A 58-year-old female comes in with a five-year history of pulsatile tinnitus in the right ear. She describes hearing her heartbeat in the right ear. This is more pronounced at night and with physical activity. In the last six months, she noticed a decrease in her hearing on that side as well. She denies hoarseness or difficulty swallowing. She used to smoke cigarettes in the past but quit about a year ago. Her examination shows redness in the lower two-thirds of the tympanic membrane (Fig. 1).
Diagnosis: Glomus Jugulare Tumor Eroding the Cochlea
Pulsatile tinnitus is a fairly frequent patient complaint that we encounter. While most of these patients do not have a worrisome cause to their problem, all patients with constant pulsatile tinnitus require a thorough evaluation. Intermittent pulsatile tinnitus that only occurs for a few minutes at a time is unlikely to be caused by a fixed lesion such as a tumor or an arteriovenous malformation. The evaluation starts with a history of when the problem started, how often it occurs, what makes it better or worse, if it is better or worse in certain positions, and whether it truly is synchronous with the patient's pulse. Finally, the clinician should explore the existence of other symptoms such as autophony, hearing loss, vertigo, sound-induced dizziness, or pressure- induced vertigo.
The next step in the process is a good examination. This ideally requires a microscopic examination of the tympanic membrane, auscultation of the neck and the mastoid using a stethoscope, and performing various maneuvers to see if the symptoms get worse. These include putting gentle pressure on the neck on the same side, having the patient bend forward with their head between the knees, and turning the head toward or away from the affected side. In this patient, a mass can be seen in the middle ear that appears red and pulsating. This indicates a vascular mass. All patients with pulsatile tinnitus require an audiogram. This patient was found to have a mixed hearing loss on the right ear as seen on her audiogram (Fig. 2).
While different authors have recommended various methods of workup, our general approach is to primarily rule out the more life-threatening problem, then concentrate on the quality of life related issues if the patient desires. We first start with obtaining an MRI of the internal auditory canal with gadolinium. Our MRI protocol includes one set of axial images through the brain post gadolinium to ensure no masses are present. Depending on the patient's history and symptoms, an MRA or MRV, which examines the arterial and the venous system of the brain, can be obtained. A venous problem will generally subside with gentle pressure on the neck or turning the head in one direction or the other. This compresses the internal jugular vein, which decreases the blood flow on that side and will extinguish the sound of the pulsatile tinnitus. Arterial problems will require a significant amount of pressure on the neck to reduce the flow to the carotid artery, which is not as easily compressible as the jugular vein.
In the presence of an abnormal middle ear exam, the work up is intended to evaluate the source of the middle ear mass. The most common red middle ear tumors are glomus tympanicum, glomus jugulare, and a middle ear adenoma. A CT of the temporal bone can help in distinguishing a tumor originating in the middle ear from one originating in the jugular foramen (e.g., glomus jugulare). The CT scan can also delineate the degree of bony destruction in the temporal bone caused by the tumor and show the status of the ossicles. Some clinicians obtain a CT scan of the temporal bone with and without contrast; this can distinguish whether or not the tumor penetrates the intracranial cavity. The normal CT of the temporal bones is best for visualizing subtle bony changes such as ossicular changes (Figs. 3-5). It cannot distinguish the brain from tumor and all soft tissues (brain, muscle, blood vessel, tumor) and fluids will appear similarly.
The disadvantage of a CT scan, with and without contrast, is that it requires double the amount of radiation to obtain the images. MRI is better at detecting soft tissue abnormalities and can distinguish middle ear and mastoid tumor from fluid caused by Eustachian tube or mastoid antrum obstruction. We generally prefer performing a CT of the temporal bone in addition to an MRI of the internal auditory with and without gadolinium enhancement. The only disadvantage of an MRI is the higher cost compared to a CT scan. However, the amount of additional information obtained from an MRI substantially increases our ability to counsel the patient on the treatment regimen and plan the surgical approach.
Traditionally, a glomus tumor of the jugular foramen was purely a surgical disease. Even in the most experienced hands, the surgery was fraught with complications, with a substantial percentage of patients losing function in at least one cranial nerve. Patients with extensive disease could lose function in cranial nerve IX and X, which travel just medial to the jugular bulb. This would cause substantial difficulty in swallowing, resulting in the need for long-term feeding through a gastrostomy tube. It would also lead to difficulty in handling saliva, resulting in the need for a tracheostomy in some patients. Because of these significant morbidities and improved technique in treating skull base tumors with stereotactic radiation, there has been a trend toward treating a significant number of these patients with stereotactic radiation (Otol Neurotol. 2011;32:834 http://bit.ly/2e7wXXp). This is especially seen in those with extensive tumors in the presence of normal cranial nerve function at presentation. Stereotactic radiation, such as GammaKnife or CyberKnife, usually stops the growth of benign tumors such as glomus tumors rather than shrink or destroy them completely. This is because radiation will only primarily kill cells that are actively growing and dividing. The bulk of benign tumors (such as glomus tumors) is made up of cells that are not actively dividing. These cells are not directly affected by radiation. The secondary effect of radiation occurs six to 12 months after the radiation has been delivered. This secondary effect leads to fibrosis and closure of blood vessels that feed the tumor, causing an infarction of some sections of the tumor. Therefore, radiation generally does not cause the pulsatile tinnitus or the conductive hearing loss to go away.
For patients with a substantial middle ear component in addition to large jugular foramen and temporal bone components, a combination of surgery for the middle ear and stereotactic radiation for the rest of the tumor is performed. This improves the conductive hearing loss and pulsatile tinnitus in addition to reducing the need for radiation to the middle ear and cochlea. This patient had erosion of the basal turn of the cochlea (Fig. 4), which was the likely cause of the sensorineural component of her hearing loss.
BONUS VIDEOS: VISUAL DIAGNOSIS
Read this month's Clinical Consultation case, then watch the accompanying videos from Hamid R. Djalilian, MD, to review the patient's imaging for yourself.
* Video 1. Video otoscopy of another patient with glomus tumor showing the pulsatile nature of the mass behind the tympanic membrane.
* Video 2. Axial CT images of the right temporal bone showing the tumor starting in the jugular bulb and infiltrating the temporal bone.
* Video 3. Axial CT images of the left temporal bone showing the normal anatomy with bone surrounding the cochlea and carotid artery.
* Video 4. Coronal CT of temporal bones showing tumor invasion from below the cochlea involving the basal turn. The normal left side (right side of the images) can be seen for comparison.
* Video 5. Axial soft tissue post contrast CT of temporal bones showing the tumor (bright) which abuts the intracranial cavity but has not caused a mass effect.
* Video 6. Sagittal post-contrast temporal bone CT showing the close relationship between the glomus jugulare tumor, cochlea, and carotid.
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