra-operative parameters regarding facial function, minimum stimulation threshold (MST), compound muscle action potential (CMAP) and the difference between proximal and distal CMAP (DPDC) were evaluated. RESULTS: A correlation between tumor size, MST, CMAP and facial function in both short and long term was found. A higher grade of immediate facial paralysis corresponded to a higher risk of poor outcome after one year. A postoperative House-Brackmann (HB) score of V or VI was correlated with poor outcome in 88.8% and 93.8% of cases. A risk of HB 3 or more, in the long term, was correlated with a tumor size of 20.2 mm. Using an MST of 0.1 mA, for long-term predictions, sensitivity and specificity were 0.62 (95% CI 0.46-0.75) and 0.73 (95% CI 0.61-0.82), respectively. With a CMAP cut-off < 200 µV, for long-term prediction, sensitivity was 0.73 (95% CI 0.53-0.87) and specificity 0.73 (95% CI 0.55-0.85). CONCLUSION: The assessment based on the cut-offs described increases the ability to predict facial function. Improving predictive accuracy enables surgeons to address patients' expectations and to establish an intervention timeline for planning facial reanimation.

Neurofibromatosis tipo 2 / Neurofibromatosis type 2

La neurofibromatosis tipo 2 es una enfermedad invalidante que se hereda de forma autosómica dominante. A menudo se ha confundido con la neurofibromatosis tipo 1, aunque son patologías distintas. Todos los sujetos que hereden una mutación en el gen de la neurofibromatosis tipo 2 (NF2), desarrollarán dicha enfermedad, caracterizada por el crecimiento de schwanomas, habitualmente vestibulares y de forma bilateral, así como meningiomas u otros tumores benignos del sistema nervioso central, antes de los 30 años de edad. Actualmente, podemos identificar la mutación del NF2 en la mayoría de las familias afectas. Hasta un 20% de los pacientes afectos de NF2 sin historia familiar, aparentemente casos esporádicos, son en realidad individuos con mosaicismo para esa mutación. La morbilidad de esos tumores es en gran medida debida a su tratamiento, que es principalmente quirúrgico. Cuando son pequeños, los schwanomas vestibulares se pueden resecar completamente con preservación tanto de la función auditiva como facial. En caso de tumores grandes se puede colocar un implante coclear o bien de tronco cerebral durante el mismo acto quirúrgico. Los principales factores pronósticos son: la edad media al diagnóstico, la presencia de meningiomas intracraneales y si el paciente fue tratado o no en un centro especializado (AU)

Type 2 neurofibromatosis (NF2) is an invalidating, inherited, dominant, autosomal disease. It is commonly confused with type 1 neurofibromatosis, although the two disorders are different. All subjects who inherit a mutated NF2 gene will develop the disease, which is characterised by the growth of schwannomas, generally affecting the vestibular nerve bilaterally, as well as meningiomas and other benign central nervous system tumours, before their third decade of life. It is currently possible to identify the NF2 mutation in most affected families. Up to about 20% of NF2 patients with no family history, apparently sporadic cases, are actually individuals with mosaicism for this mutation. Much of the morbidity from these tumours results from their treatment, which is primarily surgical. Small vestibular schwannomas can often be completely resected with preservation of both hearing and facial function. In case of large tumours it is possible to place a cochlear or brain stem implant during the schwannoma surgery. Age at diagnosis, the presence of intracranial meningiomas, and whether the patient was treated at a specialty centre or not, have been cited as the strongest prognostic factors (AU)

[Neurofibromatosis type 2]. / Neurofibromatosis tipo 2.

Type 2 neurofibromatosis (NF2) is an invalidating, inherited, dominant, autosomal disease. It is commonly confused with type 1 neurofibromatosis, although the two disorders are different. All subjects who inherit a mutated NF2 gene will develop the disease, which is characterised by the growth of schwannomas, generally affecting the vestibular nerve bilaterally, as well as meningiomas and other benign central nervous system tumours, before their third decade of life. It is currently possible to identify the NF2 mutation in most affected families. Up to about 20% of NF2 patients with no family history, apparently sporadic cases, are actually individuals with mosaicism for this mutation. Much of the morbidity from these tumours results from their treatment, which is primarily surgical. Small vestibular schwannomas can often be completely resected with preservation of both hearing and facial function. In case of large tumours it is possible to place a cochlear or brain stem implant during the schwannoma surgery. Age at diagnosis, the presence of intracranial meningiomas, and whether the patient was treated at a specialty centre or not, have been cited as the strongest prognostic factors.