Spinal manifestations of skeletal dysplasias.

Skeletal dysplasias, disorders of abnormal bone and cartilage development, are a heterogeneous group, each disorder with its own genetics, prevalence, prognosis, and treatment. More than 150 distinct conditions have been identified. Despite their obvious differences, the osteochondrodysplasias share many clinical and radiographic features. These patients present to the orthopedic surgeon for evaluation of disproportionate short stature, which may be apparent at birth or manifest itself only with further growth. This article discusses bone dysplasias commonly associated with spinal abnormalities. Spinal pathology can lead to deformity, neurologic sequelae, pain, and cardiopulmonary compromise and further contribute to short stature.

Computed tomography-guided biopsy of the spine. A review of 103 patients.

STUDY DESIGN: A retrospective study of 103 computed tomography-guided biopsies of the spine. These represent a consecutive series of patients with spinal lesions or disorders observed over a 32-month period. OBJECTIVES: To determine the diagnostic accuracy and clinical usefulness of computed tomography-guided biopsies with respect to major influencing variables. SUMMARY OF BACKGROUND DATA: Computer tomographic-guided biopsy of the spine is considered a safe, accurate, and relatively inexpensive examination technique. A study comparing its diagnostic accuracy with respect to all the variables of age, gender, radiographic appearance, spinal level, tissue type, or pathologic diagnosis has not been done. METHODS: Biopsy specimens were sent for cytologic and histologic analysis. Bacteriologic studies were performed when clinically indicated. The biopsy results were analyzed for adequacy and diagnostic accuracy, i.e., the ability to generate a tissue sample adequate for pathologic examination and one that yields diagnostic information. RESULTS: The mean age of patients was 60 years, with a range of 4-91 years. The spines of 52 males and 51 females were studied. There were eight cervical, 28 thoracic, 53 lumbar, and 14 sacral lesions used as biopsy sites. The radiographic appearance of spinal lesions were lytic in 74 cases, blastic in four cases, and mixed in two cases. Tissues undergoing biopsy included bone (63 cases), soft tissue (35 cases), and mixed specimens (five cases). The pathologic examinations revealed 18 infections, 23 primary neoplasms, 34 metastases, and 19 normal tissues. An adequate specimen for pathologic examination was obtained in 90 biopsies (87%). A diagnosis was achieved in 67 of 94 patients (71%). Diagnostic rates obtained in thoracic level biopsies were lower than those from biopsies of other spinal levels (P = .007). CONCLUSION: Computed tomography-guided biopsy is an important tool in the evaluation of spinal lesions. A positive biopsy result may preclude the need for open surgical intervention. This study included one of the largest series of patients in the medical literature. In addition, it determined the diagnostic rates of this procedure with respect to the major influencing variables. Thoracic-level biopsies have a diagnostic rate that is significantly lower than that of other spinal levels. No significant correlation was found between diagnostic accuracy and age, gender, radiographic appearance, tissue type, or eventual diagnosis.

Loudness perception and frequency discrimination in subjects with steeply sloping hearing loss: possible correlates of neural plasticity.

Loudness functions and frequency difference limens (DLFs) were measured in five subjects with steeply sloping high-frequency sensorineural hearing loss. The stimuli were pulsed pure tones encompassing a range of frequencies. Loudness data were obtained using a 2AFC matching procedure with a 500-Hz reference presented at a number of levels. DLFs were measured using a 3AFC procedure with intensities randomized within 6 dB around an equal-loudness level. Results showed significantly shallower loudness functions near the cutoff frequency of the loss than at a lower frequency, where hearing thresholds were near normal. DLFs were elevated, on average, relative to DLFs measured using the same procedure in five normally hearing subjects, but showed a local reduction near the cutoff frequency in most subjects with high-frequency loss. The loudness data are generally consistent with recent models that describe loudness perception in terms of peripheral excitation patterns that are presumably restricted by a steeply sloping hearing loss. However, the DLF data are interpreted with reference to animal experiments that have shown reorganization in the auditory cortex following the introduction of restricted cochlear lesions. Such reorganization results in an increase in the spatial representation of lesion-edge frequencies, and is comparable with the functional reorganization observed in animals following frequency-discrimination training. It is suggested that similar effects may occur in humans with steeply sloping high-frequency hearing loss, and therefore, the local reduction in DLFs in our data may reflect neural plasticity.