Disclaimer: The information contained within the Grand Rounds Archive is intended for use by doctors and other health care professionals. These documents were prepared by resident physicians for presentation and discussion at a conference held at Baylor College of Medicine in Houston, Texas. No guarantees are made with respect to accuracy or timeliness of this material. This material should not be used as a basis for treatment decisions, and is not a substitute for professional consultation and/or peer-reviewed medical literature. Osteodystrophies of the Middle Ear and Temporal Bone Five major osteodystrophies that affect the middle ear and temporal bone are presented: Paget's Disease, Osteogenesis Imperfecta, Osteopetrosis, Fibrous Dysplasia, and Osteitis Fibrosa Cystica. The epidemiology, pathophysiology, clinical features, histopathology, diagnosis, treatment and prognosis of these five disorders are discussed. Paget's Disease The classic description of a patient with Paget's disease is that of a deaf old man with a bent back, bowed legs, curved tibia, a large skull and a wobbling gait. However, these advanced changes are not frequently seen. Czerny (1873) was first to describe this disease, but it was Sir James Paget (1877) who correlated and described the clinical and pathological features of this disease. Paget's disease is a chronic, progressive disorder and is believed to be AD or X-linked. The disease primarily affects older people and commonly presents in 6th decade. There is evidence for a viral etiology, possibly a slow virus. Diagnosis is based on history, exam, radiographic and laboratory findings. Frequently, the alkaline phosphatase is often grossly increased; the acid phosphatase is often elevated - prostate cancer should be ruled out. The calcium is usually normal. Demineralization of bone is seen radiographically, such as the well-known osteoporosis circumscripta and cotton-wool patches of the skull. The histology characteristically shows osteoclastic bone resorption and a mosaic pattern of new, lamellar bone interspersed with marrow spaces that become obliterated with fibrous tissue. Typically, pagetoid bone and microfractures are seen in the temporal bone. Symptoms are mainly due to the excess osteoid and resulting soft, easily deformed bones. Hearing loss occurs in 5% - 44%: mixed, CHL or SNHL. CHL component is very rare due to ossicular fixation and surgery is not recommended. Treatment consists of symptomatic relief. Salmon calcitonin can promote healing of osteolytic lesions, and stabilize hearing. Prognosis is generally good; however, there is a 20-fold risk for developing osteosarcoma in the pagetoid lesions and these malignancies are very aggressive lesions and portend a poor prognosis. Osteogenesis Imperfecta Osteogenesis Imperfecta results from a defect in the biosynthesis of the alpha 1 or alpha 2 chains of type I collagen. This results in bone fragility with multiple fractures, bone deformities, thin skin, and capillary fragility with increased bleeding tendency. Histopathologically, those with the most severe form possess thin, immature cortical bone with small, irregular spicules of bone, decreased osteoid matrix and increased fibrous tissue and vascular spaces. A thin, fragile stapes is typical. Those with less severe forms have hypercellular, nonlamellar (immature) bone which fails to mature; there are large remnants of cartilage in the endochondral bone and delay in ossification of the endochondral layer. Radiographically this disorder appears similar to osteoporosis with demineralization / deossification of bone and sometimes with bowing of long bones, thinning of the cortices and exuberant calus formation at fractures. In the skull, embryonic microfusion lines or "wormian bone" is seen. A "halo sign" of demineralization of the otic capsule, similar to otosclerosis, may be found. Previously in two groups (congenita and tarda), they are now grouped in four main categories: 1. blue sclera and an associated CHL; 2. most severe form; 3. blue sclera and an associated CHL, more severe than 1, and associated with skeletal deformities; and, 4. similar to 1, but associated with grey sclera and normal hearing or SNHL. Severe SNHL occurs in 40% of cases and correlates with gray or normal sclera. CHL reflects structural changes in the ossicles and usually correlates with patient with blue sclera. The CHL may be due to soft or missing stapes crural arch, due to otosclerosis or due to a combination of the two. Otosclerosis commonly occurs in association with OI and the histologic independence of these two disorders has been clearly demonstrated. Otosclerosis in these patients tends to be more aggressive and there is a higher incidence of SNHL and window obliteration. Medical treatment with calcium, vitamin D, calcitonin, and anabolic steroids have not been shown to be helpful. Treatment is aimed at function; bracing and orthopedic stabilization is provided as needed, and physical therapy to maintain good range of motion and muscular tone (e.g. swimming) is encouraged. Stapedectomy may yield good results for CHL. Osteopetrosis Osteopetrosis is due to defective osteoclast function with failure of normal bone resorption, while normal osteoblastic bone formation continues with excess deposition of mineralized osteoid and cartilage and displacement of marrow spaces. Radiographically, one sees increased density of all bones with loss of marrow spaces and obliteration of mastoid air cells and paranasal sinuses. Later, the periosteal bone becomes sclerotic without marrow spaces, resulting in dense, brittle bones and anemia. In infants, the temporal bone is primarily dense, calcified cartilage; the stapes exists in fetal form; dehiscence of VII is a consistent finding. Patients with the "tarda" form may be asymptomatic or they may have syndactyly, easy fracturing of bones, bone pain, osteomyelitis, and skull thickening, and, possibly, narrowing of foramina of optic, trigeminal, facial, and auditory cranial nerves. CHL is due to encroachment of bone on the middle ear space with entrapment or ankylosis of the ossicles. Those with the congenital form die at an early age from anemia or sepsis (none live more than 20 years). Bone marrow transplantation from HLA-identical sibs has been used successfully with reversal of anemia & osteosclerosis. Fibrous Dysplasia Fibrous dysplasia usually presents in the 2nd or 3rd decades and is a chronic, slowly progressive, but not self-limiting disease of unknown cause and without a known genetic predisposition. It is pathologically and radiologically similar to osteitis fibrosa cystica. Monostic, polyostic and syndromal (Mc-Cune - Albright) types are described. Histopathology shows replacement of normal cancellous bone by a fibrous stroma arranged in a whorled pattern with "C or Y shapes" of immature, woven bone with scattered islands of cartilage. The marrow is replaced with fibrous tissue. There is active simultaneous osteoblastic and osteoclastic activity. Radiographic studies show thickening +/- sclerosis of bones, especially of the femur, tibia, ribs, jaw and skull; the paranasal sinuses may be obliterated. Variable amounts of the irregularly arranged spicules of bone lead to the "ground glass" appearance on x-ray. The typically unilateral distribution may resemble malignant growth and biopsy may be indicated for confirmation of the diagnosis. Temporal bone involvement is unusual, but it can cause SNHL, vertigo & VII palsy due to erosion. CHL due to EAC stenosis or cholesteatoma can also occur. Major otologic findings include: unilateral CHL; swelling of mastoid or temporal regions; SNHL (erosion otic capsule); stenosis of EAC; cholesteatoma due to stenosis; pain (associated with cholesteatoma); vertigo (erosion otic capsule) or VII paralysis (erosion fallopian canal). Partial surgical removal can be performed for functionally or cosmetically deforming masses. XRT is contraindicated in the treatment of FD because a 0.4% transformation rate to osteo-, chondro-, or fibro-sarcomas (400 time the de novo risk) has been observed. Osteitis Fibrosa Cystica (von Recklinghausen's disease) This disease is due to hyperparathyroidism and the resultant hypercalcemia and loss of bone calcium. Elevated calcium (96% of patient) and elevated radioimmunoassay for iPTH (carboxyl end) provide the diagnosis. The cause is usually a parathyroid adenoma (85-90% cases), occasionally associated with MEN I syndrome. It may also be due to chief cell hyperplasia. (MEN I or Wermer's syndrome consists of hyperparathyroidism, pancreatic islet cell tumors and pituitary tumors.) The hypercalcemia caused by parathryoid hormone influenced release of calcium from bone causes a clinical symptom complex of "Bones, Stones, Moans, Groans, and Hypertones." This refers to the complications of hypercalcimia that are observed: skeletal deformities; muscle weakness and wasting; bone pain and fractures; anemia; renal stones (nephrocalcinosis); abdominal pain, ulcer disease and pancreatitis; and impaired mentation, depression, hyperreflexia, and rarely coma. Histopathology shows tongues of fibrous tissue with leading osteoclasts; the resulting abnormal bone is demineralized and made up of loosely arranged trabeculae of varying sizes interspersed with marrow spaces containing fibrous tissue. Cystic degeneration of fibrous tissue may occur and lead to the formation of brown tumors. Temporal bone shows similar changes and some cases of SNHL have been observed. Radiographic studies show subperiosteal erosions ("pepper-pot skull"), chondrocalcinosis and nephrocalcinosis. Neck exploration are generally curative with restoration of normal calcium balance. Surgery should be entertained especially in those patients that exhibit one of the following five criteria: Ca >11.0, x-ray evidence for metabolic bone disease, presence of a complication of hypercalcemia, active nephrolithiasis, or decreasing renal function. Case Presentation A 72-year-old Hispanic man presented in April 1992 with right hip and back pain. A routine lumbarspine series revealed marked degenerative changes of the lumbar spine with narrowing of the intervertebral spaces and some increased bone densities of the right ilium and lumbar spine. The findings were consistent with degenerative change of the spine or possibly Paget's disease. Further evaluation was significant for an elevated alkaline phosphatase and normal levels of calcium, ionized calcium, phosphorous, magnesium and PSA. A 24-hour urine calcium collection was significantly elevated (416 mg/24 hr). He was seen by the Endocrinology service and started on Indomethacin and Didronel with partial pain relief; salmon calcitonin was then begun with good alleviation of his symptoms. With treatment, his alkaline phosphatase levels decreased to the high normal range. He did well, and in May of 1993 a taper of his calcitonin was commenced. Unfortunately, in November 1993 he re-presented with a compression fracture of L5. He was restarted on calcitonin with good response and subsequently re-tapered off calcitonin over six months. The patient was referred to the Otolaryngology service in September 1994 with a complaint of hearing loss of several years' duration. The loss was greater in the left ear than the right. He also noted mild episodic dizziness over the previous two months. Routine audiometric evaluation revealed a right down-sloping sensorineural hearing loss and a left mixed hearing loss with a significant conductive component. Tympanograms were normal. Laboratory evaluation showed an alkaline phosphatase again elevated (115) and he was restarted on calcitonin with relief of his pain and dizziness. The patient has been referred for amplification and is currently doing well on a tapering dose of calcitonin. Bibliography Andreoli TE, ed. Cecil Essentials of Medicine, 3rd ed. Philadelphia: Saunders, 1993:1415-1468. Armstrong BW. Stapes in patients with osteogenesis imperfecta. Ann Otol Rhinol Laryngol 1984;93:634-636. Berger G, Hawke M, Johnson A, Proops D. Histopathology of the temporal bone in osteogenesis imperfecta congenita - a report of 5 cases. Laryngoscope 1985;95:193-199. Coccia PF, Krivit W, Cervenka J, Clawson C, Kersey JH, Kim TH. Successful bone-marrow transplantation for infantile malignant osteopetrosis. N Engl J Med 1980;302:701-708. Davies DG. Paget's disease of the temporal bone, a clinical and histopathological survey. Acta Otolaryngol Suppl 1968;242:1-47. Edeiken J, Dalinka M, Karasick D. Edeiken's Roentgen Diagnosis of Diseases of the Bone, 4th ed, vol. 2. Baltimore: Williams & Wilkins, 1990. Harersma H. Total decompression of the facial nerve in osteopetrosis. ORL J Otorhinolaryngol Relat Spec 1973;36:21-25. Hawke M, Jahn AF, Bailey D. Osteopetrosis of the temporal bone. Arch Otolaryngol 1981;107:278-282. Khetarpal U, Schuknecht HF. In search of pathologic correlates of hearing loss and vertigo in Paget's disease, a clinical and histopathologic study of 26 temporal bones. Ann Otol Rhinol Laryngol Suppl 1990;145:1-16. Kritzinger EE, Wright BE. Color Atlas of the Eye and Systemic Disease. Chicago: Year Book Medical Publishers, 1984. Lindsay JR, Suga F. Sensorineural deafness due to osteitis fibrosa. Arch Otolaryngol 1976;102:37-42. Marcover RC, Arlen M. Atlas of Bone Pathology with Clinical and Radiographic Correlations. Philadelphia: Lippincott, 1992. Mills BG, Singer FR. Nuclear incisions in Paget's disease of bone. Science 1976;194:201-202. Milroy CM, Michaels L. Temporal bone pathology of adult type osteopetrosis. Arch Otolaryngol Head Neck Surg 1990;116:79-84. Mirra JM. Pathogenesis of Paget's disease based on viral etiology. Clin Orthop 1987;217:162-170. Myers EN, Stool S. The temporal bone in osteopetrosis. Arch Otolaryngol 1969;89:460-469. Nadol JB Jr, Merchant SN. Systemic disease manifestations in the middle ear and temporal bone. In: Cummings, CW, Harker LA, editors. Otolaryngology - Head and Neck Surgery, 2nd ed, vol 4. St Louis: Mosby, 1993:2906-2925. Nager GT. Osteogenesis imperfecta of the temporal bone and its relation to otosclerosis. Ann Otol Rhinol Laryngol 1988;97:585-593. Nager GT, Holliday MJ. Fibrous dysplasia of the temporal bone: update with case reports. Ann Otol Rhinol Laryngol 1983;93:630-633. Parons V. Color Atlas of Bone Disease. Chicago: Year Book Medical Publishers, 1980. Patterson CN, Stone HB 3d. Stapedectomy in van der Hoeve's syndrome. Laryngoscope 1970;80:544-558. Sando I, Myers D, Harada T, Hinojosa R, Myers E. Osteogenesis imperfecta tarda and otosclerosis: a temporal bone histopathology report. Ann Otol Rhinol Laryngol 1981;90:199-203. Schuknecht H. Pathology of the Ear, 2nd ed. Philadelphia: Lea & Febiger, 1993:365-414. Schwartz DT, Alpert M. The malignant transformation of fibrous dysplasia. Am J Med Sci 1964;247:1-. Spranger JW, Langer LO, Wiedemann H-R. Bone Dysplasias: An Atlas of Constitutional Disorders of Skeletal Development. Philadelphia: Saunders, 1974. Suga F, Lindsay JR. Temporal bone histopathology of osteopetrosis. Ann Otol Rhinol Laryngol 1976;85:15-29. 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