Paget's disease, also known as deforming osteitis, is a localized chronic disorder that occurs when the body loses control over the normal process of bone remodeling, and is characterized by excessive bone resorption followed by overproduction of new bone(1,2). It may be related to infection by paramyxovirus (1) , but its etiology remains unclear (4,5). An autossomal dominant pattern of inheritance has been disclosed (5), predominantly in 40-year-old and over Caucasian males (M:F 1,5:1) (5,6,7). Patients are asymptomatic in most cases; however, Paget's disease may be accounted for axial bone chronic pain, joint pain, skeleton deformities, hearing loss, and compression of cranial nerves (4). Expansion of cranial bones affecting temporal bones may lead to hearing loss because of inner ear lesion (6). Most often Paget's disease is discovered incidentally, when radiographs or lab tests are requested for other reasons. Its diagnosis is made by signs and symptoms, physical examination, imaging procedures and levels of bone metabolism markers, mainly seric alkaline phosphatase (6). Hearing loss occurs in about 50% of the cases, and it occurs due to alterations in bone density, shape and mass, which altogether contribute to the delicate harmony of synchronized movements between the middle and inner ear (8). Symptoms like vertigo and tinnitus can also be seen (1, 7, 8, 9).
Type 1 Chiari malformation is a rare disorder, most seen in adults, and is a cause of vertigo of central origin. It occurs when cerebellar tonsils slide through the foramen magnum into the cervical canal (10, 11). Most commons symptoms are pain, asthenia and headache, and these are often preceded by otoneurologic manifestations. Sensorineural dysacusis, vertigo, nystagmus, ataxia, tinnitus, and other cranial nerve disorders have been reported with this condition (10, 12, 13). Audiologic tests and imaging procedures, especially magnetic resonance imaging (MRI), are of extreme importance because they display alterations in the cerebellopontine angle region (12). The otolaryngologist and the neurologist must understand and recognize type 1 Chiari malformation as part of the differential diagnosis of balance disorders, because this may be the initial manifestation of this disease (13).
We report a case of Paget's disease evolving to type 1 Chiari malformation , its course and prognosis.CASE REPORT
A 57-year-old Brazilian caucasian male, who worked as a cabinet-maker, came to our otolaryngology outpatient service complaining of tinnitus and bilateral hearing deficit for six years, vertigo and loss of balance for about two years. Personal history disclosed diabetes mellitus (DM) and systemic hypertension (SAH), treated with diet, glibenclamide and hydroclorotiazide.
His father died after progression of symptoms similar to his without final diagnosis. This patient had been requested an otoneurologic evaluation by his neurologist and his orthopedist. At initial examination, oroscopy, rinoscopy, and otoscopy were normal. There was no Romberg sign. There was a right-beating nystagmus present at oblique dislocation of the head. Apendicular coordination was normal. There were no signs suggestive of syringomielia or hydrocephalus.
Head CT scan demonstrated thickening of the skull vault (Figure 1). Electroencephalogram with no evidence of focal activity.
Figure 1. Head CT scan demonstrating focal thickening of the cranial vault.
Audiometry demonstrated bilateral mixed dysacusis, 40 dB gap in the right ear and 20 dB in the left ear, with sensorineural hearing decay from 2 kHz in both ear.
Imitanciometry demonstrated normal tympanic membranes and bilateral absence of stapedian reflexes.
Otoneurologic examination disclosed right-sided deficitary peripheral vestibular syndrome.
Auditory brain stem response demonstrated ill-defined waves in right ear; in left ear, the exam disclosed ill-defined wave I, with prolonged waves III and V latencies. This exam did not rule out retrocochlear disease.
Temporal bones and head MRI disclosed thickened cranial vault with diffuse heterogeneous signal and gross bone trabeculae, suggestive of Paget's disease and signs suggestive of type 1 Chiari malformation (Figure 2).
Figure 2. Brain MRI demonstrating sliding of the cerebellar tonsils through foramen magnum, corresponding to Chiari type I malformation.
Seric calcium 9.3 mg/dl (normal range 8.5 - 10.5 mg/dl), urine hydroxiproline 531 UI (normal range 100 UI - 300 UI), seric alkaline phosphatase 2100 UI/l (normal range 110 UI - 360 UI/l).
During the diagnostic workup the patient was on bromazepam by the neurologist, non-steroidal anti-inflammatories (NSAI) by the orthopedist, medications for vertigo, papaverine, quinine and vitamin A for the otoneurologic symptoms, without any improvement, but in the next 5 months, there was worsening of the headache, pain in the legs, widening of the base of support, ataxic gait, and dysphagia.
The diagnosis of Paget's disease evolving to type 1 Chari malformation was made, and the patient was referred back to the neurologist and to an endocrinologist, and conservative treatment was instituted with sodium alendronate, calcium carbonate, amitryptiline, NSAI and analgesics, with improvement of the symptoms. DISCUSSION
Paget's disease evolving to type 1 Chiari malformation is rarely described in medical literature, and only three case reports have been published so far (13, 14, 15). In the case reported here, we present a 57-year-old male patient who fulfilled the criteria to Paget's disease. In relation to the otoneurological symptoms found in this disorder, mixed hearing loss is commonly seen because the temporal bone is afflicted (8). This patient had, besides mixed hearing loss, tinnitus and vertigo, two other symptoms similarly found in Paget's disease (1,9,10).
Type 1 Chiari malformation occurred because of thickening of the cranial vault due to the bone disorder, and compression of the encephalic structures ensued, forcing the sliding of cerebellopontine structures through the foramen magnum inside the spinal canal. So, besides symptoms frequently seen in type 1 Chiari malformation patients, like neurosensorial dysacusis, vertigo, nystagmus and tinnitus (12,14,15), this patient also presented with gait ataxia, dysbasia and dysphagia, the latter due to bulbopontine compression.
In the initial workup, head CT scan already demonstrated disease of the cranial vault, with important thickening. The audiometric abnormalities demanded further evaluation with more complex imaging procedures. Magnetic resonance imaging (MRI) would be the procedure of choice facing a central vestibular disorder because of brain parenchyma or cochleovestibular system disorders (7), and head MRI was ordered, disclosing vertebrobasilar invagination and signs suggestive of Paget's disease. From this point, bone metabolism markers were ordered, confirming the diagnosis of Paget's disease, with significant raise of seric levels of alkaline phosphatase and urine levels of hydroxiproline. In most Paget's disease cases, seric levels of calcium remain in the normal range (2), as was observed here.
Because of a past personal history of DM and SAH, and in view of Paget's disease with advanced biochemical activity, surgical treatment was not considered, and clinical conservative treatment was the option chosen, with satisfactory control of the otoneurological manifestations and the other symptoms presented by the patient. Conservative treatment was also instituted for other cases presented in literature (13, 14, 15).FINAL REMARKS
This case illustrates the need to use a differential diagnosis approach in front of a patient presenting with otoneurological manifestations, warning the otolaryngologist and the neurologist to look for less common disorders. With a differential diagnosis in mind, the case can be conducted more satisfactorily towards and adequate and effective treatment, with improvement of the prognosis.
Acknowledgements: The authors would like to thank the Hospital Nossa Senhora de Lourdes for its support in the preparation of this manuscript. The authors have no competing interests to declare. No grants of any kind were received by neither of the authors. This manuscript was approved by the ethics committee of the Hospital Nossa Senhora de Lourdes.REFERENCES
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1. Médica (Residente do Serviço do Otorrinolaringologia do Hospital Nossa Senhora de Lourdes - São Paulo-SP)
2. Médico (Chefe do Serviço do Otorrinolaringologia do Hospital Nossa Senhora de Lourdes - São Paulo-SP)
3. Médico (Neurologista do Hospital do Servidor Público Estadual - São Paulo - SP)
Serviço de Otorrinolaringologia do Hospital Nossa Senhora de Lourdes - São Paulo-SP
Rua das Perobas, 295/344 04321-120 - São Paulo-SP
Este artigo foi submetido no SGP (Sistema de Gestão de Publicações) da RAIO em 18/1/2006 e aprovado em 12/5/2006 15:08:31.