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Chirurgia della base del cranio laterale: 50 anni di impegno.La base del cranio non è anatomicamente divisa in anteriore e laterale, ma è per semplicità che comunemente si intendono i corridoi chirurgici con direzione antero-laterale, laterale pura e postero laterale come “Approcci chirurgici della base del cranio laterale”. Una relazione con titolo “Cinquant’anni di impegno”, di sforzo o di dedizione, vuole essere il riconoscimento a questa chirurgia che nel corso degli anni ha sviluppato interventi sempre più complessi con una morbidità sempre minore. Il principio della chirurgia della base del cranio laterale si fonda sulla possibilità di “fare spazio”, esporre adeguatamente, rimuovere osso per salvaguardare il cervello, insieme alla possibilità di preservare la funzione e adattare l’approccio chirurgico all’istologia della lesione. Il concetto che l’istologia detta l’entità della resezione chirurgica, bilanciando la morbidità intrinseca di ciascun approccio, è oggetto di trattazione nella prima sezione di questa relazione. Nella seconda sezione sono descritti i principali approcci chirurgici, intesi non come descrizione tecnica di ciascun tempo chirurgico, ma dei principi che sono alla base di ciascun approccio. La terza sezione è dedicata alle questioni aperte, quelle ancora irrisolte, inerenti alcuni tumori ed il loro trattamento. L’argomento del neurinoma sporadico dell’ottavo nervo cranico è trattato riportando l'attuale dibattito sulla osservazione, la chirurgia di preservazione dell’udito, la riabilitazione con l’impianto cocleare, la radioterapia e le ricerche recenti su marcatori tumorali predittivi di crescita. Il paraganglioma del forame giugulare è trattato nel contesto della chirurgia radicale, chirurgia parziale, osservazione e radioterapia. La terapia dei meningiomi della base del cranio analizza il punto di vista specifico dell’otochirurgo e del neurochirurgo. Cordomi e condrosarcomi, tumori del sacco endolinfatico, carcinomi dell’orecchio e colesteatoma della rocca sono le altre lesioni affrontate. Infine, nella quarta sezione è proposto un contributo a libera scelta ad autori di riconosciuta esperienza. Lo scopo di questa relazione è stato quello di fornire un aggiornamento della chirurgia della base del cranio laterale dopo 50 anni di duro lavoro e, o forse soprattutto, di permettere alle tante questioni irrisolte, alle domande che ancora non hanno risposta, di trovare espressione, affinchè il dibattito ed il progresso possano continuare con la condivisione di esperienze. Se al termine della lettura vi saranno più domande che risposte, potremo dirci che l’obiettivo di questa relazione è stato raggiunto.Disregarding the widely used division of skull base into anterior and lateral, since the skull base should be conceived as a single anatomic structure, it was to our convenience to group all those approaches that run from the antero-lateral, pure lateral and postero-lateral side of the skull base as “Surgery of the lateral skull base”. “50 years of endeavour” points to the great effort which has been made over the last decades, when more and more difficult surgeries were performed by reducing morbidity. The principle of lateral skull base surgery, “remove skull base bone to approach the base itself and the adjacent sites of the endo-esocranium”, was then combined with function preservation and with tailoring surgery to the pathology. The concept that histology dictates the extent of resection, balancing the intrinsic morbidity of each approach was the object of the first section of the present report. The main surgical approaches were described in the second section and were conceived not as a step-by-step description of technique, but as the highlighthening of the surgical principles. The third section was centered on open issues related to the tumor and its treatment. The topic of vestibular schwannoma was investigated with the current debate on observation, hearing preservation surgery, hearing rehabilitation, radiotherapy and the recent efforts to detect biological markers able to predict tumor growth. Jugular foramen paragangliomas were treated in the frame of radical or partial surgery, radiotherapy, partial “tailored” surgery and observation. Surgery on meningioma was debated from the point of view of the neurosurgeon and of the otologist. Endolymphatic sac tumors and malignant tumors of the external auditory canal were also treated, as well as chordomas, chondrosarcomas and petrous bone cholesteatomas. Finally, the fourth section focused on free-choice topics which were assigned to aknowledged experts. The aim of this work was attempting to report the state of the art of the lateral skull base surgery after 50 years of hard work and, above all, to raise questions on those issues which still need an answer, as to allow progress in knowledge through sharing of various experiences. At the end of the reading, if more doubts remain rather than certainties, the aim of this work will probably be achieved.

Disregarding the widely used division of skull base into anterior and lateral, since the skull base should be conceived as a single anatomic structure, it was to our convenience to group all those approaches that run from the antero-lateral, pure lateral and postero-lateral side of the skull base as “Surgery of the lateral skull base”. “50 years of endeavour” points to the great effort which has been made over the last decades, when more and more difficult surgeries were performed by reducing morbidity. The principle of lateral skull base surgery, “remove skull base bone to approach the base itself and the adjacent sites of the endo-esocranium”, was then combined with function preservation and with tailoring surgery to the pathology. The concept that histology dictates the extent of resection, balancing the intrinsic morbidity of each approach was the object of the first section of the present report. The main surgical approaches were described in the second section and were conceived not as a step-by-step description of technique, but as the highlighthening of the surgical principles. The third section was centered on open issues related to the tumor and its treatment. The topic of vestibular schwannoma was investigated with the current debate on observation, hearing preservation surgery, hearing rehabilitation, radiotherapy and the recent efforts to detect biological markers able to predict tumor growth. Jugular foramen paragangliomas were treated in the frame of radical or partial surgery, radiotherapy, partial “tailored” surgery and observation. Surgery on meningioma was debated from the point of view of the neurosurgeon and of the otologist. Endolymphatic sac tumors and malignant tumors of the external auditory canal were also treated, as well as chordomas, chondrosarcomas and petrous bone cholesteatomas. Finally, the fourth section focused on free-choice topics which were assigned to aknowledged experts. The aim of this work was attempting to report the state of the art of the lateral skull base surgery after 50 years of hard work and, above all, to raise questions on those issues which still need an answer, as to allow progress in knowledge through sharing of various experiences. At the end of the reading, if more doubts remain rather than certainties, the aim of this work will probably be achieved.