Volume 1, Issue 2 , Pages 138-141, June 2006
Dizziness as presenting symptom of monostotic fibrous dysplasia
Article Outline
Summary
Fibrous dysplasia is a rare, benign disease even though clinical picture may assume severe aspects. It presents a progressive replacement of normal bone structures by fibrous tissue which can involve one or more bone segments and, in some cases, it could be associated with skin lesions and endocrinopathies (McCune–Albright syndrome). It manifests clinically with dysmorphic syndrome, ophtalmologic or otologic signs. Vertigo in an uncommon presentation symptom. We report a case of monostotic fibrous dysplasia of the temporal bone presenting as dizziness in an 11-year-old boy and review the scientific literature.
Keywords: Fibrous dysplasia, Dizziness
1. Introduction
Fibrous dysplasia (FD) was first described by von Reclinghausen [1]. It presents a progressive replacement of normal bone structures by fibrous tissue. It can be classified as [2]:
Some authors consider monostotic and polyostotic forms as different diseases. The ongoing of disease is slightly progressive and arises in childhood or in the young adult [3].
Several theories have been advanced to explain the etiology of FD. They theorize a congenital anomaly of the mesenchyma bone forming portion, anomalies in the normal bone repair process and sequestration of maturing bone [4]. The common issue of all benign fibro-osseus lesions of the craniofacial region is the replacement of normal bone by benign cellular fibrous tissue containing different amounts of mineralized material [5].
These conditions are often associated with hearing loss and could present different degrees of skeletal and audiological involvement. Hearing loss is conductive at the early stage of disease while later it tends to become sensorineural [6].
No previous reports refer dizziness as presenting symptom. We describe a case report of monostotic fibrous dysplasia of the temporal bone occurring in an 11-year-old boy and aroused with peripheral labirinthic hyporeflectivity.
2. Case report
A 11-year-old boy presented at the ENT department of children's Hospital “Burlo Garofolo” Trieste complaining dizziness. Two days before, after a somersault, he felt right aural fullness lasting 12
h. Forty-eight hours later, vertigo arose without audiological symptoms. At the presentation, the patient showed a marked fall to the right, worsened by the eyes closed. An horizontal left beating nystagmus was present. Nausea and vomiting occurred in the next 2h. Physical examination showed a mild narrowing of the right external ear canal, no visible or palpable abnormalities of the skull. Pure tone audiometry and admittance test were normal. Auditory Brainstem Response (ABR) confirmed the presence of waves I, III and V with normal waveform morphology, peak latency and inter wave latency. Laboratory tests shows no abnormal values. Abnormal skin pigmentation was not present. Two weeks later, an electronystagmographic recording with bithermal caloric test was performed. Right labirinthic weakness was present. Computed Tomography (CT) scans showed alteration of the trabecular component of right temporal bone associated with a wide cystic lesion. No abnormalities were evident in middle and inner ear structures (Fig. 1, Fig. 2). Magnetic Resonance Imaging (MRI) showed no compression of pontocerebellar structures (Fig. 3). A full remission of symptoms was obtained with steroid therapy (Predinison 1mg/kg/die for 2 days). Total body radiographic examination did not reveal any polyostotic involvement.
Fig. 1.
3D CT scans: wide involving of the temporal bone.
Fig. 2.
Coronal CT scans of temporal bone showing the narrowing of internal auditory canal.
Fig. 3.
RMN of the inner ear reveals a cystic lesion involving the lateral semicircular canal.
3. Discussion
Fibrous dysplasia involves craniofacial structures in a different percentage depending on the severity of the disease. In fact, it affects them in 10% of the monostotic, in 50% of the mild polyostotic and in 100% of severe polyostotic forms, interesting prevantly the upper maxilla and the mandible. In the polyostotic forms, locations of disease could be limited to one limb, to one hemibody or have a wider diffusions with bilateral forms [7]. Temporal bones present fibrotic area in only 18% of cases [2].
The external auditory canal is involved in 80% of cases and it results in a progressive stenosis of the canal lumen, a secondary conductive hearing loss and a cholestatoma following keratin entrapment [8]. In most cases, the anatomical changes produce unaesthetic asymmetry. The middle ear involvement is consequent to the external auditory canal stenosis. Therefore, we could observe chronic otitis media, with or without cholesteatoma, and ossicles destruction, labyrinthitis, sensorineural hearing loss and facial palsy [9]. Some cases with the involvement of the otic capsule have been reported [5], [7], [9]. They usually present fibrous dysplasia affecting cochlea and labyrinth, causing sensorineural hearing loss due to the cochlear destruction, narrowing of the inner auditory canal or vestibular fistula. No previous reports indicate the involvement of the vestibular system. The slow progression of disease could be responsible for the lack of dizziness before hospitalisation of our young patient. In addiction, narrowing of the internal auditory canal was present. Central nervous system plasticity can compensate unilateral hyporeflectivity determined by the remodelling of the otic capsule. Opthalmologic signs could be present when the disease affects the ophtalmic nerve [7].
Laboratory studies should include evaluation of serum calcium, phosphorus, and alkaline phosphatase levels, even though normal levels are present in most patients [3].
Computer tomography represents the optimum in showing changes in the temporal bones. So we can distinguish three principal features [6]:
Magnetic Resonance is an useful tool in the evaluation of soft tissue and fibrous components, and in assessing the relationship with other structures of the skull base as well as jugular vein and brain stem. It represent a safe non-invasive test in the follow-up of the patient [10]. Scintillography with Tc99 and Ga67 is an imaging technique that detects and identifies polyostotic locations of FD [11].
Differential diagnosis should be performed with more common diseases. It includes bone aneurysmatic cyst, Paget's disease, osteochondroma, osteoma, sclerosing bone disease. The presence of a laminar bone tissue and a fibrous matrix is pathognomonic for fibrous dysplasia.
The use of corticoids is helpful in the management of pain. Surgery is the best choice in reestablishment of hearing and to prevent the arising of cholesteatoma, while a “wait and see” management could be indicated only in the asyntomatic patients. Barrionuevo et al. suggest canaloplasty and placement of a stent in these patients [5]. The recurrence of the disease is high and patients should know it. Malignant evolution of disease may occur [12]. Periodic follow-up includes CT scans to evaluate the ongoing of the disease and the presence of any complication.
4. Conclusion
Fibrous dysplasia is an uncommon disease characterized by progressive normal bone tissue replacement by fibrous tissue elements. The temporal bone is involved in various degrees, the most common of which is stenosis of the eternal ear canal. Dizziness represents a very low incidence symptom. Nonetheless, fibrous dysplasia should be suspected in children with dizziness presenting asymmetric narrowing of the outer ear canal. Treatment is conservative and reserved to restore hearing and eliminate any aesthetic deformity. Evolution is unpredictable.
References
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PII: S1871-4048(06)00041-4
doi:10.1016/j.pedex.2006.03.003
© 2006 Elsevier Ireland Ltd. All rights reserved.
Volume 1, Issue 2 , Pages 138-141, June 2006
