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Abstract
This study aimed to evaluate the scope of imaging findings seen with both CT and MRI in patients with tinnitus, and to asses when to use CT or MRI, and when to use both modalities together.
During the period from August 2005 to June 2006, 31 patients (14 males and 17 females) complaining of tinnitus were evaluated by history taking, clinical examination, CT and MRI.
NECT showed well defined CPA masses associated with widening of the IAC in 10 cases of acoustic neuroma, it was unilateral in 9 cases and bilateral in one case of neurofibromatosis type II. 7 cases showed homogenous post contrast enhancement ,while 2 cases showed heterogenous enhancement as they were large in size they showed central areas of degeneration.
MRI was done in 2 cases of this group, it showed an excellent delineation of the intracanalicular extension in the IAC, the vestibular and cochlear divisions of the eighth cranial nerve in these two cases, it showed the same contrast enhancement pattern as CT.
NECT showed unilateral well defined hyperdense CPA masses in 3 cases of meningioma , it was unilateral in 2 cases and bilateral in one case associated with bone sclerosis of the temporal part of the petrous bone in one case, and erosion of it with the clivus in the other case denoting sarcomatous changes in the mass. They all showed homogenous post contrast enhancement. MRI was done to the 3 cases , it showed the exact site and size of the masses in the 2 cases, and showed multiple masses in the third case that was not well detected by CT.MRI showed homogenous post contrast enhancement and enhanced dural tail in the 3 cases
NECT of the temporal bone, showed the enlargement and erosion of the jugular foramen, and clivus in one patient with glomus jugular tumor, However MRI showed the exact site of the mass and its relation to the jugular fossa, post contrast CT and MRI showed the characteristic pattern of enhancement of the mass
In the 2 cases of squamous cell carcinoma CT showed soft tissue mass seen in the external and middle ear cavities with extensive bone erosion of both of them ,and of the ossicles . The second case showed more aggressive bone erosion extending to the infra temporal fossa, petrous apex, jugular fossa and the occipital condyle. Post contrast CT showed heterogenous pattern of enhancement in both cases.
NECT showed a soft tissue mass in the middle ear cavity, with ossicular erosion and loss of mastoid areation in 7 cases of cholesteatoma .The mastoid air cells were filled with soft tissue density lesion in 2 cases of mastoid abscess associated with a sinus tract in the temporal bone in one case.
NECT showed enlarged right jugular fossa associated with high right jugular bulb in one case , with intact bony plate between the jugular vein and the carotid artery.
CT in bone algorithm it showed bilateral fracture lines in temporal bone in one case of trauma ,a transverse fracture line on the left side with bone fragments, and longitudinal fracture line on the right side .
CT in 3 cases was normal with no radiological abnormalities to explain their tinnitus.
In one case with idiopathic intracranial hypertension the diagnosis was suspected clinically and confirmed by lumbar puncture
In one case of systemic hypertension and treated with calcium channel blocker. The diagnosis was by history taking and confirmed by cessation of the tinnitus after the patient had stopped the medication for a while.
In one case he was diagnosed as Minere’s disease in ENT department.
Conclusion
Tinnitus is a symptom often causing a diagnostic dilemma. It may be caused be a wide variety of causes including normal vascular variants, temporal bone and CPA tumors, inflammation of the middle ear, fractures, idiopathic intracranial hypertension, or any other systemic cause.
Every effort must be done to diagnose the cause and exclude potentially life threatening causes.
Radiological examination is a cornerstone in the diagnostic work up. History and clinical examination are very important before radiological examination.
Direct communication with the referring clinician is essential. In the presence of tinnitus with any other symptoms of increased intracranial tension like vomiting, headache, blurring of vision, CT with contrast is recommended to rule out tumors as the cause of tinnitus.
In the presence of tinnitus with ear discharge, pus ,blood, Non contrast CT is recommended to rule out cholesteatoma as the cause of tinnitus.
If the tinnitus was pulsatile with no any other associated symptoms, vascular causes had to be excluded by CT.
If no abnormalities were detected by these procedures, the probability of significant diseases became minimal.
CT was good in delination of site of the CPA masses ,presence of calcifications ,glomus juglare tumor and squamous cell carcinoma ,and in detection of the state of the bone surrounding them. CT was excellent in detection of mastoid aeration, middle and external ear cavities aeration ,ossicular state either eroded or dislocated, CT was excellent in detection of the level high jugular bulb ,the bone state surrounding either intact or eroded. CT was excellent in detection of the extension of the fractures line.
MRI was better in delinning the site and the exact size of the CPA masses and detection of the small masses that were not well seen by CT.