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How to cite this article Sanchez TG, Santoro PP, í , Medeiros tRT, Bittar RSM, Bento RF. Pulsatile tinnitus (PT) is a perception of a rhythmical sound that is synchronous with the heartbeats. Pulsatile tinnitus (PT) is a rhythmical auditory sensation that is synchronous with a patient's heartbeat [1]. On 1882, Jacobson [4] was the first to describe a case of auditory sensation of cranial murmur associated with atherosclerosis. Since the establishment of the magnetic resonance angiography (MRA) technique, many vascular abnormalities have been identified, representing a great advance in many areas of medical science, including otoneurology.
Our prospective study was conducted at the tinnitus ambulatory unit of the Ear, Nose, and Throat Department of the University of Sao Paulo from January 1995 to June 1997. To rule out systemic causes of PT, such as anemia and hyperthyroidism, a clinical investigation always was accomplished that emphasized the following examinations: complete blood cell count, total cholesterol level and fractions, glucose test (test of tolerance to oral glucose when necessary), levels of triglycerides and thyroid hormones, and serological reaction for syphilis. Besides a complete audiometric evaluation, all patients underwent magnetic resonance imaging (MRI) with complementary MRA. Of the 13 patients with altered MRA, 9 (69.23%) presented with at least one variation of the vascular anatomy of the skull, which, in most cases, was closely correlated with the side on which PT occurred. Generally, PT is the otologic manifestation of a blood flow abnormality of the temporal bone.
The importance of investigating PT is justified by its higher association with identifiable and treatable causes, as compared to the common types of subjective and nonpulsatile tinnitus.
The most common causes of PT described in the literature are dural arteriovenous malformations and fistulas [3, 5, 6, 8-10].
According to Brodal [14], "In Neurology, a knowledge of structural features is perhaps more important for an understanding of function under normal and pathological conditions than in any other branch of medicine.
The subclavian arteries give rise to their first branches, the vertebral arteries (VAs), which commonly present variations [17].
Often, the intracranial portion of the vertebral arteries (ICVAs) are asymmetrical; one may be two to three times the size of the contralateral VA, with the left ICVA more often the larger. Evaluating the MRA of the 13 patients with any alteration, we noticed that 9 (69.23%) presented with variations of the arteriovascular anatomy of the skull only. Though the anatomical variation is congenital and PT seems to appear only in adulthood, we still need to determine the predisposing factors that trigger the appearance of tinnitus.
Clinical diagnosis of PT is based on a complete neurootological evaluation, which includes clinical history, complete physical examination (with special attention to the otoscopic examination), auscultation of the external auditory canal and adjacent areas, and palpation of the high cervical area and preauricular region [1, 5]. Computed tomography (CT) allows diagnosis of bone alternations associated with vascular anomalies [1, 6]. Arteriography is more sensitive than is CT, allowing the diagnosis of arteriovenous fistulas and intrinsic vascular anomalies. Due to its poor resolution for vascular and bone structures, the benefit of MRI used alone is limited.
MRA offers additional information and is superior to MRI alone; hence, arteriography is preferable in almost all cases. This work was presented at the 1998 Annual Meeting of the American Academy of Otorhinolaryngology, Head and Neck Surgery, San Antonio, TX, September 13-16, 1998. External and middle ear diseases: Radiological diagnosis based on clinical signs and symptoms. Computed tomography and magnetic resonance imaging of pathologic conditions of the middle ear. Despite being seen rarely in daily practice, frequently it is associated with identifiable causes, thus warranting special attention in regard to the etiological diagnosis.
Despite being seen only rarely in daily practice, frequently it is associated with identifiable causes, thus warranting special attention as regards the etiological diagnosis. Often, however, this vascular tumor presents with a reddish retrotympanic mass [6] in the otoscopic examination, which strongly suggests the correct diagnosis [2, 7].
Since 1936, many authors have described cases of PT associated with several such etiologies as vascular abnormalities [10], venous hum [11], tumors of the cerebellopontine angle, a high jugular bulb, dehiscent internal carotid artery (ICA) [3,7], and described arteriovenous malformations [7].
Considering the high incidence of identifiable and treatable causes of PT, the correct etiological diagnosis is fundamental.
The examinations always were performed by the same radiologist, using the team-of-flight, three-dimensional spin-echo technique, with T1- and T2-weighted sequences. Synchronous with cardiac pulsation [1, 7, 12], PT can reach high intensity and become a reason for psychological disability in some patients [3, 13].
In addition, misdiagnosis can be catastrophic, as PT can be related to intracranial diseases, including aneurysms and tumors [12, 13]. These are followed in frequency by paraganglioma, a vascular tumor that may correspond to the tympanicum, jugulare, or jugulotympanic glomus [2, 7]. According to our results, MRA was able to identify the cause of the PT in 81.25% of affected patients (13 of 16). The determination of the site of the lesion is therefore an important link in understanding the nature of the disease." The need to understand variations of the vascular anatomy and the need for applying this understanding has increased.

More than in any other region, accurate diagnosis depends on an intimate familiarity with the brain and vascular anatomy [16]. The VAs, more often the left, may arise directly from the aortic arch (approximately 8%), whereas the right VA may originate directly from the innominate artery. The four most important branches of the ICVAs are the anterior and posterior spinal arteries, the PICAs, and the direct lateral medullary branches. No previous report in the literature addresses the correlation between such anatomical variation and PT.
Equally important is evaluating an eventual papilledema, which leads to the diagnosis of benign intracranial hypertension syndrome [5].
Initially, definition of the radiological approach depends on knowing the nature of the PT (objective or subjective) and the aspect of the tympanic membrane. High-resolution CT is the appropriate examination to be requested in patients with retrotympanic masses, allowing one to diagnose such conditions as paragangliomas, aberrant ICA, and abnormalities of the jugular bulb. On the other hand, it is an invasive examination, with a considerable related morbidity index in some series [6]. Without contrast enhancement, it is not sufficient to differentiate some vascular tumors from arteriovenous malformations or to identify regions of vascular compressions, thereby limiting its use in patients with PT. It increases the ability to diagnose lesions responsible for PT, mainly dural arteriovenous malformations and fistulas [1, 5, 6].
In their present study, the authors point to variations of the vascular anatomy of the skull as a possible cause of PT.
Temporal bone imaging is challenging and involves deep understanding of the anatomy, especially in relation to High Resolution Computed Tomography (HRCT) imaging. PT results from blood flow turbulence, which in turn results from changes in flow velocity or in the vessel lumen. PT originates mainly in vascular structures (venous or arterial vessels) as a result of flow turbulence caused by increased blood volume or alterations in the vessel lumen [2-5]. We are not aware that the literature contains any report regarding the correlation between PT and anatomical variations of the arteries close to the skull base.
Therefore, the objective of our study was to evaluate the effectiveness of MRA in establishing the etiological diagnosis of PT. Axial acquisitions and saggital reconstructions were performed without the use of endovenous contrast.
Thirteen of 16 examinations (81.25%) presented alterations of the vessel lumen or of the velocity of blood flow (or both), includ-ing intracranial aneurysms in 2 patients and intracranial hypertension due to Arnold-Chiari syndrome in 1 patient. A paraganglioma presents with a vascular retrotympanic mass, which is an important sign for the physician, strongly suggesting the diagnosis [6]. Interestingly, we noted that the most common established cause of PT was anatomical variation of the vascular anatomy of the skull, which has not heretofore been described in the researched literature. The variability of the vascular anatomy, although "normal," represents increased rigidity of the system. The vascular supply of posterior circulation is from the paired subclavian- vertebral arteries, which join intracranially to form the basilar artery, which in turn bifurcates into the paired posterior cerebral arteries (PCAs). Either can be very hypoplastic or absent, in which case the remaining, healthier PICA or AICA supplies the entire territory on that side. Once this finding is very relevant, we can hypothesize that the turbulence occurring during the passage of blood flow through such altered vessels can promote the appearance of tinnitus. As we said, the variation may remain compatible with function for a long time, but a minimal constraint may betray its limited flexibility.
Reports in the literature described the use of a modified electronic stethoscope, the auscultear, to assist in evaluating PT (mainly objective tinnitus) [22]. Such data can suggest the possible etiological diagnosis, guiding the use of the most appropriate radiological modalities [12]. However, it cannot detect arteriovenous malformations or arteriovenous fistulas of the dura, which are the most important causes of PT, especially in the presence of normal otoscopic findings [1]. Thus, it should not be used as a screening examination, being indicated only in such limited cases as preoperative evaluation or embolization (or both), evaluation of collateral circulation with possible vessel occlusions, and therapeutic embolizations [3, 5, 7, 8, 12, 13].
When gadolinium contrast enhancement is used, MRI can establish the diagnosis of paraganglioma [6]. It also is extremely useful in evaluating vascular tumors, with special attention to paragangliomas. In this study, MRA was able to detect those causes in 81.25% of patients with PT and normal otoscopy.
Cross-sectional imaging has evolved rapidly and has surpassed the radiography and plain film tomography. One of the most important causes of PT is the paraganglioma, a vascular tumor that appears as a reddish retrotympanic mass. When close to the skull base, such alterations may produce auditory sensation [3, 5] sufficient to disturb an affected patient's life and sometimes may cause serious psychological disorders [2]. Then, other causes of PT must be considered, such as dural malformation, arteriovenous fistulas, intracranial or extracranial aneurysms, a high or dehiscent jugular bulb, and persistent stapedial artery [3, 5, 6, 8-10].

Only three patients presented normal examinations (18.75%), which prevented us from making an etiological diagnosis. Subjective PT is observed only by affected patients, being demonstrable during imaging examinations in only 42% of cases [6].
It may remain compatible with function for a long time, but a minimal constraint may betray its limited flexibility. The most distal segment of the ICVAs forms at a different time embryologically, and often this segment is hypoplastic or even absent. For example, in one patient (DAS; see Table 1) with PT in the right ear and hypoplasia of the right VA, the disorder might be explained, in the absence of other causes, by the turbulent flow in such a narrow vessel.
Until recently, radiological investigation of PT was based on performance of a CT scan associated with arteriography [5, 6].
In our study, all MRI examination results were normal, establishing that it is not a proper examination for evaluating PT, a finding that is consistent with other reports in the literature.
Additionally, it allows the differentiation of vascular neoplasms from those with fewer vascular components, facilitating the differential diagnosis between meningioma and schwan noma. This evaluative technique has had an enormous impact in evaluating patients with PT and normal otoscopic examination, allowing precise etiological diagnosis and adequate treatment of affected patients. However, a normal tympanic membrane mandates differentiating among other diagnoses, such as arteriovenous malformations or fistulas, intracranial or extracranial aneurysms, a high or dehiscent jugular bulb, and persistent stapedial artery. Some examples are paragangliomas, a high jugular bulb, a jugular bulb diverticulum, a pseudoaneurysm, arteriovenous malformations, and stenosis of the transversal sinus [1]. In that case, angiograms show that the ICVA seems to end in the PICAs and that the contralateral ICVA usually is larger and responsible for the major basilar artery supply.
In approximately 10% of individuals, a fetal pattern persists, in which the PCA essentially originates from the ICA and the proximal segment of the PCA from the basilar artery is hypoplastic [21]. The same can be said in relation to another patient (LBK; see Table 1), who had PT and MRA showing dominance of the right PICA and hypoplasia of the left VA.
Currently, arteriography has been restricted to those cases in which MRA is normal, because it may detect small abnormalities not shown in MRA. In 1993, Dietz [6] compared MRI and MRA in the evaluation of 49 patients with PT, noting vascular lesions in 28 patients that were either demonstrated better (46%) or only visualized (36%) with MRA. Owing to the progress of radiological evaluation, magnetic resonance angiography (MRA) has proven to be excellent for evaluating vascular diseases.
In our study, just one patient presented with objective PT, the diagnosis of which was compatible with Arnold-Chiari syndrome (herniation of cerebellar tonsils); the patient showed signs of intracranial hypertension, hydrocephalus, and syringohydromyelia. Thus, its superiority is obvious in precise neurovascular evaluations, demonstrating small vascular alterations, and occasionally in vascular compressions [23]. Presently, this practical, safe, and effective screening method should be used as first choice for these patients, be the tinnitus objective or subjective and accompanied or unaccompanied by retrotympanic mass, cervical lesions, or cranial nerve deficits [11].
From January 1995 to June 1997, the authors prospectively studied 16 patients with PT and normal otoscopic examination. Usually, when the left ICVA is dominant, the basilar artery deviates to the right, whereas it deviates to the left when the right ICVA is dominant.
Middle ear disease can present as ear pain, otorrohea, hearing impairment and other symptoms. All were subjected to MRA evaluation, which revealed the etiological diagnosis in 13 cases (81.25%), including 2 aneurysms and 1 case of intracranial hypertension. Of the 13 patients, 9 (69.23%) presented with at least one variation of vascular anatomy of the skull, showing a close correlation, in most cases, with the side on which PT occurred.
Our results confirm that MRA is an excellent primary screening modality for patients with PT and normal otoscopic findings.
In certain cases, routine and contrast-enhanced Magnetic Resonance Imaging (MRI) scores over HRCT in the evaluation of middle ear soft tissue; however, in most instances, it acts as a next step for confirmation and further characterization.
The authors point out the importance of making etiological diagnoses in such cases, suggesting that variations of the vascular anatomy of the skull are a possible etiology. Features are consistent with cholesteatomaClick here to viewFigure 4 (A, B): Coronal image of the left temporal bone shows soft tissue opacification in the middle ear, sclerosis of mastoid, non-visualization of the ossicles, erosion of the facial nerve canal, tegmen (white arrows in A and B), lateral mastoid wall, and extension into the inner ear (black arrow).
The imaging appearance of facial nerve schwannoma has been described as an enhancing tubular mass (using T1-enhanced MR) within an enlarged facial nerve canal (using CT).
The aberrant carotid artery may be dehiscent or may be covered by cortical bone so that the otoscopic examination can sometimes be normal. A jugular bulb is considered "high riding" if it extends above the level of the floor of the internal auditory canal (IAC).
It is always important to make a note about the extent of the disease, anatomical variants, and possible complications.

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