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A 14-Year-Old Young Woman with a Five-Week History of Back Pain

2000; Karger Publishers; Volume: 32; Issue: 2 Linguagem: Inglês

10.1159/000028908

1423-0305

Dachling Pang, Tadanori Tomita, Sharon E. Byrd, James J. Conway, Pauline Chou, Guillermo A. de León,

Infectious Diseases and Tuberculosis

Tadanori Tomita: This is a teenage girl who presented with a 2-week history of midthoracic pain which was also associated at times with epigastric pain. Over the last several days prior to admission, she became unable to stand or to walk, and this was following gradual increase in weakness in her lower extremities. She also noted urinary hesitancy. The pain began in her back approximately 5 weeks ago. It was worse at night and gradually migrated around until it was located in the upper quadrants of her abdomen.The physical examination was a well nourished looking young teenage woman who was in obvious distress. She was alert and oriented. Cranial nerve examination showed that her vision was normal. Extraocular motion was completely normal without nystagmus. The pupils were equal round and reactive to light. Sensation in the face and jaw function were completely normal. Auditory system was normal to speech. The 9th, 10th, 11th and 12th cranial nerves appeared to be normal and intact. Motor examination revealed a 4/5 strength in the lower extremities with equivocal Babinski signs. She had bilateral clonus at the ankles. She had what appeared to be normal rectal tone. The remainder of her examination was without noted abnormality.Preoperative blood work included the following:Complete blood count: white blood cells, 6.9/mm3; red blood cells, 4.28/mm3; hemoglobin, 12.5 g%; hematocrit, 33%; neutrophils, 68%; eosinophils, 1%; basophils, 0%; lymphocytes, 25%; monocytes, 6%; RBC morphology, normal; MCV, 83.1; MCH, 29.1; MCHC, 35.0; RBC dist. width, 14.6; platelet count, 253; mean platelet volume, 9.3. Coagulation studies: PT, 14.0 s; INR, 1.17; PTT, 27.2. Chemistry: sodium, 137; potassium, 3.9; chloride, 106; bicarb., 21; glucose, 95; BUN, 7; creatinine, 0.6; pH, 7.437; PCO2, 30.9; PO2, 305; TCO2, 22; Hb, 11.James J. Conway: X-rays of the entire thoracic spine, AP and lateral, were obtained. Films of the lower and thoracic spine show contrast-filling normal renal collecting systems bilaterally. CT scan showed the lower lumbar vertebrae are grossly normal. Images of the thoracic vertebrae demonstrate collapse of T8 with paraspinal thickening more prominent of the left than the right (fig. 1). The remaining vertebral bodies in the thorax are unremarkable. Films of the cervical spine are grossly normal. There is no fracture or dislocation. The prevertebral soft tissues are normal.Sharon Byrd: An MRI was obtained of the thoracic spine, and this was compared to the previous MRI done 2 days prior at an outside institution (fig. 2). There is total collapse of the vertebral body of T8. The adjacent vertebral body margins of T7 and T9 appear normal. There is marked posterior angulation of the thoracic spine centered at T8. An abnormal signal, most likely representing an abnormal compressive disc, is displaced to the left and right aspects of T8 and posteriorly. The posterior component extends mainly into the right lateral aspect of the thecal sac. There is compression and displacement to the left of the spinal cord at the level of T8. The remaining vertebral bodies throughout the visualized portions of the thoracic spine appear normal in height and signal. Intervertebral discs at all levels of the thoracic spine appear normal. A CT of the thoracic spine at the level of T8 is recommended to better evaluate the bone abnormality.A CT scan with coronal and sagittal reconstructions of the thoracic spine was obtained and compared with the MRI taken at the same date.This CT demonstrated complete compression of the vertebral body of T8, better demonstrated on the current images. The compression vertebral body is abnormal. The vertebral body of T8 contains a lytic expansile mass which demonstrates enhancement after contrast infusion. With contrast, the extent of the vertebral body mass is better demonstrated. The expansile mass extends posteriorly into the spinal canal, causing compression and left posterior displacement of the adjacent spinal cord. There is involvement of the right posterior elements of T8. The mass extends beyond the lateral and anterior borders of the vertebral body of T8. There is extension of the mass into the adjacent right neural foramen. Posterior angulation of the thoracic spine, centered at T8, is again noted.A thoracic spinal angiogram was obtained the same day and compared with the CT and MRI of the thoracic spine. Thoracic aortic angiogram shows good opacification of the aorta and intercostal arteries. A small amount of enhancement is seen extending from the distal portion of the right internal intercostal artery at the level of T8 into the area of the tumor, demonstrated on the previous studies.Selective right intercostal artery angiogram at T7 demonstrates a normal caliber of the intercostal artery with no evidence of stenosis or external compression. No staining is noted.Selective right intercostal artery angiogram at T8 shows increased vascularity and staining in the area of the tumor, demonstrated on previous studies (fig. 3).Selective right intercostal artery angiogram at T9 shows no abnormal vessels and no abnormal stain with contrast. Selective left intercostal artery angiogram at T8 demonstrates no abnormality. No abnormal vessels or stain is noted.Dachling Pang: This case is about a teenage female with a 2-week history of mid-thoracic back pain that radiated to the mid-epigastrium. The pain was worse at night. She then presented with a fairly rapid onset of leg weakness. Her hematological panel, coagulation profile and routine blood chemistry were all normal on admission.The clinical story alone generates a rather extensive list of differential diagnoses, including at least four categories of diseases: infectious/inflammatory, neoplastic, paraneoplastic and vascular. The relatively short duration of back and nerve root pain can certainly be due to bacterial osteomyelitis of the spine, with progression to epidural abscess formation and spinal cord compression. Subacute and chronic vertebral and paravertebral infections also include tuberculosis and various fungal diseases. The absence of predisposing causes and underlying health problems, the lack of systemic symptoms and signs of infection and the normal blood picture make a de novo spinal infection in an otherwise healthy teenager unlikely.Her general good health and normal laboratory tests do not, however, exclude the possibility of a large variety of tumors involving the spine and intraspinal spaces. Tumors typically produce nocturnal pain and progressive compressive symptoms. Primary bone tumors in this age group include giant cell tumors, osteoblastoma, chondroblastoma, osteoid osteoma, chondroma, nonossifying fibroma and osteosarcoma. Except for osteosarcoma, the pain associated with these tumors usually has a long duration measured in months, and signs of cord compression, if any, usually develop very gradually.Many nonprimary tumors of the vertebral column in this age group, however, are malignant and typically have short clinical courses. These are lymphoma, Ewing's sarcoma, rhabdomyosarcoma, other undifferentiated sarcomas, and leukemia and other myeloproliferative diseases. Schwannomas, ependymomas and astrocytomas of the thoracic cord can all cause nocturnal back pain and subtle signs of myelopathy, but again, the duration is usually much longer than 2 weeks, and no superficial stigmata of neurofibromatosis have been associated with this patient.A number of rare lesions not classified as true neoplasms involve the spine. Both eosinophilic granuloma and aneurysmal bone cyst can destroy parts of the vertebra and cause collapse and cord compression.Arteriovenous malformation, arteriovenous fistula and cavernous malformation of the thoracic cord often present with a catastrophic hemorrhage in an otherwise healthy person. A distinct background of antecedent back pain is uncommon, and the neurological deficits are often much more severe than our patient's. Finally, vertebral hemangiomas can cause local bone pain and present with a catastrophic epidural hemorrhage.The imaging studies in this case are what clinch the diagnosis. The sagittal MR shows a complete collapse of the T8 vertebral body with preservation of both adjacent intervertebral discs. In fact, the T8 body seems to have disappeared, qualifying it as a vertebra plana [1]. There is a 30–35° kyphotic deformity of the spine at the T7/T9 junction. No large paravertebral soft tissue masses are seen both anterior and posterior to the bony column, making phlegmonous osteomyelitis, Pott's disease, fungal abscess and infiltrating malignancies unlikely. The intraspinal soft tissue component of this lesion, the part responsible for the extradural cord compression, has a high signal on both the T1- and T2-weighted images, suggesting the presence of extracellular methemoglobin. At least some parts of the soft tissue mass enhanced with gadolinium. The mass to the right of the thecal sac has a cystic center and displays fluid-fluid levels.The axial CT shows that the flattened T8 vertebral body 'spilled over' the rims of the adjacent vertebral bodies and has a ballooned-out shape with thin shells of cortical bone disrupted in places during the collapse. Both pedicles are involved, but the right pedicle and lamina are so affected that only a ghost of the distended cortical shell can be made out. The scan with contrast highlights a soap bubble appearance of the lesion, partly due to enhancement of complex septations within the material core of the lesion. The soft tissue component within the spinal cord again shows cystic compartments with multiple fluid-fluid levels. None of the adjacent vertebrae or the ribs are involved.The MR and CT findings are typical for an aneurysmal bone cyst (ABC) of the spine, complicated by complete collapse of the vertebral body, kyphotic deformity and spinal cord compression. Spinal angiography confirms that the highly vascular lesion is fed by at least two segmental arterial feeders. The contrast travels into widely dilated sinusoidal blood spaces that make up the bulk of the compressive soft tissue mass.ABC is a benign, sometimes rapidly expanding osteolytic lesion consisting of communicating cavities filled with noncoagulated blood [2, 3]. Its exact pathogenesis is unknown, but it is generally thought of as a secondary vascular phenomenon superimposed on an antecedent lesion which presumably initiates a periosteal or intraosseous arteriovenous malformation. The resultant hemodynamic forces generated by the high-pressured vascular channels rapidly erode the bony trabeculae into a cystic cavity. The associated reactive changes within the endosteum and periosteum incite accelerated osteoblastic and osteoclastic activities which then rapidly remodel the bone while conforming to these hemodynamic forces, giving the lesion the ballooned, thin-shelled and multiseptated soap bubble center [4, 5, 6, 7]. The literature is vague about what these 'antecedent lesions' are. In approximately 20–30% of cases, a preexisting neoplasm can be identified [4, 8, 9, 10], the commonest of these being giant cell tumor, followed by osteoblastoma, angioma, chondroblastoma, and more rarely, nonossifying fibroma, chondromyxoid fibroma, fibrous dysplasia and osteosarcoma. Other investigators have suggested that local trauma could be the inciting factor for the formation of some ABCs [7, 11, 12].Serial radiographic and histopathological correlative studies of ABCs identify 4 stages in their natural history that are compatible with the theory of pathogenesis [13, 14, 15]. The initial stage is marked by varying degrees of expansion and thinning of the cortical bone from within, leading to cystic changes; the growth phase is characterized by the expansile, soap-bubbled appearance surrounded by progressively thinning egg-shell cortex; the third and most dangerous phase denotes a sudden explosive increase in size of the blood cysts, causing bony collapse and soft tissue invasion [14, 16]. This usually marks the beginning of rapid neurological deterioration, as in our patient's sudden paraparesis. The final healing phase, only seen in some ABCs, represents spontaneous ossification and shrinkage of the lesion.ABCs make up only 1–1.4% of all primary bone tumors [11, 16, 17, 18]. The mean age at diagnosis varies from 14 to 16 years in several large studies [3, 11, 15]. Rarely is the diagnosis made after 20 years of age. The male to female ratio is 1:1, with a slight preponderance of male patients in some series [3, 11, 19]. More than half of all lesions occur in long bones, always in the metaphysis [5]. The pelvis accounts for about half of all flat bone lesions, and approximately 12–30% of cases occur in the spine [3, 11].The thoracic vertebrae are common sites for spinal ABCs, accounting for about 1/3 of cases [11, 19]. The cervical spine is also commonly affected, probably in another 1/3 cases. Lumbar and sacral lesions make up the last third. In some series, lumbar ABCs are commonest, found in over 45% of cases [3, 20].The posterior elements, in particular the pedicles, are almost universally affected first, but in 60–70% of cases, the lesion extends to involve the vertebral body [3, 5, 11, 15, 19]. It is the continued expansion and destruction of the vertebral body that ultimately leads to sudden collapse, angular deformity and acute compression of the spinal cord, as in this case. In 15–20% of cases, the lesion crosses over to an adjacent vertebra, but never through the intervertebral disc, which always remains normal on imaging studies [3, 11, 21]. The crossover seems to leap around the disc through the surrounding soft tissue, supporting the pathogenetic theory that the periosteal and intraosseous blood vessels, and not the bone itself, are the seat of the underlying pathology.The duration of symptoms prior to diagnosis is usually 4–8 months. The short 2-week course in this case is quite unusual. Local pain is a universal feature for this disease, often worse at night and with recumbency. Neurological symptoms are the next commonest, occurring in 60–70% of cases as the presenting complaint. Early nerve root compression caused the typical radicular, encircling pain in the epigastrium of our patient, and the later myelopathic signs are due to cord compression by the exuberant mass and presumably also by the vertebral collapse and kyphotic changes [3, 11]. Sometimes a tender swelling can be felt over the painful spot, and varying degrees of scoliosis may be secondary to painful muscular spasm or wedge destruction of one half of the body.The imaging findings of our patient are highly representative of a thoracic ABC and have been described in detail. Histologically, ABC has been likened to a blood-filled sponge composed of blood-filled, anastomosing, cavernomatous spaces, separated by septa that are made of fibroblasts, myofibroblasts, osteoclast-like giant cells, osteoid and woven bone [3, 7, 11, 22]. The hypervascularity of the complex septa network accounts for the soap bubble appearance of the core lesion on the enhanced CT and MR. The sedimentation of cellular and proteinaceous elements in the unclotted blood contained inside this multiloculated cyst accounts for the multiple fluid-fluid levels.The standard recommendation is radical excision of all abnormal tissues that feel spongy and bone surfaces that are lined with fragile and hypervascular membranes [1, 3, 11, 15, 19, 20, 23, 24, 25, 26, 27]. Aggressive internal curettage using high-speed cutting burrs is often used to cut back to healthy, well-mineralized bone. The procedure will likely incur significant bone loss with large lesions. Because the posterior elements are always involved, the first attempt should be a midline posterior (in bilateral lesions) or posterolateral (for unilateral lesions) approach. With wide transpedicular resection, the anterolateral aspect of the vertebral body can be exposed from the back, and any anterior extension of disease can be removed this way. If necessary, bilateral transpedicular approaches can be used. In cases where a large amount of abnormal material had spilled forward in front of the vertebra above and below, a second transabdominal or transthoracic approach should be made to finish the resection [25, 26]. Most authors recommend bone grafting in the resection bed, not only to promote healing, but also to buttress the stability of the involved segments.If instability and/or deformity already exists, as in our patient, or if the amount of osseous resection is expected to weaken the stability, then simultaneous instrumentation and fusion should be planned [1, 20, 23, 25, 26, 27]. Posterior instrumentation is most effective and is conveniently performed after posterior resection. If a combined anterior resection is also done, then vertebrectomy, discectomy and autologous tricortical interbody bone grafting should be added, with or without lateral interbody plating.Selective arterial embolization of the arterial feeders has been used preoperatively with moderate success in reducing intraoperative blood loss [13, 18, 28, 29, 30, 31]. Medium-sized particles (250–350 µm) of polyvinyl alcohol are most often used because smaller particles form an almost liquid suspension with the injection medium that has a higher probability of crossing over to feeders of the spinal cord. Embolization is done on an awake patient who is first given a provocative dose of sodium amytal into the arterial feeders intended for occlusion, to rule out the possibility of 'functional sharing'. If no neurological deficit is elicited, the polyvinyl alcohol particles are injected under real-time somatosensory evoked potentials monitoring [18]. The operation should be done no more than 2–3 days after embolization, before collaterization of new blood supply takes place [13]. Detachable thrombogenic coils are not used to occlude the parent artery to allow for reembolization in case of recurrence of the lesion [13, 18].Embolization has also been used as the primary modality of treatment in special circumstances, such as for: (1) recurrences after multiple surgical extirpations; (2) lesions in hard-to-reach places such as parts of the ilium and sacrum, and (3) to stop progression of disease in spinal lesions before collapse occurs so as to avoid the need for mutilating surgery and iatrogenic destabilization [18]. Pain reduction, neurological recovery, shrinkage of mass and reossification of the bone cyst have been observed 3 months to 2 years after embolization [11, 18, 29, 30]. Presumably, the occlusion of arterial feeders dampens the hemodynamic forces that underlie the destructive remodeling of the osseous matrix and promotes spontaneous reossification. A similar mechanism probably explains the spontaneous healing of some ABCs that have undergone limited curettage or simple needle biopsy [3].Occasionally, no arterial feeders are identifiable for embolization. Direct percutaneous injection of the cyst with sclerosing solution has been used to induce involution of the lesion. Gulbaud et al. [32]used an alcoholic solution of corn protein (alcoholic zein) that induces intravascular thrombosis, marked local inflammation and an ensuing fibrogenic reaction that triggers the reparative process of mineralization and bone reconstruction. They reported complete improvement of 87% of cases and partial healing in 13% with a 5% incidence of serious complications.When referring to ABCs, the term recurrence ought to be properly defined as continued progression of disease left behind by incomplete treatment, rather than regrowth of lesions as in the context of neoplasia. Incomplete excision of ABC carries a 50–60% rate of disease progression. Even with aggressive resection, the recurrence rate is 10–20%. Ninety percent of the recurrence occurs within 6 months of therapy. The only proof of cure is shrinking of the lesion mass and reossification of the cystic areas.For this patient, I recommend preoperative embolization of the identifiable arterial feeders, followed by a midline wide posterior exposure and bilateral transpedicular resection of the lesion. It is very possible removal of the large intraspinal and pedicular masses might open access to the anterior extension of the lesion and what remains of the T8 vertebral body, permitting discectomy and insertion of an interbody bone graft. If so, posterior instrumentation and correction of the kyphotic deformity can be accomplished. If exposure to the bodies is inadequate from the back, then a separate transthoracic approach should be used, either in the same sitting or at a later date.Clinical diagnosis: aneurysmal bone cystPauline Chou, Guillermo A. de Leon: Small hemorrhagic fragments of bone and soft tissue were received for examination. Microscopically, pieces of markedly disrupted or degenerated cancellous bone were intermixed with proliferated fibrous tissue and with nests of multinucleate giant cells (fig. 4). In some places, the bone was reduced to a thin shell covered with periosteum; however, fibrosis and inflammation did not seem to spread into the latter. Fresh hemorrhages, clusters of hemosiderin-laden macrophages and proliferated thin-walled blood vessels were prominent within the dilated and often honeycombed or empty-looking bone marrow spaces (fig. 5).Pathological diagnosis: aneurysmal bone cystTadanori Tomita: Because of the progressive myelopathy due to the ventral mass lesion in the spinal canal, surgical resection of this lesion through posterior anterior thoracotomy of the right side was elected. Prior to surgical intervention, the patient also had spinal angiography which showed minimal to mild vascularity from the intercostal artery of T7.A posterolateral thoracotomy with resection of the rib of T7 was performed followed by an extrapleural approach to the crushed T7 vertebral body.The diseased pedicle of T7 and the facet were removed. A cystic lesion was noted on the right side lamina which was also removed. The ventral spinal canal was occluded by a cystic mass lesion. Further, crossing the midline, the vertebral body was noted to have undergone cystic change, and this was removed for the pathological investigation.The left side epidural space also had a cystic mass which was removed by enlarging the space by removing the cystic mass from the vertebral body. Further debulking was undertaken, and the above and below disc spaces were identified and properly preserved.The anterior spinal fusion using fragmented autologous rib bone graft was done. When the procedure was terminated, the epidural space was nicely compressed.