Hearing loss after neurosurgery. The influence of low cerebrospinal fluid pressure

Chronic craniomandibular pain after craniotomy: A long-term clinical study

OBJECTIVE

Chronic craniomandibular/cervical pain and temporomandibular disorders have not been studied in patients who had a craniotomy several years previously. The aim of the current clinical work was to address these issues.

METHODS

A total group of 150 ambulant patients who had a previous craniotomy was subclassified according to whether or not the temporalis muscle was manipulated.

RESULTS

The average incidence of multiple subsite regional head and neck pain was 69.3% a number of years after a craniotomy. Evidence of internal derangement of the temporomandibular joint was significantly higher in the group that required manipulation of the temporalis muscle during the procedure.

CONCLUSION

The pattern of chronic craniomandibular/cervical pain experienced years after a craniotomy supports the brain neuromatrix theory of pain.

MRI With Intratympanic Gadolinium: Comparison Between Otoneurological and Radiological Investigation in Menière's Disease

Objectives/hypothesis: To compare findings obtained using both magnetic resonance imaging plus intratympanic gadolinium and audiovestibular testing for Menière's disease.

Study design: Retrospective cohort study.

Methods: Patients with definite unilateral Menière's disease (n = 35) diagnosed according to 2015 Barany Criteria were included. Three-dimensional real inversion recovery (3D-real-IR) MRI was executed 24 h after intratympanic gadolinium injection to assess the presence and degree of endolymphatic hydrops. Pure tone audiometry, bithermal caloric test, head impulse test, ocular, and cervical VEMPs using air-conducted sound were performed to evaluate the level of hearing and vestibular loss. The results were compared to verify precision of the method in providing correct diagnoses.

Results: Different degrees of endolymphatic hydrops were observed in the MRI of the cochlea and vestibule in the affected ears of Menière's disease patients, even though it was impossible to radiologically distinguish the two otolithic structures separately. The correlation between the degree of linked alterations between instrumental and MRI testing was statistically significant. In particular, an 83% correspondence with audiometry, a 63% correspondence for cVEMPs and 60% correspondence for cVEMPs were seen. While for HIT the accordance was 70 and 80% for caloric bithermal test.

Conclusions: MRI using intratympanic gadolinium as a contrast medium has proved to be a reliable and harmless method, even though there is an objective difficulty in disclosing macular structures. The study revealed that there is no complete agreement between instrumental values and MRI due to the definition of the image and fluctuation of symptoms. The present work highlights the greater (but not absolute) sensitivity of otoneurological tests while MRI, although not yet essential for diagnosis, is certainly important for understanding the disease and its pathogenic mechanisms.

Sensorineural Hearing Loss in the Nonimplanted Ear Following Cochlear Implantation in a Patient With Bilateral Enlarged Vestibular Aqueducts

OBJECTIVE

To document the case of a patient with bilateral enlarged vestibular aqueducts who experienced sensorineural hearing loss in the nonimplanted ear following unilateral cochlear implantation complicated by perilymph gusher requiring lumbar drain insertion and to highlight the need to counsel regarding the risk of potential hearing loss to the contralateral ear when preparing for cochlear implants in the setting of inner ear malformations.

PATIENTS

One patient with bilateral enlarged vestibular aqueducts in a tertiary referral center.

INTERVENTION(S)

Cochlear implantation complicated by perilymph gusher requiring lumbar drain insertion.

MAIN OUTCOME MEASURE(S)

Bone conduction hearing thresholds, word recognition scores.

RESULTS

The patient underwent unilateral cochlear implantation, which was complicated by a perilymphatic gusher and necessitated placement of an intraoperative lumbar drain. On postoperative day 1, the patient reported hearing loss in the opposite ear. The word recognition score in the contralateral ear dropped from 24% at preimplantation to 8% at 2-weeks postimplantation, and did not improve at 6 months postimplantation. Moreover, the bone conduction threshold at 1 kHz worsened from 20 dB preoperatively to no response at 75 dB (the limit of the testing equipment) at 2-weeks postoperatively and only partially improved to 40 dB at 6 months postimplantation.

CONCLUSION

As patients with inner ear malformations potentially have direct high-pressure anatomical connections between the perilymphatic spaces and the cerebrospinal fluid, they are at risk of hearing loss in the nonimplanted ear during cochlear implantation. This case highlights the need for potential additional patient counseling regarding this risk in the nonimplanted ear.

Recommendations for ototoxicity surveillance for childhood, adolescent, and young adult cancer survivors: a report from the International Late Effects of Childhood Cancer Guideline Harmonization Group in collaboration with the PanCare Consortium

Childhood, adolescent, and young adult (CAYA) cancer survivors treated with platinum-based drugs, head or brain radiotherapy, or both have an increased risk of ototoxicity (hearing loss, tinnitus, or both). To ensure optimal care and reduce consequent problems-such as speech and language, social-emotional development, and learning difficulties-for these CAYA cancer survivors, clinical practice guidelines for monitoring ototoxicity are essential. The implementation of surveillance across clinical settings is hindered by differences in definitions of hearing loss, recommendations for surveillance modalities, and remediation. To address these deficiencies, the International Guideline Harmonization Group organised an international multidisciplinary panel, including 32 experts from ten countries, to evaluate the quality of evidence for ototoxicity following platinum-based chemotherapy and head or brain radiotherapy, and formulate and harmonise ototoxicity surveillance recommendations for CAYA cancer survivors.

Asymmetric hearing loss and chronic dizziness in a patient with idiopathic normal pressure hydrocephalus

We report a case of a 54-year old female patient, complaining for chronic dizziness, hearing loss, tension headaches without aura, postural instability and gait dysfunction. The patient referred having these symptoms from 1992, but the last few months she experienced a noticeable aggravation of the symptoms. A magnetic resonance imaging test revealed a triventricular hydrocephalus, not associated with signs of intracranial hypertension decompensation. The ENT-Audiology evaluation revealed a bilateral sensorineural hearing loss with a conductive component, video-nystagmography resulted in an areflexia of the right ear and a reduced vestibular activity for the left ear. Auditory brainstem response test was also carried out and showed pathologic findings for the latencies of the waves I-III, III-V and I-V bilaterally but more significant in the right ear. On January 2016 the patient had endoscopic third ventriculostomy. On the follow up the patient referred an important subjective improvement regarding instability and gait dysfunction. In this paper we study the correlation between hydrocephalus, hearing loss and vestibular dysfunction.

Resolution of bilateral sensorineural hearing loss following ventriculoperitoneal shunt and literature review

OBJECTIVE

The purpose of this study is to highlight the relationship between obstructive hydrocephalus, changes in intracranial pressure, and sensorineural hearing loss.

METHODS

A case of a 10-month old infant with sensorineural hearing loss secondary to obstructive hydrocephalus is reported. A literature review, with a focus on sensorineural hearing loss in the setting of changes in intracranial pressure, was performed.

RESULTS

The authors report the case of a 10-month old infant with metopic and bicoronal craniosynostosis who presented with bilateral moderately severe sensorineural hearing loss after failing newborn hearing screening. Imaging subsequently demonstrated obstructive hydrocephalus, which was treated with the insertion of a VP shunt. The patient had immediate improvement of her hearing post-operatively, with repeat hearing tests showed resolution of her hearing loss.

CONCLUSION

Sensorineural hearing loss is a rare complication of hydrocephalus, but changes in intracranial pressure should be considered in the differential diagnosis. We put forth a flow diagram illustrating the hypothesized relationship between intracranial pressures, alterations in the levels of cochlear fluid, and hearing.

Spontaneous Intracranial Hypotension: A Rare Cause of Labyrinthine Hydrops

Spontaneous intracranial hypotension should be considered as a possible cause of cochlear hydrops. We report a case of unilateral hearing loss attributed to spontaneous intracranial hypotension on the basis of characteristic abnormalities seen on magnetic resonance imaging. The diagnostic gold standards for intracranial hypotension are lumbar measurement of cerebrospinal fluid pressure and magnetic resonance imaging. The usual treatment is an autologous blood injection into the peridural spaces. The mechanism of hearing loss is thought to involve secondary perilymph depression due to a patent cochlear aqueduct. This perilymph depression would induce a compensatory expansion of the endolymphatic compartment, with a subsequent decrease in basilar or Reissner's membrane compliance. Endolymphatic hydrops can occur in the course of intracranial hypotension, and not only because of abnormal endolymph production or resorption. Hydrops can thus be classified into 1) syndromes of endolymphatic origin and 2) syndromes of perilymphatic origin, in which loss of perilymph induces compensatory expansion of the endolymphatic space.

An allograft mouse model for the study of hearing loss secondary to vestibular schwannoma growth

Vestibular schwannoma is a benign neoplasm arising from the Schwann cell sheath of the auditory-vestibular nerve. It most commonly affects both sides in the genetic condition Neurofibromatosis type 2, causing progressive high frequency sensorineural hearing loss. Here, we describe a microsurgical technique and stereotactic coordinates for schwannoma cell grafting in the vestibular nerve region that recapitulates local tumor growth in the cerebellopontine angle and inner auditory canal with resulting hearing loss. Tumor growth was monitored by bioluminescence and MRI in vivo imaging, and hearing assessed by auditory brainstem responses. These techniques, by potentially enabling orthotopic grafting of a variety of cell lines will allow studies on the pathogenesis of tumor-related hearing loss and preclinical drug evaluation, including hearing endpoints, for NF2-related and sporadic schwannomas.

Hearing Loss in Patients Who Received Cranial Radiation Therapy for Childhood Cancer

PURPOSE

Patients treated with cranial radiation therapy (RT) are at risk for sensorineural hearing loss (SNHL). Although SNHL is often characterized as a delayed consequence of anticancer therapy, longitudinal reports of SNHL in childhood cancer survivors treated with contemporary RT are limited. We report the incidence, onset, severity, and long-term trajectory of SNHL among children receiving RT. Potential risk factors for SNHL were also identified.

PATIENTS AND METHODS

Serial audiologic testing was conducted on 235 pediatric patients who were treated with conformal or intensity-modulated RT as part of an institutional phase II trial for localized primary brain tumors, including craniopharyngioma, ependymoma, and juvenile pilocytic astrocytoma. All but one patient had measurable cochlear radiation dose (CRD) greater than 0 Gy. The median follow-up from RT initiation to latest audiogram was 9 years with a median of 11 post-RT audiograms per patient. Audiograms were classified by the Chang Ototoxicity Grading Scale. Progression was defined by an increase in Chang grade from SNHL onset to the most recent evaluation.

RESULTS

At last evaluation, SNHL was prevalent in 14% of patients: 2.1% had mild and 11.9% had significant SNHL requiring hearing aids. Median time from RT to SNHL onset was 3.6 years (range, 0.4 to 13.2 years). Among 29 patients with follow-up evaluations after SNHL onset, 65.5% experienced continued decline in hearing sensitivity in either ear and 34.5% had no change. Younger age at RT initiation (hazard ratio [HR], 2.32; 95% CI, 1.21 to 4.46), higher CRD (HR, 1.07; 95% CI, 1.03 to 1.11), and cerebrospinal fluid shunting (HR, 2.02; 95% CI, 1.07 to 3.78) were associated with SNHL.

CONCLUSION

SNHL is a late effect of RT that likely worsens over time. Long-term audiologic follow-up for a minimum of 10 years post-RT is recommended.

Sudden sensorineural hearing loss after non-otologic surgery

Sudden sensorineural hearing loss following non-otologic surgery is a rare event described in the medical literature. Cardiopulmonary bypass surgery is most commonly associated with this type of hearing loss. Our case report and review of the literature describe two cases with postoperative hearing loss - neither of which are cardiac surgeries - making them exceedingly rare in the medical literature. Regardless of the rarity of this unfortunate event, the possibility for permanent hearing loss is a potentially devastating unanticipated complication and one that all surgeons should be aware.

A new possible mechanism of hearing loss after microvascular decompression for hemifacial spasm

OBJECTIVE

Hearing loss is a well-known complication that may occur during microvascular decompression (MVD) for hemifacial spasm (HFS). Cause and risk factors are highly variable. We present cases of hearing loss induced by saline overinfusion after MVD.

STUDY DESIGN

Retrospective review in a tertiary referral center.

INTERVENTION

Three hundred thirty-one patients with HFS underwent MVD from March 2009 to October 2010.

MAIN OUTCOME MEASURES

Brain stem auditory evoked potential (BAEP) was monitored during the surgery. Before completion of the dural closure, the surgical field was routinely filled with warm saline to avoid postoperative pneumocephalus and epidural hematoma.

RESULTS

Seven patients experienced a change in wave V amplitude and latency after the dural closure. In 2 patients, the amplitudes decreased by less than 50%, and latencies were delayed by less than 1.0 ms, ipsilaterally in 1 patient and contralaterally in the other. In 1 patient, decreased amplitude and delayed latency appeared bilaterally with more severity on the operated side, accompanied by delayed ipsilateral permanent hearing loss. In 4 of the 7 patients, an ipsilateral response of BAEP was completely absent. Of these 4 patients, 2 experienced permanent hearing loss, and another 2 patients who underwent dural reopening and saline drainage had restoration of their normal hearing.

CONCLUSION

Intradural compression due to overinfusion of saline may lead to postoperative hearing loss, although the incidence is low, and immediate decompression by drainage may be required.

Hearing loss following ventriculoperitoneal shunt in communicating hydrocephalus patients: a pilot study

OBJECTIVES/HYPOTHESIS

Hearing loss can be associated with a decrease in cerebrospinal fluid (CSF) pressure because changes in CSF pressure induce changes in perilymph pressure. Hearing loss after neurosurgical procedures have been reported, but clinical information on hearing loss after the placement of ventriculoperitoneal (VP) shunts, the most commonly used CSF shunt for hydrocephalus patients, is limited. This study is aimed to show the relationship between VP shunt and hearing loss.

STUDY DESIGN

Prospective study.

METHODS

Pure tone threshold and electrocochleography were preoperatively performed in nine patients (18 ears) undergoing elective VP shunt placement. Five-day and 1-month post-shunt placement hearing thresholds were compared with baseline data. A correlation analysis was conducted between the threshold and summating potential/action potential (SP/AP) ratio changes at 5 days and 1 month after shunt placement. Cochlear aqueduct dimensions measured by high-resolution CT were compared between ears with and without hearing loss.

RESULTS

About 40% of subject ears showed hearing loss with a threshold elevation of at least 15 dB in one or more frequencies. After VP shunt placement, the mean threshold of all ears showed a significant increase in most frequencies and the pure tone average. The change in the SP/AP ratios was significantly correlated with the change in the pure tone average at both 5 days and 1 month after shunt placement. Cochlear aqueduct dimensions were not correlated with hearing loss occurrence.

CONCLUSIONS

Hearing thresholds may increase following VP shunt placement, possibly due to secondary endolymphatic hydrops.

Cerebrospinal fluid shunting and hearing loss in patients treated for medulloblastoma

OBJECT

Cerebrospinal fluid shunting has previously been associated with hearing loss. Although the mechanism for this is unclear, it is thought that changes in CSF pressure can affect cochlear physiology via endolymph expansion in the setting of a patent cochlear aqueduct. Patients undergoing radiation and cisplatin chemotherapy are at risk for hearing loss. The authors hypothesized that the incidence and severity of hearing loss in patients undergoing radiation and chemotherapy for medulloblastoma would be greater in those with shunts than in those without shunts.

METHODS

Baseline and longitudinal audiology data were collected in 33 patients with medulloblastoma who were receiving radiation and cisplatin chemotherapy. Additional data included age, sex, details of shunt placement and revision, and details of chemotherapy and radiation. Hearing sensitivity and peripheral auditory function measures included pure tone audiometry, immittance audiometry, and distortion product evoked otoacoustic emissions. Ototoxicity was determined according to the American Speech-Language-Hearing Association criteria. Severity of hearing loss was determined using the Brock hearing loss grades. Incidence of hearing loss and association with shunting was determined.

RESULTS

Thirteen (39.4%) of the 33 patients evaluated had undergone shunt placement. Hearing loss occurred in 14 (70%) of 20 patients without shunts and in 13 (100%) of 13 patients with shunts. The difference between the rates of hearing loss in patients with shunts versus those without the devices was highly significant (p = 0.0008). The odds ratio for hearing loss in patients with a CSF shunt compared with those without a shunt was 23.49 (95% CI 4.21-131.15). Age, side of shunt, evidence of dissemination, diameter of cochlear aqueduct, and treatment protocol did not have a significant effect on shunt-related ototoxicity.

CONCLUSIONS

This study suggests an independent association between CSF shunting and hearing loss in children undergoing treatment for medulloblastoma, laying the foundation for a prospective study evaluating hearing loss in children with shunts who are not treated with ototoxic therapy.

Cochlear implantation for total deafness after ipsilateral ventriculoperitoneal shunt surgery: technical report

BACKGROUND

Cochlear implantation (CI) becomes more challenging when a programmable ventriculoperitoneal (VP) shunt is present on the same side of the head. We report a successful ipsilateral CI in a patient who suffered bilateral hearing loss after shunt surgery.

METHOD

We describe the CI case of a 49-year-old woman with an implanted VP shunt device, and perform a retrospective review of the clinical, audiological, and radiological features, surgical techniques, and postoperative functional outcomes.

FINDINGS

During CI, the magnet in the core of internal antenna of the CI device was positioned approximately 8 cm from the shunt valve so that it would not be affected by the magnetic field of the programmable valve. Although the CI antenna tip and shunt catheter overlapped, we were very careful not to pull the shunt catheter out of position while the musculoperiosteal flap was elevated.

CONCLUSIONS

The present result suggests that ipsilateral CI is an option for deaf adult patients who have a programmable shunt.

Resolution of hydrocephalus-associated sensorineural hearing loss after insertion of ventriculoperitoneal shunt

The authors present a pediatric patient with severe hearing loss due to communicating hydrocephalus. This is the first clearly documented case of de novo sensorineural deafness caused by hydrocephalus, with subsequent improvement in hearing after shunt insertion. The patient initially presented with otitis media and was found to have hearing loss. After reporting ongoing headaches, he received a diagnosis of communicating hydrocephalus, which was treated with the insertion of a ventriculoperitoneal shunt. Formal hearing tests showed dramatic improvement postsurgery; his hearing was normal at 2 months. At 3 years postsurgery the patient's hearing remains within normal limits. Hearing loss is a rare complication of hydrocephalus. Based on this case, the authors suggest that the diagnosis of hydrocephalus be considered as a cause of unexplained hearing loss, and conversely, that patients with hydrocephalus might benefit from hearing assessment.

Hearing Loss and Cerebrospinal Fluid Pressure: Case Report and Review of the Literature

A decrease in cerebrospinal fluid pressure may result in an endolymphatic hydrops through a patent cochlear aqueduct or through the fundus of the internal auditory canal. This hydrops typically leads to low-frequency sensorineural hearing loss. We describe the case of a man who presented with a subjective and objective hearing loss in addition to a headache 4 days after he had undergone a dural puncture. We treated him with a standard epidural blood patch. Immediately after treatment, his hearing improved and his headache resolved.

Sensorineural hearing changes after myelogram

Dire consequences can occur after any medical or surgical procedure. Certain procedures may even cause sensorineural hearing loss (SNHL). Previous studies have demonstrated that certain surgical and medical procedures may result in hearing losses of varying degrees. Although hearing loss is a well-known phenomenon, little consistent information exists about hearing loss after medical or surgical procedures. This one-tailed, directional study compared the effect of myelogram procedures on hearing in selected outpatients. A pre/posttest design was used to measure audiograms in 27 myelogram subjects. Pre- and postprocedure hearing tests were measured by audiometry and compared for differences. Results did not support previous studies that low-frequency hearing loss can occur within 24 hours after myelogram procedure. Clinically relevant information was found in one subject 53 hours post myelogram.

Unilateral sensorineural hearing loss after spine surgery: case report and review of the literature

BACKGROUND

Sudden sensorineural hearing loss is infrequent, with an estimated incidence of 5 to 20 cases yearly per 100,000 people. Although multiple etiologies have been identified, infection and idiopathic SNHL are most common. Sudden sensorineural hearing loss after nonotologic noncardiac surgery is highly unusual, particularly after spinal surgery.

CASE DESCRIPTION

We report a case of unilateral sudden SNHL after lumbar spinal fusion with review of the literature. Potential etiologies, treatment, and prognosis are summarized.

CONCLUSION

Multiple etiologies have been proposed for SNHL after nonotologic noncardiac surgery. Excessive positive upper airway pressure during induction of anesthesia or Valsalva maneuvers can result in SNHL from LMR. Aberrant NO accumulation in the middle ear cavity during general anesthesia with subsequent LMR is also a potential etiology, as is excessive leakage of CSF causing a form of endolymphatic hydrops. There is no definitive treatment of postoperative SNHL, although middle ear exploration may be beneficial for suspected overpressure injury to the middle ear, causing a perilymphatic fistula. Corticosteroids have been beneficial in certain cases of idiopathic SNHL; however, its effectiveness for postoperative SNHL is undocumented.

Recurrent hearing loss after myelography treated with epidural blood patch

Transient hearing impairment is a known sequel after various procedures that result in loss of cerebrospinal fluid, such as lumbar puncture, spinal anesthesia and myelography. But persistent or recurrent hearing loss after dural puncture is a rare entity. We present a case with recurrent low-frequency sensorineural hearing loss after myelography. The patient was treated successfully by means of an epidural blood patch, although the conservative treatment was ineffective.

Sensorineural hearing loss after select procedures

Hearing is one of the most significant senses; therefore, any loss can be frightening. Previous studies have found that certain surgical and medical procedures can result in hearing loss. Cardiac surgical procedures are most commonly associated with hearing loss owing to the use of the cardiopulmonary bypass pump. Other noncardiac, nonotologic surgical procedures also may result in hearing loss. Additionally, medical procedures such as myelogram and lumbar puncture have been associated with hearing loss. Studies suggest that hearing loss can result any time cerebrospinal fluid is leaked. This report highlights the effect of dural puncture on hearing loss. The implication that any dural puncture procedure may result in a cerebrospinal fluid leak and subsequent hearing loss is a significant clinical topic. Perianesthesia nurses are advised to educate themselves and their patients regarding this complication.

Improvement of chronic hearing loss after shunt revision. A case report

BACKGROUND

Hearing loss after intracranial and spinal procedures involving cerebrospinal fluid loss is rarely reported in the literature. We report a patient who suffered from delayed hearing loss after cerebrospinal fluid shunting that improved after revising the shunt to a higher-pressure valve.

CASE DESCRIPTION

A 32-year-old woman presented with bilateral hearing loss 4 years after ventriculoperitoneal shunting for communicating hydrocephalus. Her otologic work-up revealed sensorineural hearing loss. In an attempt to improve her hearing, 6 years after the hearing loss began (10 years after the shunt was placed), she underwent a shunt revision in which her valve was changed to a higher-pressure device. After the procedure, she had a significant improvement in her speech discrimination and a mild improvement in her pure tone recognition. These changes were documented with serial audiograms.

CONCLUSION

Hearing loss after cerebrospinal shunting procedures is not always limited to the immediate postoperative period. It may be a late complication of cerebrospinal fluid diversion. Chronic hearing loss after ventriculoperitoneal shunting may be treatable by changing the valve to a higher-pressure device. The etiology of hearing loss from intracranial hypotension is briefly discussed.

Na+,K+-ATPase and Ca2+-ATPase activities in the cochlear lateral wall following surgical induction of hydrops

Na+,K+-ATPase and Ca2+-ATPase activities have not been studied quantitatively in the cochlea affected by endolymphatic hydrops. The present study was designed to measure quantitatively the Na+,K+-ATPase and Ca2+-ATPase activities in the cochlear lateral wall and the threshold of auditory brainstem response (ABR) for guinea pigs in the early stages (=2 months) of experimentally induced endolymphatic hydrops. A significant negative association was demonstrated between Ca2+-ATPase activity and the change in ABR threshold for hydropic cochleae (P=0.014), but not for control cochleae (P=0.123), although no such significant association was revealed between Na+,K+-ATPase activity and any change in ABR threshold for both hydropic cochleae (P=0.751) and control cochleae (P=0.352). A significant increase in Ca2+-ATPase activity in the cochlear lateral wall was observed for the hydropic ear, in which normal ABR thresholds were maintained, as compared to the control ear. On the contrary, a mild decrease in Ca2+-ATPase activity in the cochlear lateral wall was observed for the hydropic ear, in which ABR thresholds increased significantly. The present findings suggest that alterations of Ca2+-ATPase activity in the cochlear lateral wall may implicate disturbed calcium-homeostasis in the inner ear, resulting in hearing dysfunction in the early stages of experimentally induced endolymphatic hydrops.

Sudden sensorineural hearing loss after spinal surgery under general anesthesia

Two patients, ages 72 and 71, who underwent lumbar decompressive surgery for spinal stenosis, were evaluated for postoperative sudden sensorineural hearing loss (SSHL). After two uncomplicated spinal procedures, both patients developed SSHL immediately after surgery. Hearing loss was moderate to profound in these two patients. None of the patients had a significant otologic history. Nitrous oxide administration, Valsalva maneuvers during general anesthesia, and transient drops in cerebrospinal fluid pressure stemming from spinal decompression may, in some combination, lead to an implosive force on the inner ear, causing SSHL. Further causes of postlumbar surgery SSHL may include microemboli or viral infections. SSHL is a rare but possible complication after nonotologic, noncardiac bypass surgery; only 26 cases of SSHL after this surgery have been reported. We encourage the continued reporting of sudden sensorineural hearing loss after spinal surgery.

Persistent bilateral hearing loss after shunt placement for hydrocephalus. Case report

Transient hearing decrease following loss of cerebrospinal fluid (CSF) has been reported in patients undergoing lumbar puncture, spinal anesthesia, myelography, and/or different neurosurgical interventions. The authors present the first well-documented case of a patient with persistent bilateral low-frequency sensorineural hearing loss after shunt placement for hydrocephalus and discuss the possible pathophysiological mechanisms including the role of the cochlear aqueduct. These findings challenge the opinion that hearing decreases after loss of CSF are always transient. The authors provide a suggestion for treatment.

Do musical hallucinations always arise from the inner ear?

It has been known for some time that musical hallucinations occur in deaf patients. This has been ignored, as it has been believed that neurological and psychiatric causes predominate. However, despite specific appeals, no one with musical hallucinations and a lesion in the brain but not in the ear has been produced. The postulated otological basis is a hyperactive state of the ear, a slight endolymphatic hydrops or pre-Meniere's disease. The hallucinations probably develop out of rhythmic tinnitus. A review of all the very disparate states and diseases supposedly causing musical hallucinations shows that peripheral ear symptoms are always present. It therefore seems that they always have the same simple otological trigger.

The cochlear aqueduct in pediatric temporal bones

The cochlear aqueduct is a bony channel which contains the fibrous periotic duct and connects the perilymphatic space of the basal turn of the cochlea with the subarachnoid space of the posterior cranial cavity. Previous histological studies suggested that patency depended on age, whereas a more recent study showed no statistical correlation between age and patency. To clarify patency in pediatric cochlear aqueducts, we selected 21 temporal bones from 12 infants and children, varying in age from birth to 9 years, in which the cochlear aqueduct was fully visible on one histological section. Photographs were taken for documentation and the length and width of the orifice of the external aperture of the aqueduct at the scala tympani were measured and followed to the internal aperture at the subarachnoid space. The lumen of the duct was examined for mononucleated cells, blood cells and fibrous tissue. Measurements revealed that the mean length of the cochlear aqueduct was 4.6 mm (range, 2.4-10.7 mm), mean width of the external aperture was 484 microm (range, 225-869 microm), and mean width of the internal aperture was 1293 microm (range, 699-2344 microm). The mean diameter of the narrowest part (isthmus) was 151 microm (range, 75-244 microm). In all temporal bones the cochlear aqueduct was patent, with one exception. This latter temporal bone was from a 2-month-old girl with multiple intralabyrinthine anomalies, with the missing cochlear aqueduct believed to be due to an aplasia. Our results support prior measurements of the cochlear aqueduct and demonstrate a short and patent cochlear aqueduct in newborns. With growth, a significant increasing length of the duct was found.

Effect of craniotomy and cerebrospinal fluid loss on the inner ear. An experimental study

Craniotomy with cerebrospinal fluid (CSF) suction was performed on 18 guinea pigs to determine the effects on the inner ear morphology. Six control animals received anaesthesia only and 12 were operated on with a postoperative survival time of 1 or 24 h. The histologic examinations showed no signs of endolymphatic hydrops or injury to other structures in any of the animals. In 11 of the operated animals, red blood corpuscles were demonstrated in the perilymphatic space of the cochlea, the subarachnoid space, and the cochlear aqueduct (CA). After 1 h survival time blood had entered primarily the basal part of the scala tympani, but in the animals of 24 h survival time the blood was more abundant in both the scala tympani and the scala vestibuli indicating flow within the inner ear. The CA thus provides a pathway between the CSF and the whole of the perilymph through which noxious effects could take place.