Perilymph fistula: the Stanford experience

Orthostatic hearing loss: audiovestibular manifestations of spontaneous intracranial hypotension

A 36-year-old woman with severe postural headaches caused by spontaneous intracranial hypotension developed bilateral hearing loss. Her hearing loss varied in severity and also at times affected one ear more than the other. She noticed her hearing returned to normal on lying flat, and this was confirmed on audiometry. Her hearing fully recovered after treatment with blood patches. Audiovestibular symptoms affect up to 70% of people with spontaneous intracranial hypotension but are probably under-reported. Cerebrospinal fluid and inner ear fluids are related in two separate channels: the vestibular and the cochlear aqueducts. We discuss their role in the postural hearing loss of spontaneous intracranial hypotension.

Perilymphatic Fistula: A Review of Classification, Etiology, Diagnosis, and Treatment

A perilymphatic fistula (PLF) is an abnormal communication between the perilymph-filled inner ear and the middle ear cavity, mastoid, or intracranial cavity. A PLF most commonly forms when the integrity of the oval or round window is compromised, and it may be trauma-induced or may occur with no known cause (idiopathic). Controversy regarding the diagnosis of idiopathic PLF has persisted for decades, and the presenting symptoms may be vague. However, potential exists for this condition to be one of the few etiologies of dizziness, tinnitus, and hearing loss that can be treated surgically. The aim of this review is to provide an update on classification, diagnosis, and treatment of PLF. Particular attention will be paid to idiopathic PLF and conditions that may have a similar presentation, with subsequent information on how best to distinguish them. Novel diagnostic criteria for PLF and management strategy for PLF and PLF-like symptoms is presented.

Recent surgical options for vestibular vertigo

Vertigo is not a well-defined disease but a symptom that can occur in heterogeneous entities diagnosed and treated mainly by otolaryngologists, neurologists, internal medicine, and primary care physicians. Most vertigo syndromes have a good prognosis and management is predominantly conservative, whereas the need for surgical therapy is rare, but for a subset of patients often the only remaining option. In this paper, we describe and discuss different surgical therapy options for hydropic inner ear diseases, Menière's disease, dehiscence syndromes, perilymph fistulas, and benign paroxysmal positional vertigo. At the end, we shortly introduce the most recent developments in regard to vestibular implants. Surgical therapy is still indicated for vestibular disease in selected patients nowadays when conservative options did not reduce symptoms and patients are still suffering. Success depends on the correct diagnosis and choosing among different procedures the ones going along with an adequate patient selection. With regard to the invasiveness and the possible risks due to surgery, in depth individual counseling is absolutely necessary. Ablative and destructive surgical procedures usually achieve a successful vertigo control, but are associated with a high risk for hearing loss. Therefore, residual hearing has to be included in the decision making process for surgical therapy.

Perilymph fistula: the patients' experience

OBJECTIVE

This study aimed to assess the experiences and outcomes of patients who underwent surgical repair of a perilymph fistula in Norfolk, UK.

METHODS

The study involved a retrospective questionnaire-based patient survey and case note review of patients who had undergone tympanotomy and perilymph fistula repair between 1998 and 2012 in two district general hospitals.

RESULTS

Fourteen patients underwent 20 procedures, of whom 7 completed the pre- and post-operative Vertigo Symptom Scale. In five patients, there was no obvious precipitating cause. Perilymph fistula was precipitated by noise in one patient, by a pressure-increasing event in six patients and by trauma in two patients. The Vertigo Symptom Scale scores showed a statistically significant improvement following surgical repair, from a median of 67 (out of 175) pre-operatively to 19 post-operatively.

CONCLUSION

In selected patients with vertigo, perilymph fistula should be considered; surgical repair can significantly improve symptoms.

Critical evaluation of round window membrane sealing in the treatment of idiopathic sudden unilateral hearing loss

Objectives

Rupture of the round window membrane with consecutive development of a perilymphatic fistula (PLF) is still a matter of controversial debate in the pathogenesis of idiopathic sudden sensorineural hearing loss (SSHL). Until now no consensus exists about whether these patients benefit from performing an exploratory tympanotomy with sealing of the round window. The aim of the present study was to analyze critically the effectiveness of sealing the round window membrane in patients with SSHL.

Methods

The clinical data of 51 patients with SSHL and a mean hearing decline of at least 60 dB over 5 frequencies who were treated with tympanotomy and sealing of the round window membrane were retrospectively analyzed. The results have been compared to the current state of the literature.

Results

Intraoperatively a round window membrane rupture or fluid leak was observed in none of the patients. After performing tympanotomy the mean improvement of hearing level was 32.7 dB. Twenty of 51 examined patients (39.2%) showed a mean improvement of the hearing level of more than 30 dB and a complete remission could be detected in 12 patients (23.5%). Reviewing the literature revealed no standard guidelines for definition or treatment of SSHL as well as for evaluation of hearing loss and its recovery.

Conclusion

The results of the present study and the literature should be discussed critically. It is unclear whether tympanotomy and sealing of the round window membrane may be a meaningful treatment for SSHL. Therefore this procedure should be discussed as a therapeutic option only in selected patients with sudden deafness or profound hearing loss in which PLF is strongly suspicious or conservative treatment failed.

A balance test for chronic perilymph fistula

Perilymph fistula is defined as a leak of perilymph at the oval or round window. It excludes other conditions with "fistula" tests due to a dehiscent semicircular canal from cholesteotoma and the superior canal dehiscence syndrome. First recognized as a complication of stapedectomy, it then became apparent that head trauma and barotraumatic trauma from flying or diving could be a cause. Descriptions of "spontanenous" perilymph fistulas with no trauma history followed. It is likely that most perilymph fistula patients have a congential potential weakness of the otic capsule at the round or oval window. The vestibular symptoms have been assumed to be due to endolymphatic hydrops, but there is poor evidence. Their unilateral disequilibrium, nausea, and subtle cognitive problems suggest they are due to otolith disfunction and that these patients have a specific balance abnormality, unlike subjects with unilateral vestibular hypofuction. In this series of twenty patients with a confirmed fistula a logical simplification of Singleton's "eyes-closed turning" test predicted a PLF in twelve with a trauma history. In four no cause was found. In three a prior traumatic event was later recalled, but one patient had concealed it.

Perilymph fistula: fifty years of controversy

Perilymph fistula (PLF) is defined as a leak of perilymph at the oval or round window. It excludes other conditions with "fistula" tests due to a dehiscent semi circular canal from cholesteatoma and the superior canal dehiscence syndrome. It was first recognized in the early days of stapedectomy as causing disequilibrium and balance problems before sealing of the stapedectomy with natural tissue became routine. It then became apparent that head trauma and barotraumatic trauma from flying or diving could be a cause of PLF. Descriptions of "spontaneous" PLF with no trauma history followed. A large literature on PLF from all causes accumulated. It became an almost emotional issue in Otolaryngology with "believers" and "nonbelievers." The main criticisms are a lack of reliable symptoms and diagnostic tests and operative traps in reliably distinguishing a perilymph leak from local anaesthetic. There are extensive reviews on the whole topic, invariably conveying the authors' own experiences and their confirmed views on various aspects. However, a close examination reveals a disparity of definitions and assumptions on symptoms, particularly, vestibular. This is an intentionally provocative paper with suggestions on where some progress might be made.

Retrocochlear mass lesion in mid-frequency sudden deafness

Objective

This study retrospectively reviewed all cases of mid-frequency sudden deafness to understand the clinical significance of this hallmark finding.

Study Design

Retrospective study.

Subjects and Methods

From 1992 to 2006, a total of 556 patients with sudden deafness were experienced. Based on the audiographic configuration, these patients were classified into: flat-type group, 272 cases; high-frequency group, 146 cases; low-frequency group, 70 cases; mid-frequency group, 30 cases; and unclassified group, 38 cases. All patients underwent a battery of audiovestibular function testing.

Results

Among 556 sudden deafness patients, 17 patients (3%) were proved to have a retrocochlear tumor, including mid-frequency group (10), high-frequency group (4), flat-type group (2), and low-frequency group (1). Thus, the mid-frequency group had significantly higher (33%) association with a retrocochlear tumor than other groups.

Conclusion

One-third of the patients with mid-frequency sudden deafness harbor a true retrocochlear mass lesion; hence, MR imaging is mandatory in such cases.

[Perilymphatic fistula: diagnosis and treatment]

INTRODUCTION

Diagnosis and management of perilymphatic fistula (PLF) is a controversial topic in the international neurotologic literature. An illustrative case of post traumatic PLF with clear surgical indications is presented. This manuscript also reviews the various clinical presentations, pathogenesis, diagnostic examinations, and management options of PLF.

MATERIALS AND METHODS

Case report and literature review.

RESULTS

A 40 y/o female presented with paroxysmal vertigo, imbalance and severe sensorineural hearing loss (SNHL) following minor occipital head trauma from a fall six months prior to presentation. Laboratory examination included intermittently positive fistula sign on video-nystagmography. Patient failed to respond to trials of pharmacologic treatment and bedrest and ultimately underwent surgical exploration and repair. Patient had earlobe fat placed in the round and oval windows. Postoperatively, she had prompt resolution of vestibulopathy and ultimate full return of sensorineural function.

CONCLUSIONS

Patients with appropriate antecedent history demonstrating fluctuating SNHL and vestibulopathy, failing to respond to conservative medical treatments, should be considered for exploratory tympanotomy. In the absence of any other violations of labyrinthine integrity, connective tissue grafting of the round and oval windows should be performed even if no obvious flow of fluid is observed. This management protocol is safe and effective in properly selected patients.

Noise-Induced Perilymph Fistula

Perilymph fistulae are difficult to diagnose because they present with a wide variety of signs and symptoms, they are associated with many etiologies, and they often mimic other conditions. In this article, we describe a case of perilymph fistula that featured one of its more rare causes: acoustic trauma—specifically, damage from a loud blast from the siren of a fire engine. We also review the literature and discuss the difficulties of diagnosis and treatment and the possible mechanisms by which acoustic trauma and other etiologies cause perilymph fistulae.

Outcome of hearing and vertigo after surgery for congenital perilymphatic fistula in children

PURPOSE

To determine if surgery to repair a perilymphatic fistula (PLF) has any significant morbidity and to determine the outcome of the surgery in regards to hearing and vertiginous symptoms.

MATERIALS AND METHODS

A retrospective study was performed with all patients undergoing PLF repair at a tertiary medical center. Each patient was assessed for comparison of their pre- and postoperative hearing levels, vertiginous complaints, and recurrences.

RESULTS

One hundred sixty ears were operated on for PLF over a 13-year period. Of the 103 ears positive for PLF, 92% either stabilized or improved their hearing and 3% noticed a decrease, but this was well after surgery and not believed to be related. These results were similar in the non-PLF ears in which 95% had stabilized or improved hearing and again 3% had a much delayed decrease. Of the children who had vertiginous complaints before surgery, 91% were improved or stable. Only 1 child felt somewhat worse, but, as in the hearing loss, this was greater than 6 months after the surgery.

CONCLUSIONS

Surgical repair of PLF does not result in a significant risk for postoperative hearing loss or additional vertiginous complaints. Surgical repair may prevent further deterioration of hearing loss even in those patients in whom a PLF was not identified at the time of surgery.

Dextran-induced pulmonary edema in patients with sudden deafness

OBJECTIVE

Pulmonary complication in cases of sudden deafness after dextran treatment is rarely reported. This study discusses the management of two cases and reviews the current literature.

PATIENTS

Two (1%) of 204 patients with sudden deafness patients had fever, cough, and dyspnea after intravenous dextran infusion. Pulmonary edema was diagnosed after chest radiographic examination.

RESULTS

After interruption of dextran, subsequent supportive treatment relieved chest discomfort and fever without any sequelae. The results of chest radiograph and laboratory studies, including hemogram, renal function, and arterial blood oxygen saturation, were normal.

CONCLUSIONS

Patients receiving dextran treatment should have their clinical symptoms, renal function, chest radiographs, hemogram, and coagulation profiles monitored. If fever, bleeding, cough, or dyspnea occurs during treatment, dextran must be immediately stopped. Subsequent treatment should focus on dextran clearance to prevent further cascade complications.

Perilymph fistula--45 case analysis

PURPOSE OF THE STUDY

Though perilymph fistula (PLF) is not a rare disease, preoperative diagnosis still remains to be established. Some new diagnostic methods are challenging, but there is still no established diagnostic method except exploratory tympanotomy that verifies the occurrence of leakage. Early diagnosis of PLF is fully depending on history taking and some clinical examinations. To know the clinical features of PLF is one of the greatest helps to make both earlier and accurate diagnosis. In spite of some innovations in clinical examinations classic diagnostic procedure is thought to be still reliable.

PROCEDURES

We investigated the clinical symptoms, basic tests results and therapeutic results in patients with PLF.

RESULTS

From 1983 to 1998 PLF was identified in 44 patients (45 ears) with exploratory tympanotomies in our hospital. With respect to clinical history the predisposing factors such as blowing the nose, lifting heavy goods, and landing in an airplane were found in almost half of the patients, while the rest of them had no clear inducing factors. Their major symptoms included hearing loss (93%), vertigo and dizziness (91%), tinnitus (76%), and aural fullness (31%). The patients who have a clear predisposing factor tended to make diagnosis easily; on the other hand the rest of the patients who do not have clear etiology had some diagnostic difficulty. Subjective positive fistula signs were observed in 71% of patients. Vestibular symptoms improved in 80% of patients after closure of PLF.

CONCLUSIONS

These results suggest that the variety of clinical manifestation make diagnosis more difficult. At the moment meticulous clinical history taking and close follow-up applying repeating fistula tests are the most important for not only earlier but also accurate diagnosis.

Efficacy of vestibular rehabilitation

This article is a summary of the research on the effectiveness of vestibular rehabilitation in patients with vestibular disorders. The literature on patients with peripheral, central, combined peripheral and central disorders, and panic and anxiety disorders is reviewed. The positive outcomes of intervention are highlighted.

Perilymphatic fistula: a Washington, DC, experience

One hundred ninety-seven patients who underwent surgical repair for a presumed unilateral perilymphatic fistula were reviewed. Of those patients, 87% with vestibular symptoms reported complete or near-complete relief of their symptoms. Forty percent of the patients with sudden hearing loss had an improvement in their hearing levels. An analysis of several diagnostic tests revealed their sensitivity and specificity ratings. A review of the patients' operative records showed a marked disparity between the visual identification of an actual fluid leak during surgery and their postoperative outcome. This review supports the premise that at the present time, the patient's surgical outcome is the best way of documenting a successfully repaired perilymphatic fistula.

Sudden sensorineural hearing loss after general anesthesia for nonotologic surgery

Sudden sensorineural hearing loss (SNHL) is a well-recognized phenomenon that is attributed to a variety of etiologies. Sudden SNHL after cardiopulmonary bypass surgery has been well reported and is thought to be due to microemboli. However, a review of the English literature revealed only 15 cases of SNHL after general anesthesia for nonotologic surgery. Several etiologies for this loss have been suggested, but no proven pathogenesis is yet available. This report adds to the literature three additional cases of sudden SNHL after general anesthesia for nonotologic surgery. The literature is reviewed and proposed mechanisms of injury are discussed.

Head trauma: hearing loss and dizziness

OBJECTIVE

Because the physicians who care for patients with head trauma may be family practitioners or internists, this article provides these physicians some knowledge of the causes and pathophysiology of such trauma with respect to neurologic sequelae to aid in their decisions to seek consultation with neurologists and otoneurologists in diagnosis and management.

METHODS

This article reviews the literature concerning differential diagnosis, appropriate evaluation, and possible treatments of patients who exhibit hearing loss and dizziness after head trauma, whiplash injuries, or both. I also relate those findings to my extensive experience with such neurologic problems.

FINDINGS

The findings are grouped according to injuries that cause dizziness, including trauma to the brain stem - eighth nerve complex, the semicircular canals (labyrinthine concussion), benign paroxysmal positional vertigo, Meniere's syndrome -- vestibular symptoms, perilymphatic fistula -- vestibular symptoms, and cervical vertigo; and those that cause hearing loss, including trauma to the brain, eighth nerve, middle ear, cochlear concussion, Meniere's syndrome, and perilymphatic fistula.

Persistent dizziness following head trauma and perilymphatic fistula

A growing body of evidence supports the idea that dizziness that persists for months and even years can be caused by an unsuspected perilymphatic fistula. Perilymphatic fistulas are abnormal ruptures that allow perilymph to leak out of the inner ear into the middle ear space. Most commonly, these ruptures occur secondary to a traumatic event. The term postconcussive syndrome has been used to describe a myriad of symptoms following head trauma. Some of these symptoms, such as cognitive changes, tinnitus, neck stiffness, and dizziness, are also commonly caused by active perilymphatic fistulas. This article discusses the typical history and diagnostic tests for patients with perilymphatic fistula. Common diagnostic tests include audiograms, electronystagmograms, electrocochleograms, and subjective and platform fistula tests. Also, the surgical treatment for the perilymphatic fistula (ie, repair of the oval and round windows) is reviewed, along with the results produced by this relatively minor ear operation. Suggestions are made to help the medical professionals involved in rehabilitative care to be aware of perilymphatic fistulas and seek proper consultations from inner ear specialists if they suspect the existence of this easily cured disorder.

Beta 2-transferrin confirms perilymphatic fistula in children

beta 2-Transferrin is a protein that is unique to the cerebrospinal fluid and aqueous humor. On the basis of this information and a recent study from our institution that demonstrated that beta 2-transferrin was also unique to human perilymph, a prospective, double-blind study to evaluate perilymphatic fistula in children was performed. Attending otolaryngologists at Children's Hospital of Pittsburgh evaluated and recommended surgery for 10 children (10 ears) who were suspected of having a congenital perilymphatic fistula. During the operation, the surgeon decided whether a perilymphatic fistula existed, on the basis of otomicroscopic findings, and then separate pieces of gelatin sponge were placed on the oval and round windows, respectively, and sent to the immunopathology laboratory where they were analyzed for beta 2-transferrin. Ten patients (10 ears) undergoing tympanoplasty or tympanomastoidectomy were used as controls and tested in a similar fashion. During the study, both the surgeons and patients were blinded from the results of the test. Of the 10 control patients, none was observed to have a perilymphatic fistula, and all were negative for beta 2-transferrin. Of the 10 patients undergoing exploratory tympanotomy for perilymphatic fistula, 1 ear was thought to be negative for perilymphatic fistula on microscopic visual examination, whereas 9 were considered to be positive for perilymphatic fistula. No beta 2-transferrin was identified from the ear that was considered not to have a perilymphatic fistula, whereas six of the nine ears that were thought to have perilymphatic fistula tested positive for beta 2-transferrin.(ABSTRACT TRUNCATED AT 250 WORDS)

Occupational perilymph fistula

A case of occupational perilymph fistula in an ironworker is described. The patient was lifting and lowering 200 pounds of steel when he developed sudden onset of vertigo. Surgical exploration of the middle ear demonstrated leakage of perilymph fluid from the round window. Grafting of the window led to improvement of symptoms, but the patient was unable to continue work as an ironworker due to difficulty with balance.

Postoperative recurrence of perilymphatic fistulas

Postoperative follow-up study of perilymphatic fistulas (PLFs) showed that recurrence of PLF was not rare and revision was sometimes needed to relieve the symptoms associated with leakage of perilymph. Of the 54 PLF patients surgically treated in our clinic, some sign or symptom of recurrence was found in 9 cases (17%). Vertigo accompanied by spontaneous or positional nystagmus was noted in all 9 cases, while only 3 complained of exacerbation of the existing hearing loss. Revision was indicated in 3 patients since they had no predisposition to spontaneous healing. Various etiological and underlying factors contributed to the incidence of recurrence. Careful operative procedures together with strict postoperative management are required for surgical treatment of PLF.

Clinical characteristics and hearing recovery in perilymphatic fistulas of different etiologies

Clinical features and hearing recovery were compared between three types of perilymphatic fistula groups; surgically confirmed (PLF-conf, n = 16), suspected (PLF-susp, n = 24) and traumatic (trauma-PLF, n = 11). Initial average hearing level was best in the PLF-susp group (50.9 dBHL), followed by the trauma-PLF (55.7 dBHL) and PLF-conf (59.7 dBHL) groups, though the difference was not significant (ANOVA, p > 0.05). Of 51 patients, 27 cases were operated on and fistula was confirmed in 19 ears (70.4%). Conservative treatment, including bed rest and medication, was given to all patients. After the treatment, meaningful hearing recovery was obtained only at 1 kHz in the PLF-conf group (paired t-test, p < 0.05). However, significant recovery was seen at all frequency ranges (0.125-8 kHz) in the PLF-susp group (average, 16.8 dB; p < 0.01), while hearing improvement was intermediate for the trauma-PLF group. The initial hearing level and the period until the start of treatment strongly correlated with the final hearing level. Although 27 patients (47%) complained of dizziness, the prognosis for vertigo is excellent as noted by other authors. It was concluded that if conservative treatment is started early for PLF patients with mild hearing loss, hearing recovery can be ensured.

Congenital perilymphatic fistula and associated middle ear abnormalities

To specifically determine the frequency and type of middle ear abnormalities associated with perilymphatic fistula (PLF), a retrospective chart review was performed of 94 patients (117 ears) who underwent exploratory tympanotomy for PLF from 1980 to 1989. Of the 117 ears explored, 80 (68.4%) had a PLF, and in 65 (81.3%) of these ears, a middle ear malformation was associated with the PLF. Of these 65 ears in which a congenital middle ear abnormality was observed, a malformed stapes was the most common abnormality seen (39 ears, 60%), followed by a deformed round window (20 ears, 30.8%), a deformed incus (11 ears, 16.9%), and a deformed promontory (2 ears, 3%). Often these malformations coexisted amongst themselves or with inner ear abnormalities. Sixteen children (25 ears) had an inner ear malformation identified on computed tomography (CT); all of these children had a PLF found at the time of surgery. This study demonstrated that 86.3% of the ears found to have a PLF had a deformity of the middle ear, inner ear, or both. A malformation of the stapes, most frequently identified as a deformity of its superstructure (and presumably also the anterior footplate), was the most common congenital middle ear abnormality found to be associated with PLF in children.

Chronic perilymph fistula in the guinea pig with implications in the human

To improve understanding of the pathophysiology of perilymph fistulas, a predictable animal model of a chronic fistula was developed. Our findings suggest that guinea pig fistulas do not remain patent for prolonged periods. By extrapolating these findings to humans, we postulate that the symptoms and signs of perilymph fistula are possibly due not to one prolonged constant fistula, but rather a series of "blowouts" from an inherent congenital or posttraumatic weak spot in either the round or oval window. We feel that a diagnosis of perilymph fistula must be considered in any patient presenting with a Meniere's-like symptom set concomitant with a congenital inner ear deformity or a history of inner ear trauma.

Perilymphatic fistula: analysis of free amino acids in middle ear microaspirates

High-performance liquid chromatography was used to determine 19 free amino acid concentrations in perilymph, serum/plasma, and red blood cell intracellular fluid. Significant differences were found between perilymph and these fluids. Free amino acid analysis was then used to quantitatively analyze middle ear microaspirates in order to test the hypothesis that perilymph is a potential source of clear fluid in perilymphatic fistulas (PLF). Fourteen unknown samples from patients with visually identified PLF, including patients with no identifiable otic capsule defect, were studied. Six samples on amino acid pattern analysis were correlated most similarly with perilymph (rrho greater than 0.95). Four of these six samples were scored on the basis of quantitative amino acid values as similar to perilymph. However, three samples of clear fluid were more similar to serum/plasma than to perilymph on both amino acid pattern and quantitative amino acid score analysis. These results objectively suggest perilymph as a potential source of clear fluid in some patients with a diagnosis of PLF. Not all clear fluid observed in the middle ear, however, is potentially perilymph.

Perilymph fistula--a diagnostic dilemma

A retrospective series is presented of 51 cases operated on for suspected perilymph fistula. In 26 ears a fistula was identified at surgery. A positive fistula test was found to strongly indicate a perilymph fistula but was more often negative than positive in surgically demonstrated fistula ears. Other vestibular tests were found to be of little value in the pre-operative diagnosis. Ears with a surgically demonstrated fistula and sensorineural hearing loss had either flat or downward-sloping audiograms. Difficulties in diagnosing a perilymph fistula at tympanotomy are discussed. At follow-up, vestibular symptoms were found to be eliminated or improved in 96 per cent of cases with surgically demonstrated fistulae and in 68 per cent of cases in which no fistula was detected at tympanotomy but hearing improved significantly in only one ear (4 per cent) of the former group and in five ears (20 per cent) of the latter group.

Identification of perilymph proteins by two-dimensional gel electrophoresis

Perilymph has a total protein component that is quantitatively distinct from serum and cerebrospinal fluid (CSF). The goal of this research was to determine if perilymph contains any qualitatively unique protein constituents that will distinguish it from serum or CSF. To test this hypothesis, matched sets of perilymph, serum, and CSF were obtained from 18 guinea pigs and seven human subjects. The purity of each sample was assured by measurement of the protein concentration of each sample and comparison of this parameter to known normal values for perilymph, serum, and CSF. Each sample was then subjected to two-dimensional gel electrophoresis, separating proteins by isoelectric point in the horizontal dimension and by relative molecular weight in the vertical dimension. All gels were processed under precisely identical physical conditions by use of a diamine silver stain. A small number of perilymph proteins not found in plasma were identified in both the guinea pig and the human specimens. The finding of unique perilymph proteins may permit the development of a sensitive marker that will aid in the diagnosis of perilymph fistula.

Free amino acid analysis of guinea pig perilymph: a possible clinical assay for the PLF enigma?

Controversy prevails regarding the accuracy of the clinical diagnosis of perilymphatic fistula (PLF). The diagnosis of PLF has been based on the subjective evaluation of vestibular function tests and the intraoperative macroscopic visualization of "clear fluid" from the oval/round windows at the time of exploratory tympanotomy. However, the subjective visual characterization of PLF varies among observing surgeons. Furthermore, perilymph can be "contaminated" with serum, blood, cerebrospinal fluid (CSF), and local anesthesia. This article presents a scientific biochemical microassay for the free amino acid profile of perilymph. Microaliquots of uncontaminated perilymph were sampled from the bilateral round windows (scala tympani) of 20 guinea pigs and analyzed for 19 free amino acid concentrations (FAAC) by high-performance liquid chromatography (HPLC). These samples were compared with the FAAC of guinea pig serum samples. Perfect predictor value ranges were nonoverlapping for 12 of 19 free amino acids in perilymph vs. plasma. Amino acid microassay of middle ear fluid for verification of "true" perilymph vs. nonperilymph fluids by the identification of nonoverlapping FAA markers may allow scientific verification of the existence of PLF in "suspected" patients.

Bilateral spontaneous perilymph fistulae: a diagnostic and management dilemma

In this article, we present a case of bilateral perilymph fistulae. This entity is rare and always presents a diagnostic problem. Bilateral perilymph fistulae are more common in children and should be suspected when bilateral ear symptoms and congenital temporal bone radiographic anomalies are present. Previous trauma or barotrauma may be absent. When a patient manifests bilateral ear symptoms and a fistula has been identified and repaired in one ear, a second fistula should be suspected in the contralateral ear, especially if the fistula test is positive.

Summating potential/action potential ratio in perilymph fistula

A prospective study of electrocochleography in patients with clinically suspected perilymph fistula was undertaken to determine its predictive value in that disorder. One hundred forty-four patients suspected of having perilymph fistula had electrocochleography performed--34 of these (39 ears) had exploratory tympanotomy. Of the 19 ears with normal preoperative summating potential/action potential (SP/AP) ratio, ten had perilymph fistula identified at the time of surgery. Of the 20 ears with abnormal SP/AP ratio, 16 had perilymph fistula confirmed at exploration, 18 had resolution of symptoms after oval window and round membrane grafting, and only one ear had postoperative persistence of the abnormal SP/AP ratio. This study suggests that an abnormal SP/AP ratio is not only predictive of endolymphatic hydrops, but also of perilymph fistula (both problems of inner ear fluid imbalance). This study also suggests that, while abnormal SP/AP ratio is fairly specific for inner ear fluid imbalance, it is not sensitive.