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Otolaryngology--head and Neck Surgery :... Dec 1997Hearing loss during removal of acoustic neuroma (AN) may be due to labyrinthine and/or neural and/or vascular damage. Surgical maneuvers relating to perioperative and...
Hearing loss during removal of acoustic neuroma (AN) may be due to labyrinthine and/or neural and/or vascular damage. Surgical maneuvers relating to perioperative and postoperative hearing may give rise to mechanisms of auditory impairment. Recording action potentials from the intracranial portion of the cochlear nerve (CN) has proven particularly useful for identifying the mechanisms of iatrogenic auditory injury. In this paper intraoperative and postoperative auditory impairments are investigated in relation to surgical steps in a group of 47 subjects with AN (size ranging from 5 to 25 mm) undergoing removal by a retrosigmoid-transmeatal approach. Drilling of the internal auditory canal (IAC), removal of the AN from the IAC fundus, coagulation close to the CN, lateral to medial tumor traction, separation of the CN from the facial nerve, and stretching of the CN have proven to be the most critical surgical steps in hearing preservation. On the other hand, maneuvers such as intracapsular tumor removal, vestibular neurectomy, suction close to the AN, and closure of the IAC defect did not correlate with changes in auditory potentials. Predisposing factors to postoperative hearing deterioration were IAC enlargement greater than 3 mm, IAC tumor size greater than 7 mm, extracanalar tumor size greater than 20 mm, labyrinth medial to the IAC fundus, severe involvement of the CN in the IAC, preoperative abnormal auditory brainstem responses, and normal vestibular reflectivity. Age and preoperative hearing did not prove to be statistically related to postoperative hearing. The variations in morphology and latency of CNAPs are discussed in relation to the mechanisms of iatrogenic injury.
Topics: Adolescent; Adult; Aged; Blood Vessels; Cochlear Nerve; Ear, Inner; Evoked Potentials, Auditory; Female; Hearing Disorders; Humans; Intraoperative Complications; Male; Middle Aged; Neuroma, Acoustic; Postoperative Complications; Reaction Time
PubMed: 9419085
DOI: 10.1016/S0194-59989770039-1 -
Science (New York, N.Y.) Mar 1970Fourier analysis of discharge patterns in response to sinusoidal acoustic stimulation provides a consistent and repeatable measure of response phase and amplitude. The...
Fourier analysis of discharge patterns in response to sinusoidal acoustic stimulation provides a consistent and repeatable measure of response phase and amplitude. The variation of the fundamental and harmonic components of the patterns as stimulus parameters are changed is strikingly similar to that of cochlear microphonics. The results are significantly different for single fibers with different characteristic frequencies; the variations parallel those of microphonics recorded from different cochlear turns.
Topics: Acoustics; Animals; Cats; Cochlea; Cochlear Nerve; Evoked Potentials; Nerve Fibers, Myelinated
PubMed: 5415172
DOI: 10.1126/science.167.3925.1614 -
Biofizika 1960
Topics: Acoustics; Animals; Cochlear Nerve; Ranidae
PubMed: 13828425
DOI: No ID Found -
The Journal of Biophysical and... Apr 1961The eighth cranial nerve ganglion consists of bipolar nerve cell bodies each occupying part of an internodal segment. The perikaryal sheaths range from a single layer of...
The eighth cranial nerve ganglion consists of bipolar nerve cell bodies each occupying part of an internodal segment. The perikaryal sheaths range from a single layer of Schwann cell cytoplasm on the smallest cells to typical thick compact myelin on the largest. On most perikarya, the sheath displays an intermediate form, consisting of multiple layers of Schwann cell cytoplasm (loose myelin), or of loose and compact myelin continuous with each other. Internodes beyond the one containing the cell body bear only compact myelin. In loose myelin the thickness of each layer of Schwann cell cytoplasm is about 100 A. It may be much greater ( approximately 3000 A) particularly in the outermost layers of the sheath, or the cytoplasm may thin and even disappear with formation of a major dense line. The cytoplasmic layers are separated from each other by a light zone, 40 to 200 A wide, which in its broader portions may contain an intermediate line. Desmosomes sometimes occur between lamellae. In addition to the usual organelles, the perikaryal cytoplasm contains granular and membranous inclusions. Large cells covered by compact myelin have a consistently higher concentration of neurofilaments, and some of the largest cells, in addition, show a reduced concentration of ribosomes. The functional significance and possible origins of perikaryal myelin sheaths are discussed.
Topics: Animals; Axons; Cell Body; Cochlear Nerve; Cytoplasm; Cytoplasmic Granules; Fishes; Ganglia; Goldfish; Histological Techniques; Myelin Sheath; Neurons
PubMed: 13743432
DOI: 10.1083/jcb.9.4.853 -
Archives of Oto-rhino-laryngology 1988The topographical and cytological features of the pigmented mouse (CBA/CBA) cochlear nerve were analyzed. The cochlear nerve is very short and is approximately 0.2-0.3...
The topographical and cytological features of the pigmented mouse (CBA/CBA) cochlear nerve were analyzed. The cochlear nerve is very short and is approximately 0.2-0.3 mm in its length. The entire cochlear nerve and a portion of the ventral cochlear nucleus are located within the internal acoustic meatus, and are closely surrounded by bone. Approximately 10,000 nerve fibers are present, of which only about 3% are unmyelinated. The distribution of the axon diameters in the myelinated nerves is close to unimodal.
Topics: Animals; Cochlear Nerve; Mice; Mice, Inbred CBA; Nerve Fibers, Myelinated; Vestibular Nerve
PubMed: 3178564
DOI: 10.1007/BF00464018 -
Archives of Otolaryngology (Chicago,... Dec 1964
Topics: Cerebral Arteries; Cochlear Nerve; Ear, Inner; Neoplasms; Neurilemmoma; Neuroma, Acoustic; Neurosurgery; Prognosis; Temporal Bone; Vestibulocochlear Nerve
PubMed: 14205475
DOI: No ID Found -
Archives of Otolaryngology (Chicago,... Dec 1964
Topics: Audiometry; Cochlear Nerve; Deafness; Diagnosis, Differential; Hearing Tests; Humans; Neoplasms; Neurilemmoma; Neuroma, Acoustic; Neurosurgery; Preoperative Care
PubMed: 14205465
DOI: 10.1001/archotol.1964.00750040683006 -
Archives of Otolaryngology (Chicago,... Oct 1964
Topics: Cochlea; Cochlear Nerve; Electric Stimulation; Hearing; Hearing Tests; Humans
PubMed: 14198698
DOI: No ID Found -
Jibi Inkoka Otolaryngology Apr 1965
Topics: Cochlear Nerve; Deafness; Hearing Loss, Sudden; Humans; Labyrinth Diseases; Neuritis; Vestibulocochlear Nerve
PubMed: 14299162
DOI: No ID Found -
Gaceta Medica de Mexico Nov 1964
Topics: Cochlear Nerve; Deafness; Humans; Peripheral Nervous System Diseases; Syndrome; Vestibule, Labyrinth
PubMed: 14225084
DOI: No ID Found