Biomaterial Database

Neurotopographic considerations in the microsurgical treatment of small acoustic neurinomas. 1998

W T Koos, and J D Day, and C Matula, and D I Levy

Department of Neurosurgery, University of Vienna, Austria.

OBJECTIVE The authors studied the relationships between tumor size, location, and topographic position relative to the intact facial nerve bundles in acoustic neurinomas to determine the influence of these factors on hearing preservation postoperatively. Consistent topographic relationships were found. METHODS Four hundred fifty-two patients with acoustic neurinoma treated via a retrosigmoid approach were analyzed with respect to hearing preservation and facial nerve function. One hundred fifteen tumors were identified as small and were categorized as Grades I and II. Patients with Grade I tumors, that is, purely intracanalicular lesions, all had good hearing preoperatively, defined by a less than 50-dB pure tone average and 50% speech discrimination score. All 14 Grade I tumors were removed, resulting in preservation of the patient's hearing by these criteria. There were no particular topographic anatomical relationships associated with these tumors that affected hearing preservation. Grade II tumors, defined as those protruding into the cerebellopontine angle without contacting the brainstem, were found in 101 patients and were divided by size into two grades: IIA (< 1 cm) and IIB (1-1.8 cm). In 90 patients with Grade IIA tumors, 72 (89%) of 81 who had preserved hearing preoperatively maintained it postoperatively, and in the 11 patients with Grade IIB tumors, six of whom had good hearing preoperatively, four (67%) had preserved hearing postoperatively. Six morphological types were identified based on their neurotopographic relationships to the elements of the vestibulocochlear nerve. CONCLUSIONS Hearing preservation postsurgery by tumor type was as follows: 1A, 92%; 1B, 88%; 1C, 100%; 2A, 83%; 2B, 92%; and 3, 57%. Combined, this represents a hearing preservation rate of 87% after surgical treatment of Grade II acoustic neurinomas. Full nerve function was maintained in 88% of patients with anatomically preserved facial nerves in both Grade I and II tumors. The remaining 12% of patients retained partial function of the facial nerve. Two patients in the series lost anatomical integrity of the nerve due to surgery.

UI	MeSH Term	Description	Entries
D008416	Mastoid	The posterior part of the temporal bone. It is a projection of the petrous bone.	Mastoid Foramen,Mastoid Bone,Mastoid Process,Bone, Mastoid,Foramen, Mastoid,Mastoid Bones,Mastoid Processes,Mastoids,Process, Mastoid
D008866	Microsurgery	The performance of surgical procedures with the aid of a microscope.
D009464	Neuroma, Acoustic	A benign SCHWANNOMA of the eighth cranial nerve (VESTIBULOCOCHLEAR NERVE), mostly arising from the vestibular branch (VESTIBULAR NERVE) during the fifth or sixth decade of life. Clinical manifestations include HEARING LOSS; HEADACHE; VERTIGO; TINNITUS; and FACIAL PAIN. Bilateral acoustic neuromas are associated with NEUROFIBROMATOSIS 2. (From Adams et al., Principles of Neurology, 6th ed, p673)	Acoustic Neuroma,Melanocytic Vestibular Schwannoma,Schwannoma, Acoustic,Schwannoma, Vestibular,Acoustic Neuroma, Cerebellopontine Angle,Acoustic Tumor,Angle Tumor,Cerebellopontine Angle Acoustic Neuroma,Cerebellopontine Angle Tumor,Neurilemmoma, Acoustic,Neurilemoma, Acoustic,Neurinoma of the Acoustic Nerve,Neurinoma, Acoustic,Neuroma, Acoustic, Unilateral,Vestibular Schwannoma,Acoustic Neurilemmoma,Acoustic Neurilemmomas,Acoustic Neurilemoma,Acoustic Neurilemomas,Acoustic Neurinoma,Acoustic Neurinomas,Acoustic Neuromas,Acoustic Schwannoma,Acoustic Schwannomas,Acoustic Tumors,Angle Tumor, Cerebellopontine,Angle Tumors,Angle Tumors, Cerebellopontine,Cerebellopontine Angle Tumors,Melanocytic Vestibular Schwannomas,Neurilemmomas, Acoustic,Neurilemomas, Acoustic,Neurinomas, Acoustic,Neuromas, Acoustic,Schwannoma, Melanocytic Vestibular,Schwannomas, Acoustic,Schwannomas, Melanocytic Vestibular,Schwannomas, Vestibular,Tumor, Acoustic,Tumor, Angle,Tumor, Cerebellopontine Angle,Tumors, Acoustic,Tumors, Angle,Tumors, Cerebellopontine Angle,Vestibular Schwannoma, Melanocytic,Vestibular Schwannomas,Vestibular Schwannomas, Melanocytic
D010579	Petrous Bone	The dense rock-like part of temporal bone that contains the INNER EAR. Petrous bone is located at the base of the skull. Sometimes it is combined with the MASTOID PROCESS and called petromastoid part of temporal bone.	Petrous Apex,Petrous Pyramid,Bone, Petrous,Petrous Bones
D001933	Brain Stem	The part of the brain that connects the CEREBRAL HEMISPHERES with the SPINAL CORD. It consists of the MESENCEPHALON; PONS; and MEDULLA OBLONGATA.	Brainstem,Truncus Cerebri,Brain Stems,Brainstems,Cerebri, Truncus,Cerebrus, Truncus,Truncus Cerebrus
D002530	Cerebellopontine Angle	Junction between the cerebellum and the pons.	Cerebellopontile Angle,Angle, Cerebellopontile,Angle, Cerebellopontine,Angles, Cerebellopontile,Angles, Cerebellopontine,Cerebellopontile Angles,Cerebellopontine Angles
D003056	Cochlear Nerve	The cochlear part of the 8th cranial nerve (VESTIBULOCOCHLEAR NERVE). The cochlear nerve fibers originate from neurons of the SPIRAL GANGLION and project peripherally to cochlear hair cells and centrally to the cochlear nuclei (COCHLEAR NUCLEUS) of the BRAIN STEM. They mediate the sense of hearing.	Acoustic Nerve,Auditory Nerve,Acoustic Nerves,Auditory Nerves,Cochlear Nerves,Nerve, Acoustic,Nerve, Auditory,Nerve, Cochlear,Nerves, Acoustic,Nerves, Auditory,Nerves, Cochlear
D005154	Facial Nerve	The 7th cranial nerve. The facial nerve has two parts, the larger motor root which may be called the facial nerve proper, and the smaller intermediate or sensory root. Together they provide efferent innervation to the muscles of facial expression and to the lacrimal and SALIVARY GLANDS, and convey afferent information for TASTE from the anterior two-thirds of the TONGUE and for TOUCH from the EXTERNAL EAR.	Cranial Nerve VII,Marginal Mandibular Branch,Marginal Mandibular Nerve,Seventh Cranial Nerve,Nerve VII,Nerve of Wrisberg,Nervus Facialis,Nervus Intermedius,Nervus Intermedius of Wrisberg,Cranial Nerve VIIs,Cranial Nerve, Seventh,Facial Nerves,Mandibular Nerve, Marginal,Mandibular Nerves, Marginal,Marginal Mandibular Nerves,Nerve VIIs,Nerve, Facial,Nerve, Marginal Mandibular,Nerve, Seventh Cranial,Nerves, Marginal Mandibular,Nervus Faciali,Seventh Cranial Nerves,Wrisberg Nerve,Wrisberg Nervus Intermedius
D005500	Follow-Up Studies	Studies in which individuals or populations are followed to assess the outcome of exposures, procedures, or effects of a characteristic, e.g., occurrence of disease.	Followup Studies,Follow Up Studies,Follow-Up Study,Followup Study,Studies, Follow-Up,Studies, Followup,Study, Follow-Up,Study, Followup
D006309	Hearing	The ability or act of sensing and transducing ACOUSTIC STIMULATION to the CENTRAL NERVOUS SYSTEM. It is also called audition.	Audition