Otologic manifestations of benign intracranial hypertension syndrome: diagnosis and management

Non-pulsatile subjective tinnitus without hearing loss may be caused by undetectable sounds originating from venous system of the brain

Tinnitus is a common otologic symptom, which can interfere with the daily activities of life. Subjective tinnitus is perception of sound only heard by the patient. The most common type of tinnitus is non-pulsatile subjective tinnitus (NST), which is believed to originate from auditory pathway, mostly from central nervous system. This hypothesis proposes that an important percentage of NST cases are actually misdiagnosed venous type tinnitus cases. Recent studies have demonstrated that dural-jugular system is dominant only in the horizontal body position. Jugular flow is at maximum during this position possibly making any noise generated within the dural-jugular system louder. As body assumes more vertical positions it gradually leaves its function to the extrajugular venous system of the brain. When there is an objective and/or a pulsating sound it is easier to suspect a vascular etiology and diagnose it clinically or radiologically. However, if a vascular pathology causes a non-pulsatile complaint that can not be heard by the examiner or can not be detected clinically or radiologically, it is bound to be misdiagnosed as central tinnitus. Most NST cases experience their symptoms especially at night. Night time usually allows the combination of silent ambience and horizontal body position to take place. We believe that in some NST cases, especially those without hearing loss (HL), the main cause of tinnitus is venous in origin.

Bilateral hearing loss due to a meningioma located in the left posterior fossa: a case report

We report the case of a 39-year-old woman with a left side meningioma, suffering from bilateral sensorineural hearing loss, who recovered audiometric hearing in both ears after surgery. A preoperative pure tone audiogram (PTA) revealed a bilateral sensorineural hearing loss. Several examinations for sensorineural hearing loss indicated cochlear and retrocochlear hearing loss in the left ear and cochlear hearing loss in the right ear. After the operation, bilateral hearing loss due to a left posterior fossa meningioma gradually improved. One year after surgery, with the exception of hearing at frequencies of 4 and 8 kHz in the left ear, the postoperative audiogram had improved to an almost normal level. We speculate that hearing loss in the left ear may have been induced by the indirect compression of the cochlear nerve caused by the tumor's edema, whereas that in the right ear may have resulted from changes in CSF pressure caused by the mass effects of the tumor.

Adult spontaneous CSF otorrhea: correlation with radiographic empty sella

OBJECTIVE

To determine the prevalence of radiographic empty sella in patients with spontaneous cerebrospinal fluid (CSF) otorrhea.

STUDY DESIGN AND SETTING

Retrospective case series of adult patients with CSF otorhinorrhea at an academic tertiary medical center. Patients with history of skull base surgery, trauma, tumor, or chronic ear disease were excluded. Available imaging studies were reviewed with attention to the sella turcica.

RESULTS

Eight patients were diagnosed with spontaneous CSF otorrhea. Five of seven patients with adequate imaging studies (71%) had a radiographic empty sella. Seven of eight patients were clinically obese, with a body mass index BMI>30 kg/m2.

CONCLUSIONS

Empty sella is a common radiologic finding in patients with spontaneous CSF otorrhea. This supports the theory that increased intracranial pressure contributes to development of spontaneous CSF otorrhea.

SIGNIFICANCE

Radiographic empty sella predicts elevated intracranial pressure, which may require further evaluation and treatment in patients with spontaneous CSF otorrhea.

EBM RATING

C-4.

Idiopathic intracranial hypertension

OBJECTIVE

The history, diagnosis, and therapy of idiopathic intracranial hypertension (IIH) (pseudotumor cerebri) are reviewed. Theories of pathogenesis are considered, the clinical presentation is described, and potential diagnostic and therapeutic challenges are explored.

METHODS

An extensive literature review of IIH and related conditions (secondary pseudotumor syndromes) was performed. The history of and rationale for the diagnosis and medical and surgical approaches to treatment are reviewed. Available outcome studies are presented.

RESULTS

Diagnosis of IIH requires that the modified Dandy criteria be satisfied. Multiple potential contributing causes of intracranial hypertension must be identified or excluded. The clinical presentation most often includes headaches and papilledema, but many other findings have been described. The most important goal of therapy is to prevent or arrest progressive visual loss. Medical therapies include alleviation of associated systemic diseases, discontinuation of contributing medications, provision of carbonic anhydrase inhibitors, and weight loss. Surgical therapies include lumboperitoneal shunting, ventriculoperitoneal shunting, and optic nerve sheath fenestration. On the basis of the advantages and disadvantages of these treatment modalities, a suggested treatment paradigm is presented.

CONCLUSION

Idiopathic intracranial hypertension is the term to be adopted instead of pseudotumor cerebri. IIH remains an enigmatic diagnosis of exclusion. However, prompt diagnosis and thorough evaluation and treatment are crucial for preventing visual loss and improving associated symptoms.

Pseudotumor cerebri

Pseudotumor cerebri is a perplexing syndrome of increased intra-cranial pressure without a space-occupying lesion. The terminology for the disorder has changed over the years and the diagnostic criteria revised to reflect advances in diagnostic technology and insights into the disease process. The classification and nomenclature depend on the presence or absence of an underlying cause. When the diagnostic criteria are followed, a secondary etiology is unlikely. When no secondary cause is identified, the syndrome is termed "idiopathic intracranial hypertension."

Pulsatile tinnitus

Pulsatile tinnitus is an uncommon otologic symptom, which often presents a diagnostic and management dilemma to the otolaryngologist. This symptom always deserves a thorough evaluation to avoid disastrous consequences from potentially life-threatening associated pathology. In most pulsatile tinnitus patients a treatable underlying etiology can be identified.

Perilymphatic pressure measurement in Meniere's disease

The aim of this study was to evaluate the perilymphatic pressure, by means of the MMS-10 Tympanic Displacement Analyzer (TDA), in patients with Meniere's disease (MD). Measurements were performed in 37 patients with MD and in 14 normal-hearing subjects. Data were collected from 3 groups: healthy ears of normal-hearing subjects, unaffected ears of patients with MD, and affected ears of patients with MD. Analysis of the results obtained with the TDA showed no significant differences between the 3 groups. Several hypotheses could explain this lack of difference: 1) perhaps indirect measurement of perilymphatic pressure with the TDA is not relevant; 2) perhaps hyperpressure of the inner ear is not the physiological basis for the clinical triad of MD; or 3) perhaps endolymphatic hydrops does not produce changes in perilymphatic pressure. The results of this series indicate that the TDA is not useful in the evaluation of patients with MD.

Tinnitus

Tinnitus is a common otologic symptom secondary to numerous etiologies, such as noise exposure, otitis, Meniere's disease, otosclerosis, trauma, medications, and presbycusis. A thorough evaluation is necessary to rule out less common causes, which may include acoustic neuromas, glomus tumors, atherosclerosis of the carotid arteries, arteriovenous fistulae (AVFs), arteriovenous fistulae malformations (AVMs), and intracranial hypertension. Treating physicians need to have a very compassionate attitude towards these patients, and statements such as "there is nothing that can be done" are very inappropriate and should be strongly condemned. Reassurance, hearing aids, masking devices, retraining methods, antidepressants, intratympanic medications, and management of underlying pathologies such as carotid artery atherosclerosis, skull base tumors, intracranial hypertension, and AVMs/AVFs provide relief for the majority of these patients.

Role of angiography in the evaluation of patients with pulsatile tinnitus

OBJECTIVES/HYPOTHESIS

Pulsatile tinnitus in the face of normal findings on otoscopy is a common otological diagnostic dilemma and can be due to serious vascular malformations such as transverse or sigmoid sinus dural arteriovenous fistula (transverse or sigmoid sinus [TS] DAVF). Left untreated, TS DAVF may result in significant morbidity and mortality. TS DAVF can be suspected or diagnosed with computed tomography (CT), magnetic resonance imaging (MRI), and magnetic resonance angiography (MRA), with the gold standard being angiography. Our objective was to assess the utility of these various diagnostic modalities in the diagnosis of dural arteriovenous fistula.

STUDY DESIGN

Retrospective clinical review.

METHODS

Between 1986 and 1996, 54 patients were evaluated and treated for TS DAVF. Between 1996 and 1999, an additional 33 patients underwent MRI combined with MRA for the evaluation of pulsatile tinnitus. A retrospective review of the medical records for both groups, with special attention to clinical presentation, diagnostic evaluation, therapy, and outcome, was performed.

RESULTS

All patients had pulsatile tinnitus with normal findings on otoscopy. CT scan was relatively insensitive in the detection of TS DAVF. MRI and MR/MRA were significantly more sensitive than CT. In the evaluation of patients with subjective pulsatile tinnitus, MRI/MRA defined anatomical abnormalities that may contribute to pulsatile tinnitus in 63% of patients.

CONCLUSIONS

In the absence of objective pulsatile tinnitus, MRI/MRA is an appropriate initial diagnostic step. When a patient has an objective bruit, the clinician may choose to proceed directly to angiography to make certain that a TS DAVF is not missed.

Why monitor perilymphatic pressure in Menière's disease?

A cohort of 39 patients with confirmed raised intracranial pressure was investigated. Of these patients, 24 (62%) complained of tinnitus and 11 (28%) suffered from paroxysmal rotary vertigo. Intracranial hypertension can occur without the usual headache and visual symptoms. In such cases, the patient may be referred to the otolaryngological clinic and the condition may be mistaken for Menière's disease or a labyrinthine disorder. The Tympanic Membrane Displacement (TMD) technique now provides a non-invasive method of monitoring the intracranial and perilymphatic pressures. This study provides recommendations for the use of TMD techniques in the otolaryngological clinic for screening, diagnosing and monitoring treatment of patients presenting with raised perilymphatic pressure.

Non-invasive perilymphatic pressure measurement in patients with Menière's disease

The MMS-10 Tympanic Displacement Analyser in a new device to measure the perilymphatic pressure in humans. This instrument was used in 25 patients with Menière's disease (28 affected ears) and a group of 50 young normal hearing subjects. No significant differences were found in perilymphatic pressure measurements between the groups. Although measurement parameters showed large inter-individual variation, the intra-individual correlation was good. In patients with Menière's disease, no relationship was found between perilymphatic pressure, hearing threshold, blood pressure, gender or age.

Is perilymphatic pressure altered in tinnitus?

Tinnitus is characterized by the continuous or intermittent auditory perception of various sounds (buzzing, whistling, etc.) in the absence of any external stimulus. Perilymphatic hyperpressure is one of the numerous mechanisms which could hypothetically be involved in tinnitus generation. In the present experiment, perilymphatic pressure was measured indirectly using the tympanic membrane displacement technique. Twenty-five tinnitus patients were investigated at 10, 15 and 20 dB above the acoustic reflex threshold with ipsilateral stimulation. The variables Vi (inward tympanic displacement), Vm (mean tympanic displacement) and their variations according to stimulus level were compared between tinnitus sufferers and age-matched or hearing-matched controls. Tympanic displacement was measured in sitting and supine positions so as to evaluate cochlear aqueduct patency. No systemic changes in response occurred in tinnitus patients, except at a high stimulation level, perhaps due to hearing impairment.

Idiopathic intracranial hypertension

Although the cause of IIH remains obscure, it has become clear that loss of visual function is common and patients may progress to blindness. Diagnosis should adhere to the modified Dandy criteria. Recent case-control studies cast doubt on the validity of many frequently cited conditions associated with IIH. Valid associations include obesity, recent weight gain, female gender, vitamin A intoxication, and steroid withdrawal. IIH patient management should include serial perimetry using a sensitive disease-specific strategy. This is done so the proper therapy can be selected and visual loss prevented or reversed.

Bilateral cavernous sinus thrombosis causing Korsakoff's amnesic syndrome

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The prevalence of perilymphatic hypertension in subjects with tinnitus: a pilot study

This study investigated the prevalence of perilymphatic hypertension (raised perilymphatic pressure) in a population of subjects with tinnitus. A review of the literature showed how changes in perilymphatic pressure could affect tympanic membrane displacement measurements. This review also revealed that perilymphatic hypertension was more likely to occur in young females (less than 45 years) than in other subjects. An experiment was designed to test 32 subjects, who were divided into four groups according to their age and sex. These subjects underwent several routine audiological tests and were then tested with the tympanic membrane measurement system to determine the perilymphatic pressure of both ears. Statistical analysis of the experimental results showed that the young females had raised perilymphatic pressure. This was significantly higher than the perilymphatic pressure of the other test groups and of that of a normal population. The young females also exhibited other symptoms indicative of raised perilymphatic pressure. The raised pressure was thought to be due to an increase in fluid pressure which is more likely to occur in females due to variations in the levels of circulating hormones with menstrual irregularities, pregnancy and the menopause.

Diagnosis and treatment of arachnoid cysts of the posterior fossa

Arachnoid cysts of the posterior fossa are rare. When arachnoid cysts are encountered, the presenting symptoms are frequently otologic, with hearing loss and imbalance occurring commonly. Three cases are presented with a previously unreported otologic symptom, that of bilateral hearing loss, which in one case was fluctuant. None of the patients had the common symptoms of unilateral hearing loss and headache. With the advent of computed tomography and magnetic resonance imaging, these cysts may be readily identified, usually with diagnostic imaging alone. Unfortunately there is often a delay in diagnosis because of the vague and fleeting nature of the symptoms. Because no single diagnostic symptom pattern is able to characterize all cases, it is believed computed tomography or magnetic resonance imaging or both are indicated in patients with long-standing otologic complaints--even in the absence of unilateral symptoms. Treatment of posterior fossa arachnoid cysts primarily consists of surgical procedures designed to decompress the cyst. In this series, treatment with diuretics alone resulted in improvement of symptoms during several years of followup, with no evidence of enlargement of the cysts.

Cochlear and cerebrospinal fluid pressure: their inter-relationship and control mechanisms

The patency of the cochlear aqueduct is a key factor in intra-cochlear hydromechanics. If patent, the cerebrospinal fluid (CSF) provides the reference pressure for the perilymph and also to a large extent the endolymph, since Reissner's membrane can only withstand a relatively small pressure differential. The aqueduct often becomes sealed as a natural process of ageing. In this instance the reference pressure is from a source, its position unknown, within the boundaries of the cochlea itself. Relatively large and rapid changes in the cerebrospinal fluid pressure may result from everyday events such as coughing (ca. 175 mm saline) and sneezing (ca. 250 mm saline). The resistive nature of the cochlear aqueduct and the mechanical compliance of the cochlear windows are probably important factors in limiting the amount of stress, and therefore possible damage, which may occur to the cochlea and cochlear windows for a given pressure change within the CSF system. A narrow aqueduct and compliant cochlear windows reduce the risk of structural damage. In practice, this should mean that the risk of structural damage will be increased by any process which reduces the compliance of one or both of the cochlear windows, for example, extremes of middle ear pressure perhaps brought about by Eustachian tube dysfunction or rapid barometric pressure changes. Techniques are now available which provide non-invasive indirect measures of perilymphatic pressure and CSF-perilymphatic pressure transfer. The tympanic membrane displacement measurement technique has been used to provide reliable measures of perilymphatic pressure and CSF-perilymphatic pressure transfer on an individual subject basis.(ABSTRACT TRUNCATED AT 250 WORDS)

The relationship between intracranial pressure and tympanic membrane displacement

Transmission of intracranial pressure (ICP) to the perilymph of the cochlea may occur via the cochlear aqueduct and possibly other routes. Indirect measurement of perilymphatic pressure may be investigated by observing tympanic membrane (TM) displacement during stapedial reflex contraction. In a previous study we investigated the effects of changes in ICP on perilymphatic fluid pressure in three patients who underwent ventriculo/lumbar-peritoneal shunt operations. The TM displacement technique proved extremely sensitive and revealed marked changes in cochlear fluid pressure brought about by changes in ICP (Marchbanks et al., 1987). The study has been extended to 58 patients with hydrocephalus, intracranial tumours and other neurological conditions associated with abnormal ICP. Significant differences in the TM displacement were found between patients with raised and normal ICP. We have shown that changes in ICP can affect the hydrostatic pressure of the cochlea and influence the peripheral auditory system. The finding that ICP can be correlated with TM displacement strengthens the association between an abnormal TM displacement and abnormal cochlear hydrostatic status, irrespective of cochlear aqueduct patency. We suggest that the TM displacement technique provides a useful non-invasive method for the assessment of perilymphatic fluid pressure.