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H F Schuknecht

Publications and source records attributed to H F Schuknecht.

At least 19 recordsLinked to original sources
PubMed1992

Myths in neurotology.

For many diseases the etiology of disordered function is unknown and therapy is either symptomatic or empirical. The empirical approach to therapy is acceptable to many physicians, particularly if a treatment can be based on some attractive, although unproven, concept of pathogenesis. A hypothetical explanation of disordered function can become widely popular in spite of a serious lack of scientific support. When evidence emerges that refutes the logic of a concept of pathogenesis, then that concept becomes a myth. Human temporal bone studies have identified several myths in neurotology that deserve our attention. Among these myths are the following: (1) cochlear otosclerosis is a common cause for sensorineural hearing loss, (2) idiopathic sudden sensorineural hearing loss is a vascular disorder that should be treated as a medical emergency, (3) the conductive component of hearing loss in Paget's disease is caused by ossicular fixation and therefore should be surgically correctable, (4) vascular loops should be considered as a possible cause for otherwise unexplained otologic symptoms, (5) surgical manipulations on the endolymphatic sac are scientifically sound therapies for selected cases of Meniere's disease, and (6) perilymph fistulas are a common cause for audiovestibular symptoms that are not related to a stressful incident.

Ear Diseases↗
PubMed1991

Autosomal dominant sensorineural hearing loss. Pedigrees, audiologic findings, and temporal bone findings in two kindreds.

We report the clinical and otopathologic findings in three persons from two kindreds affected with adult-onset autosomal dominant progressive sensorineural hearing loss. The primary pathologic change is a deposit of acid polymucosaccharide ground substance in the cribrose areas; in the spiral ligament, limbus, and spinal lamina of the cochlea; and in the stroma of the maculae and cristae. These deposits obstruct the channels that accommodate the dendritic nerve fibers to the auditory and vestibular sense organs. The end result is strangulation and degeneration of dendrites followed by retrograde neuronal degeneration in association with varying degrees of atrophic change in the sense organs.

Adult↗
PubMed1991

Blockage of longitudinal flow in endolymphatic hydrops.

The external shunt operation on the endolymphatic sac is based on the concept that it will drain excess endolymph and thus arrest the progression of endolymphatic hydrops. We performed histological studies on 46 temporal bones from 13 cases of bilateral and 20 cases of unilateral Meniere's disease to evaluate the status of the pathways of longitudinal flow of endolymph to the sac. The endolymphatic ducts were blocked in 8 specimens (17%), the endolymphatic sinuses in 9 (19.5%), the utricular ducts in 12 (26%), the saccular ducts in 7 (15%), and the ductus reuniens in 27 (59%). These blockages arrested longitudinal flow from both the pars superior and inferior in 21 cases (46%), the pars superior only in 3 (6.5%), and the pars inferior only in 16 (35%). In the 6 ears with all pathways open, 2 were found to have fistulae between the saccules and the perilymphatic spaces, which theoretically results in internal shunting, thus alleviating the need for the external shunt procedure. In the aggregate, therefore, 42 (91%) of 46 ears showed either areas of blockage of longitudinal flow or internal shunts that would theoretically negate the value of external endolymphatic shunt procedures. These temporal bones, however, are from an autopsy population and the severity of pathological changes is probably greater than it would have been at an earlier age when external shunt surgery might have been a therapeutic consideration.

Adult↗
PubMed1991

The anterior inferior cerebellar artery in the internal auditory canal.

It has been proposed that compression of the auditory and vestibular nerve trunks by vascular loops might be the cause of otherwise unexplained hearing loss, tinnitus, and vertigo, as well as Meniere's disease. We studied the human temporal bone histological collection at the Massachusetts Eye and Ear Infirmary to determine whether audiovestibular symptoms could be correlated with the presence of the anterior inferior cerebellar artery within the internal auditory canal. Anterior inferior cerebellar artery loops were found within the internal auditory canals of 12.3% of 1327 temporal bones, about half the number found when preparations with intact brains are studied. This difference can be attributed to avulsion of the anterior inferior cerebellar artery during removal of the brain at autopsy. There were 5 cases of unexplained unilateral hearing loss with anterior inferior cerebellar artery loops: 3 in the opposite ear and 2 in both ears. There were 2 cases with unilateral unexplained tinnitus with anterior inferior cerebellar artery loops: 1 in the involved ear and 1 in the opposite ear. A case with bilateral tinnitus had an anterior inferior cerebellar artery loop in 1 ear. There were 29 cases of vertigo with no peripheral histopathological correlate or central nervous system disorder; anterior inferior cerebellar artery loops were found in the internal auditory canals of 7 (12.5%) of the 56 ears in this group, which is not significantly different from the 12.3% incidence recorded for the entire collection. In 23 cases of unilateral Meniere's disease, there were anterior inferior cerebellar artery loops in the hydropic ears in 3, the opposite ear in 1, and both ears in 1. We can find no correlation between unexplained hearing loss, tinnitus, vertigo, or Meniere's disease and the presence of the anterior inferior cerebellar artery in the internal auditory canal.

Adult↗
PubMed1990

In search of cochlear morphologic correlates for tinnitus.

A correlative study was made of the cochlear pathologic features existing in the temporal bones of 83 subjects with a clinical history of tinnitus and 33 without tinnitus. None of 24 types of pathologic change assessed by light microscope occurred in more than 40% of tinnitus cases; nor was the prevalence of any of these pathologic changes significantly greater in subjects with tinnitus compared with control subjects. For five types of morphologic alteration the prevalence was significantly greater among control subjects compared with tinnitus cases, but this is interpreted cautiously because of the challenge in retrospectively selecting an appropriate control group. Under the conditions of the study, that is, using light-microscopic techniques on tissues obtained post mortem, we could not identify a pathologic correlate for tinnitus.

Aged↗
PubMed1990

Delayed endolymphatic hydrops and its relationship to Meniére's disease.

Delayed endolymphatic hydrops (EH) can be characterized as having ipsilateral and contralateral types. They are similar in that both have early and late phases of otologic symptoms and that the early phase is a profound hearing loss in one ear. The late phases differ, however, in that the ipsilateral type develops the symptoms of EH (episodic vertigo) in the deaf ear and the contralateral type develops the symptoms of EH (fluctuating hearing loss and/or episodic vertigo) in the hearing ear. In more than half the cases of both types of delayed EH, the profound hearing losses in the early phase are simply discovered to be present in early childhood without a known time of onset. The temporal bones of two patients with contralateral delayed EH show pathologic changes in the deaf ears that are similar to those known to occur in mumps and measles labyrinthitis, whereas the pathologic changes in the hearing ears are similar to those known to occur in Meniere's disease. These observations support the proposition that Meniere's disease may occur as a delayed sequela of inner ear damage sustained during an attack of subclinical viral labyrinthitis occurring in childhood.

Adolescent↗
PubMed1990

Temporal bone findings in a case of bilateral Menière's disease treated by parenteral streptomycin and endolymphatic shunt.

A patient with bilateral Menière's disease who had progressive hearing loss and intractable vertigo was treated at ages 60 and 62 with parenteral streptomycin to ablate vestibular function, and at age 74 by a left endolymphatic shunt procedure. He was confined to a wheelchair because of ataxia from age 75 until the time of his death at age 81. Both temporal bones show congenitally hypoplastic endolymphatic sacs and severe endolymphatic hydrops consistent with Meniere's disease. There was atrophy of the striae vasculares and loss of cochlear neurons consistent with presbycusis. A loss of hair cells in the cristae and saccules was consistent with streptomycin ototoxicity. In the left ear the Silastic strip that was intended to function as an endolymphatic shunt into the mastoid lies encased in fibrous tissue and failed by 4.5 mm to reach the hypoplastic endolymphatic sac.

Ataxia↗
PubMed1990

In search of pathologic correlates for hearing loss and vertigo in Paget's disease. A clinical and histopathologic study of 26 temporal bones.

Mixed sensorineural and conductive hearing loss is a common clinical manifestation of Paget's disease of the temporal bone, and while there are numerous clinical and pathologic reports on the condition, none have identified a consistent pathologic explanation for the hearing loss. We performed histologic studies on 26 temporal bones exhibiting Paget's disease from 16 persons, of whom 7 had audiometric testing performed. Contrary to common opinion, the conductive hearing loss is not caused by ossicular fixation; in fact, no cause could be found in the seven ears with documented conductive hearing losses. While the sensorineural hearing losses were greater than normal for age, we could not identify cochlear disorders that could be attributed to Paget's disease. It is concluded that the hearing losses in Paget's disease are caused by changes in bone density, mass, and form that serve to dampen the finely tuned motion mechanics of the middle and inner ears.

Adult↗
PubMed1989

Is there a conductive type of presbycusis?

Many ears that manifest hearing losses caused by aging show combinations of atrophic change in the sensory cells, cochlear neurons, and stria vascularis. When it occurs in pure form, the loss of sensory cells produces an abruptly sloping high-tone threshold loss, the loss of cochlear neurons decreases the capability for speech discrimination, and the loss of strial tissue produces a flat threshold loss. There remains a fourth group of cases that have gradual sloping high-tone threshold losses for which a pathological correlate has not been identified. We performed a quantitative histologic study, using light microscopy on the temporal bones of such cases, and again could find no pathologic explanation. We believe that the findings of this study support the concept of an alteration in cochlear motion mechanics as the most probable cause for the gradually sloping high-tone hearing loss.

Age Factors↗
PubMed1989

Congenital aural atresia.

This report is based on 25 years' experience in the surgical management of 69 ears with congenital aural atresia. There were 7 ears with meatal atresia, 11 with partial atresia, 50 with total atresia, and 1 with hypopneumatic total atresia. Meatoplasty was performed in 7 ears, canaloplasty was performed in 22 ears, canaloplasties with strust in 8 ears, and mastoidectomy with stapediopexy was performed in 26 ears. Of the 62 ears that had partial or total atresia, five (8%) had hidden cholesteatomas that were destined to create future complications by expansion and erosion had they not been removed. In five of the 62 ears, temporary facial palsy resulted from exposing the facial nerve in the atresia plate, and in another five ears, attempts to improve hearing were abandoned intraoperatively because of surgically insurmountable anomalies. A reasonable criterion for success in an operation for bilateral atresia is that the need for a hearing aid is obviated; whereas, for unilateral atresia, a successful procedure should largely eliminate the disadvantages of unilateral hearing loss. These criteria seem to be satisfied if the threshold of hearing can be brought to a level of 20 dB or better. This criterion was met in 30% of the group that underwent canaloplasty and in 8% of the group that underwent mastoidectomy with stapediopexy.

Abnormalities, Multiple↗
PubMed1989

The pathology of peripheral vestibular disorders in the elderly.

We describe a clinical classification of vertigo commonly seen in the elderly and caused by peripheral vestibular disorders. The classification includes inducible transient vertigo and noninducible protracted vertigo. The peripheral vestibular disorder includes abnormalities of sensory, neural, and mechanical structures and is often asymmetric. Determination of the pathogenesis of these disorders is often speculative. Pathogenesis may include degenerative, infectious, neoplastic, and vascular insults to the vestibular labyrinth.

Aged↗
PubMed1988

The incidence of fibrosis in the vestibular ganglia in Menière's disease.

The vestibular ganglia in 11 temporal bones from subjects with known premortem unilateral Meniere's disease were studied for evidence of increased fibrosis. Tissue sections were treated with Gomori's trichrome stain and were examined independently by each of seven persons experienced in histological study. The averaged ratings for the amount of fibrous tissue in the vestibular ganglia showed no significant differences for ears with Meniere's disease, the opposite uninvolved ears, and the controls.

Aged↗
PubMed1988

Temporal bone pathology associated with intracranial abscess.

Histological studies were performed on the temporal bones of 17 persons who died of intracranial abscess as a complication of chronic otitis media and mastoiditis. In all cases the route of intracranial infection was via the dura mater rather than through the labyrinth. During the acute stage of intracranial abscess formation, the site of intracranial invasion showed a destructive inflammatory reaction characterized by the presence of granulations, resorption and sequestration of bone, invasive cholesteatoma, collections of purulent exudate, and necrosis of dura mater. At this stage any attempt at definitive removal of diseased tissue would necessarily result in a larger dural defect at a time when local disease and systemic illness present unsuitable conditions for reparative procedures. For this reason it would seem prudent to limit early otologic surgery to ensuring adequate drainage (e.g., postauricular open-wound drainage) and to perform corrective surgery (e.g., tympanomastoidectomy with repair of the dural defect) after the intracranial abscess has been brought under control.

Adolescent↗
PubMed1988

Atrophy of the stria vascularis as a cause of sensorineural hearing loss.

Correlations were made between pure-tone thresholds and computer-aided cross-sectional measurements of the stria vascularis on histological sections of postmortem cochleas from 24 subjects who had reliable audiometric records. The criterion for selection was strial atrophy as the predominant pathological change in 17 experimental ears and normal hearing for seven control ears. Losses in the summed cross-sectional areas of stria vascularis showed a direct correlation with hearing loss. The cause for the strial atrophy is presumed to be a genetically determined predisposition for early cellular decay. The mechanism by which strial atrophy causes hearing loss is speculative.

Aged↗