British Journal of Radiology (2005) 78, 283-284
© 2005 British Institute of Radiology
doi: 10.1259/bjr/17730869
Whispering enigma
H Ansari, MRCP
1
T Patankar, FRCR
1 and
A Jackson, PhD, FRCR, FRCP
2
1 Department of Radiology, Hope Hospital, Manchester M6 8HD and 2 Imaging Science and Biomedical Engineering, Department of Medicine, Stopford Building, Oxford Road, Manchester M13 9PT, UK
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Introduction
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A 73-year-old lady presented with headaches, dizzy spells and left sided subjective tinnitus. Headaches had been long lasting, intermittent, in the frontal and temporal regions, and dizzy spells were occasional with light-headedness, with no episodes of falls or loss of consciousness. Significant previous medical history included hiatus hernia, irritable bowel disease, trigeminal neuralgia, and spondylosis. Clinical examination was normal with no cerebellar signs. Rinnes and Webers tests were normal. An MR scan (3 Tesla, Achieva; Philips Medical System, Best, Netherlands) was performed to rule out an acoustic neuroma.
What is the radiological abnormality demonstrated in Figure 1
? What are the radiological findings in Figure 2? What is the diagnosis? How would you explain tinnitus on the basis of the imaging findings?
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Figure 1. (a,b) Axial T1 weighted inversion recovery sequence. (c) Sagittal T1 weighted fast field echo.
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The radiological abnormality in Figure 1
is a marked thickening of the diploic spaces, with marked skull softening and descent of the vertex. There is also downward descent of the cerebellar tonsils in the foramen magnum.
The radiological finding in Figure 2 is herniation of the parahippocampal gyrus around the tentorial hiatus, which is causing direct compression of the superior and inferior colliculus on the right side. There is also a smaller herniation on the left causing compression of the superior colliculus.
The diagnosis is Paget's disease.
Compression of the inferior colliculus as a result of the herniation of the parahippocampal gyrus in Paget's disease leads to tinnitus.
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Discussion
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Sound travels from the cochlear hair cells, along the eighth nerve to reach the cochlear nucleus located on the lateral–ventral side of the brain stem under the cerebellum. From the cochlear nucleus, axons stream out mainly along the trapezoid body to join superior olivary nuclei. Axons arising from the superior olivary nuclei join the crossed and uncrossed axons from the cochlear nucleus to form the lateral lemniscus, and eventually synapse in the inferior colliculus on the ventral side of mid-brain just below the thalamus. Most of the cells in the inferior colliculus send their axons to the medial geniculate body of the thalamus in the ipsilateral side of the brain. The cells in the medial geniculate body then send their axons to the ipsilateral primary auditory cortex in the superior temporal gyrus.
Tinnitus is the perception of sound in one or both ears or in the head in the absence of external stimuli. Although the exact physiological causes of tinnitus are not known, a wide variety of ear diseases and disorders including impacted cerumen, acoustic neuroma, Meniere's disease, acoustic over stimulation, open eustachian tube and otosclerosis have been implicated. Medications, most notably aspirin-containing compounds, aminoglycosides and non-steroidal anti-inflammatory drugs may also produce tinnitus.
Tinnitus can be classified in two categories: objective tinnitus, that produced by para-auditory structures, and subjective tinnitus generated by the sensorineural auditory system, subjective tinnitus being much more prevalent than objective tinnitus [1].
Objective tinnitus may be pulsatile or non-pulsatile. Pulsatile tinnitus is attributed to increased turbulence of blood flow, and majority of these cases are attributed to benign intracranial hypertension, atherosclerotic coronary artery disease and glomus tumours.
Subjective tinnitus originates within the auditory system and can be caused by abnormal conditions in the cochlea, the cochlear nerve, the ascending auditory pathway, or the auditory cortex. Functional MRI studies have shown abnormal inferior colliculus activation in lateralized tinnitus patients [2].
Paget's disease of bone, is a disease of unknown aetiology, characterized by excessive and abnormal remodelling of bone. The skull is involved in about two thirds of cases and radiological changes being often advanced by the time of diagnosis. It typically causes enlargement of bone, generalized thickening of vault, middle and outer tables with accentuated trabecular pattern.
Paget's disease complicates the skull in form of basilar invagination owing to softening of bone, malignancy (osteosarcoma and fibrosarcoma) and narrowing of basal foramina, which in turn causes cranial nerve lesion, especially deafness, and occasional compression of medulla oblongata or upper spinal cord. Encroachment on the labyrinthine capsule, distortion of cochlea with osseous fractures between basal and middle turns, and cochlear capsule demineralization have been reported [3].
Tinnitus, vertigo, or both have been reported in about 20% of patients with Paget's disease. Patients with Paget's disease of the temporal bone, are known to have pulsatile tinnitus [4]. In a case review of 165 patients with skull involvement in Paget's disease 31 had tinnitus, 20 of whom had pulsatile tinnitus [5] which some authors attributed to increase in the size and number of the blood vessels and extensive arteriovenous shunting, which is frequently encountered in these cases [6]. The unique feature in our case was the patients clinical presentation with subjective tinnitus, which is unusual and in our opinion is due to inferior collicular compression secondary to her Paget's disease.
Received for publication July 27, 2004.
Revision received December 3, 2004.
Accepted for publication January 5, 2005.
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References
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- Schleuning AJ. Tinnitus. In: Bailey BJ, editor. Head and neck surgery – otolaryngology (2nd edn). Philadelphia, PA: Lippincott – Raven, 1998.
- Melcher JR, Sigalovsky IS, Guinan JJ Jr, Levine RA. Lateralized tinnitus studied with functional magnetic resonance imaging: abnormal inferior colliculus activation. J Neurophysiol 2000;83:1058–72.[Abstract/Free Full Text]
- Phelps PD, Lloyd GA. Diagnostic imaging of the ear (2nd edn). London, UK: Springer-Verlag, 1983:209.
- Sismanis A. Pulsatile tinnitus. A 15-years experience. Am J Otol 1998;19:472–7.[Medline]
- Davies DG. Pagets disease of the temporal bone. Acta Otolaryngol 1968;65(Suppl. 242):1–47.
- Nager GT. Pagets disease of the temporal bone. Ann Otorhinolaryngology 1984;84 Suppl (22):2.
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Introduction
Discussion
