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PubMed2006

Optimal wavelets for biomedical signal compression.

Signal compression is gaining importance in biomedical engineering due to the potential applications in telemedicine. In this work, we propose a novel scheme of signal compression based on signal-dependent wavelets. To adapt the mother wavelet to the signal for the purpose of compression, it is necessary to define (1) a family of wavelets that depend on a set of parameters and (2) a quality criterion for wavelet selection (i.e., wavelet parameter optimization). We propose the use of an unconstrained parameterization of the wavelet for wavelet optimization. A natural performance criterion for compression is the minimization of the signal distortion rate given the desired compression rate. For coding the wavelet coefficients, we adopted the embedded zerotree wavelet coding algorithm, although any coding scheme may be used with the proposed wavelet optimization. As a representative example of application, the coding/encoding scheme was applied to surface electromyographic signals recorded from ten subjects. The distortion rate strongly depended on the mother wavelet (for example, for 50% compression rate, optimal wavelet, mean+/-SD, 5.46+/-1.01%; worst wavelet 12.76+/-2.73%). Thus, optimization significantly improved performance with respect to previous approaches based on classic wavelets. The algorithm can be applied to any signal type since the optimal wavelet is selected on a signal-by-signal basis. Examples of application to ECG and EEG signals are also reported.

Algorithms↗

PubMed1986

Acute changes in somatosensory evoked potentials following graded experimental spinal cord compression.

Amplitude and latency of cortical somatosensory potentials evoked in cats by peripheral nerve stimulation were measured before, during, and for 5 hours after injury of spinal cord segment L-7 by a predetermined degree and duration of compression. An amplitude decrease, slight and transitory, was first observed after compression reduced the segmental cross section by 60%. After an 80% compression, amplitude reduction was initially larger and lasted longer, but recovered 2.5 hours after injury to a level that did not differ statistically from control values. After total (100%) compression, evoked responses disappeared abruptly and did not recover significantly. Latency was unaltered at all degrees of compression. Structural damage increased with the degree of compression. In this model, evoked potential changes neither reflect nor predict the magnitude of acute incomplete spinal cord injury.

Animals↗

PubMed2006

Physical properties of root cementum: part 7. Extent of root resorption under areas of compression and tension.

INTRODUCTION: The aim of this article was to quantify the extent of root resorption in areas of compression or tension under light and heavy buccal tipping orthodontic forces. METHODS: The sample consisted of 36 premolars in 16 patients. On 1 side, light (25 g) or heavy (225 g) buccal tipping orthodontic forces were activated for 28 days. The contralateral side in each patient served as the control (0 g). The teeth were extracted, disinfected, imaged under a scanning electron microscope, and analyzed with commercial stereo imaging computer software modified for this study. Buccal and lingual surfaces were divided into 3 equal regions: cervical, middle, and apical. The root surface areas of these regions were documented with straight-on images. Quantification of resorption craters by using volumetric analysis was performed from stereo images taken at +/-3 degrees. The degree of resorption was correlated to the amount of surface area under compression or tension. RESULTS AND CONCLUSIONS: The buccal cervical region had 8.16-fold more root resorption in the heavy-force group compared with the light-force group (P <.01). The other regions did not seem to have significant differences in the force levels. In the experimental teeth, there was more root resorption in the high-compression regions than in the other regions (P <.01). There were similar amounts of resorption per unit area on the lingual apical and buccal cervical regions. Regions under compression had more root resorption than regions under tension. There was more resorption in regions under heavy compression than in regions under light compression (P <.01). There was also more root resorption in regions under heavy tension than in regions under light tension (P <.01).

Adolescent↗

PubMed2006

Mechanical compressive loading stimulates the activity of proximal region of human COL2A1 gene promoter in transfected chondrocytes.

Previous studies have demonstrated that the mechanical compressive loading affects the biosynthesis of chondrocytes seeded in three dimensional scaffolds. In this study, the level of type II collagen mRNA expression was increased by a continuous dynamic compression at 10% compressive strain and 0.1 Hz in chondrocytes seeded in a biodegradable, elastomeric scaffold, poly(L-lactide-co-epsilon-caprolactone) (PLCL). To further examine this molecular mechanism, the promoter region of COL2A1 gene, which is encoding type II collagen, was analyzed using rabbit chondrocytes transfected with luciferase reporter vectors containing the 5'-flanking regions of human COL2A1 gene. A deletion mutant analysis revealed that the most active short promoter in response to continuous dynamic compression is in the region between -509 and -109 base pairs, where the transcription factor Sp1 is located. Additionally, an mRNA decay experiment using transcription inhibitor actinomycin D demonstrated that dynamic compression do not stabilize type II collagen mRNA. Our results indicate that mechanical compression increases the level of type II mRNA expression by transcriptional activation possibly through the Sp1 binding sites residing in the proximal region of the COL2A1 gene promoter.

Animals↗

PubMed2005

Effect of intermittent compression therapy on bone mineral density in women with low bone mass.

Intermittent pneumatic compression has been shown to increase blood flow in the leg which, in turn, may improve BMD. We performed a pilot study to assess whether intermittent compression of the leg could improve BMD at the femoral neck. 37 postmenopausal women with low bone density T score < -1 at either hip or spine were recruited into the study of whom 24 completed. Women applied intermittent compression for 2 h a day for 6 months to each leg in turn. The study lasted 1 year. Women were also given daily 1 g of Calcium and 800 IU of vitamin D (Calcichew D 3 forte Shire, UK). Lumbar spine BMD decreased by 0.5% at 12 months compared with baseline (mean difference 0.005 g/cm(2), 95% C.I -0.2287 to 0.03459, P = 0.28). At 12 months the right femoral neck BMD increased by 3% compared with baseline (mean 0.811 +/- 0.08, P = 0.22), while the left increased 2% (0.783 +/- 0.06, P = 0.16). There was no change in BMD at the distal tibia or heels and no site effect of the compression. The fat mass decreased by 4.6% in the right leg and 5% in the left leg (P = 0.005 and 0.003, respectively). Tissue thickness did not change. The analysis of the interaction between the degree of exercise and change in BMD showed a statistically significant increase in right femoral neck BMD following 6 months of right leg intermittent compression, but only in women whose exercise was minimal (P = 0.029). This effect was not seen in the left femur possibly due to the reduced number of patients who completed the study in this group. These preliminary results indicate that intermittent pneumatic leg compression may have a role in osteoporosis prevention. It may provide a mean of inhibiting decline in femoral neck BMD, particularly in sedentary women.

Aged↗

PubMed2005

HVS-based medical image compression.

INTRODUCTION: With the promotion and application of digital imaging technology in the medical domain, the amount of medical images has grown rapidly. However, the commonly used compression methods cannot acquire satisfying results. METHODS: In this paper, according to the existed and stated experiments and conclusions, the lifting step approach is used for wavelet decomposition. The physical and anatomic structure of human vision is combined and the contrast sensitivity function (CSF) is introduced as the main research issue in human vision system (HVS), and then the main designing points of HVS model are presented. On the basis of multi-resolution analyses of wavelet transform, the paper applies HVS including the CSF characteristics to the inner correlation-removed transform and quantization in image and proposes a new HVS-based medical image compression model. RESULTS: The experiments are done on the medical images including computed tomography (CT) and magnetic resonance imaging (MRI). At the same bit rate, the performance of SPIHT, with respect to the PSNR metric, is significantly higher than that of our algorithm. But the visual quality of the SPIHT-compressed image is roughly the same as that of the image compressed with our approach. Our algorithm obtains the same visual quality at lower bit rates and the coding/decoding time is less than that of SPIHT. CONCLUSIONS: The results show that under common objective conditions, our compression algorithm can achieve better subjective visual quality, and performs better than that of SPIHT in the aspects of compression ratios and coding/decoding time.

Algorithms↗

PubMed2004

Effects of dynamic compressive loading on chondrocyte biosynthesis in self-assembling peptide scaffolds.

Dynamic mechanical loading has been reported to affect chondrocyte biosynthesis in both cartilage explant and chondrocyte-seeded constructs. In this study, the effects of dynamic compression on chondrocyte-seeded peptide hydrogels were analyzed for extracellular matrix synthesis and retention over long-term culture. Initial studies were conducted with chondrocyte-seeded agarose hydrogels to explore the effects of various non-continuous loading protocols on chondrocyte biosynthesis. An optimized alternate day loading protocol was identified that increased proteoglycan (PG) synthesis over control cultures maintained in free-swelling conditions. When applied to chondrocyte-seeded peptide hydrogels, alternate day loading stimulated PG synthesis up to two-fold higher than that in free-swelling cultures. While dynamic compression also increased PG loss to the medium throughout the 39-day time course, total PG accumulation in the scaffold was significantly higher than in controls after 16 and 39 days of loading, resulting in an increase in the equilibrium and dynamic compressive stiffness of the constructs. Viable cell densities of dynamically compressed cultures differed from free-swelling controls by less than 20%, demonstrating that changes in PG synthesis were due to an increase in the average biosynthesis per viable cell. Protein synthesis was not greatly affected by loading, demonstrating that dynamic compression differentially regulated the synthesis of PGs. Taken together, these results demonstrate the potential of dynamic compression for stimulating PG synthesis and accumulation for applications to in vitro culture of tissue engineered constructs prior to implantation.

Animals↗

PubMed2004

Anisotropic hydraulic permeability in compressed articular cartilage.

The extent to which articular cartilage hydraulic permeability is anisotropic is largely unknown, despite its importance for understanding mechanisms of joint lubrication, load bearing, transport phenomena, and mechanotransduction. We developed and applied new techniques for the direct measurement of hydraulic permeability within statically compressed adult bovine cartilage explant disks, dissected such that disk axes were perpendicular to the articular surface. Applied pressure gradients were kept small to minimize flow-induced matrix compaction, and fluid outflows were measured by observation of a meniscus in a glass capillary under a microscope. Explant disk geometry under radially unconfined axial compression was measured by direct microscopic observation. Pressure, flow, and geometry data were input to a finite element model where hydraulic permeabilities in the disk axial and radial directions were determined. At less than 10% static compression, near free-swelling conditions, hydraulic permeability was nearly isotropic, with values corresponding to those of previous studies. With increasing static compression, hydraulic permeability decreased, but the radially directed permeability decreased more dramatically than the axially directed permeability such that strong anisotropy (a 10-fold difference between axial and radial directions) in the hydraulic permeability tensor was evident for static compression of 20-40%. Results correspond well with predictions of a previous microstructurally-based model for effects of tissue mechanical deformations on glycosaminoglycan architecture and cartilage hydraulic permeability. Findings inform understanding of structure-function relationships in cartilage matrix, and suggest several biomechanical roles for compression-induced anisotropic hydraulic permeability in articular cartilage.

Animals↗

PubMed2005

Permeability of human medial collateral ligament in compression transverse to the collagen fiber direction.

This study quantified the apparent and intrinsic hydraulic permeability of human medial collateral ligament (MCL) under direct permeation transverse to the collagen fiber direction. A custom permeation device was built to apply flow across cylindrical samples of ligament while monitoring the resulting pressure gradient. MCLs from 5 unpaired human knees were used (donor age 55 +/- 16 yr, 4 males, 1 female). Permeability measurements were performed at 3 levels of compressive pre-strain (10%, 20% and 30%) and 5 pressures (0.17, 0.34, 1.03, 1.72 and 2.76 MPa). Apparent permeability was determined from Darcy's law, while intrinsic permeability was determined from the zero-pressure crossing of the pressure-permeability curves at each compressive pre-strain. Resulting data were fit to a finite deformation constitutive law [Journal of Biomechanics 23 (1990) 1145-1156]. The apparent permeability of human MCL ranged from 0.40 +/- 0.05 to 8.60 +/- 0.77 x 10(-16) m(4)/Ns depending on pre-strain and pressure gradient. There was a significant decrease in apparent permeability with increasing compressive pre-strain (p=0.024) and pressure gradient (p<0.001), and there was a significant interaction between the effects of compressive pre-strain and pressure (p<0.001). Intrinsic permeability was 14.14 +/- 0.74, 6.30 +/- 2.13 and 4.29 +/- 1.71 x 10(-16) m(4)/Ns for compressive pre-strains of 10%, 20% and 30%, respectively. The intrinsic permeability showed a faster decrease with increasing compressive pre-strain than that of bovine articular cartilage. These data provide a baseline for investigating the effects of disease and chemical modification on the permeability of ligament and the data should also be useful for modeling the poroelastic material behavior of ligaments.

Anisotropy↗

PubMed2006

Effects of damage in the articular surface on the cartilage response to injurious compression in vitro.

Macroscopic structural damage to the cartilage articular surface can occur due to slicing in surgery, cracking in mechanical trauma, or fibrillation in early stage osteoarthrosis. These alterations may render cartilage matrix and chondrocytes susceptible to subsequent mechanical injury and contribute to progression of degenerative disease. To examine this hypothesis, single 300 microm deep vertical slices were introduced across a diameter of the articular surface of osteochondral explant disks on day 6 after dissection. Then a single uniaxial unconfined ramp compression at 7 x 10(-5) or 7 x 10(-2) s(-1) strain rate to a peak stress of 3.5 or 14 MPa was applied on day 13 during which mechanical behavior was monitored. Effects of slices alone and together with compression were measured in terms of explant swelling and cell viability on days 10 and 17. Slicing alone induced tissue swelling without significant cell death, while compression alone induced cell death without significant tissue swelling. Under low strain rate loading, no differences in the response to injurious compression were found between sliced and unsliced explants. Under high strain rate loading, slicing rendered cartilage more easily compressible and appeared to slightly reduce compression-induced cell and matrix injury. Findings highlight microphysical factors important to cartilage mechanical injury, and suggest ways that macroscopic structural damage may accelerate or, in certain cases, possibly slow the progression of cartilage degeneration.

Animals↗

PubMed2005

Solute convection in dynamically compressed cartilage.

Chondrocytes depend upon solute transport within the avascular extracellular matrix of articular cartilage for many of their biological activities. Alterations to solute transport parameters may therefore mediate the cell response to tissue compression. While interstitial solute transport may be supplemented by convection during dynamic tissue compression, matrix compression is also associated with decreased diffusivities. Such trade-offs between increased convection and decreased diffusivities of solutes in dynamically compressed cartilage remain largely unexplored. We measured diffusion and convection coefficients of a wide range of solutes in mature bovine cartilage explant disks subjected to radially unconfined axial ramp compression and release. Solutes included approximately 500 Da fluorophores bearing positive and negative charges, and 10 kDa dextrans bearing positive, neutral, and negative charges. Significantly positive values of convection coefficients were measured for several different solutes. Findings therefore support a role for solute convection in mediating the cartilage biological response to dynamic compression.

Animals↗

PubMedDate not supplied

Osteoporotic compression fractures of the spine; current options and considerations for treatment.

BACKGROUND CONTEXT: Vertebral compression fractures affect at least one-fourth of all postmenopausal women. The most significant risk factor is osteoporosis, most commonly seen among Caucasian women a decade or so after menopause. Osteoporosis typically results from inadequate accumulation of bone mass during childhood and early adulthood followed by rapid resorption after menopause. Primary treatment of osteoporosis includes consideration of underlying metabolic abnormalities and provision of supplemental calcium/vitamin D in conjunction with bisphosphonates or calcitonin, or both. Routine hormone replacement therapy has fallen out of favor because of concerns regarding adverse effects identified in long-term follow-up studies. Acute osteoporotic vertebral compression fracture management includes bracing, analgesics, and functional restoration. Patients with chronic pain beyond 2 months may be appropriate candidates for vertebral body augmentation, ie, vertebroplasty or balloon tamp reduction. Open surgical management with decompression and stabilization should be reserved for the rare patient with neural compression and progressive deformity with neurologic deficits. PURPOSE: To review current principles in the evaluation and treatment of osteoporotic compression fractures of the spine. STUDY DESIGN/SETTING: A literature review on management of the osteoporotic spine. METHODS: MEDLINE search of all English-language literature published between 1981 and 2005 on surgical and nonsurgical treatment of the osteoporotic spine. The references selected for listing at the conclusion of this review are those containing specific information cited within the text. RESULTS: Over 200 separate scientific and clinical studies addressing the epidemiology, pathophysiology, diagnosis, and treatment of osteoporotic vertebral compression fractures were reviewed. CONCLUSIONS: Osteoporotic vertebral compression fractures are a common presenting complaint to spinal care specialists. Thorough differential diagnosis should be considered before attributing fractures to osteoporosis. Appropriate evaluation and medical treatment of underlying osteoporosis should be recommended or instituted. Nonsurgical management of the spinal fracture should focus on pain control and maximizing functional outcome. The role of surgical treatment remains controversial and should be reserved for patients who fail initial nonsurgical management options.

Bone Density Conservation Agents↗

PubMed1997

Lower extremity iatrogenic nerve injury due to compression during intraabdominal surgery.

BACKGROUND: latrogenic nerve injury due to poor positioning and external compression is a common surgical complication. However, sciatic neuropathy from external compression and femoral nerve injury after self-retaining retraction are less-published complications. METHODS: Surgical Morbidity and Mortality Reports from 1986 through 1995 were reviewed to identify femoral and sciatic neuropathies following intraabdominal vascular and general surgeries. RESULTS: Two sciatic and 5 femoral neuropathies were reported, an incidence of approximately 0.17% of abdominal cases. Sciatic injuries were attributed to external compression, whereas femoral neuropathies were due to compression by self-retaining retraction. The 3 female and 4 male patients had a mean age of 53.4 years, and no patient had a prior history of peripheral neuropathy. Mean operating time for sciatic injuries was 8.2 hours, versus 4.3 hours for femoral neuropathies. Both patients with sciatic neuropathy had complete resolution of symptoms, compared with 1 femoral neuropathy patient. Two femoral neuropathies were permanent, 1 had partial resolution and 1 had improvement at 4 months but was lost to follow-up. CONCLUSIONS: Sciatic and femoral compression neuropathies are rare but serious complications of abdominal surgery. When retracting in the deep pelvis, consideration should be given to using small, well-padded retractor blades and repositioning these regularly. Prevention of sciatic nerve compression requires careful padding of the table surface, especially for longer cases.

Abdomen↗

PubMed1998

The influence of compressive loading on growth of cartilage of the mandibular condyle in vitro.

The purpose of this study was to clarify the change in mandibular condyles under compressive loading. An organ-culture system of fetal rat mandibular condyles was used, and mechanical loading was generated by compressing the gas phase within a closed chamber. After the culture period, with compressive loading, type I collagen and fibronectin were observed in the lower half of the hypertrophic chondrocyte layer in the mandibular condyles; in contrast, without compressive loading, there was no such reaction. The size of the condyle was not increased by compressive loading. These results suggest that intermittent compressive loading could induce type I collagen and fibronectin production by chondrocytes.

Animals↗

PubMed2000

Depth of cure and compressive strength of dental composites cured with blue light emitting diodes (LEDs).

OBJECTIVE: The primary objective of this pilot study was to test the hypotheses that (i) depth of cure and (ii) compressive strength of dental composites cured with either a light emitting diode (LED) based light curing unit (LCU) or a conventional halogen LCU do not differ significantly. The second objective of this study was to characterise irradiance and the emitted light spectra for both LCUs to allow comparisons between the units. METHODS: Dental composite (Spectrum TPH, shades A2 and A4) was cured for 40 s with either a commercial halogen LCU or a LED LCU, respectively. The LED LCU uses 27 blue LEDs as the light source. The composites' depth of cure was measured for 10 samples of 4 mm diameter and 8 mm depth for each shade with a penetrometer. The results were compared using a Student's t-test. Compressive strengths were determined after 6 and 72 h, for six samples of 4 mm diameter and 6 mm depth for each shade after being polymerised for 40 s from each end of the mould. Groups were compared using a three way ANOVA. RESULTS: The conventional halogen LCU cured composites significantly (p < 0.05) deeper (6.40 mm A2, 5.19 mm A4) than did the LED LCU (5.33 mm A2, 4.27 mm A4). Both units cured the composite deeper than required by both ISO 4049 and the manufacturer. A three way ANOVA showed that there were no significant differences in the compressive strengths of samples produced with either the LED LCU or the halogen LCU (p = 0.460). Significant differences in compressive strength of samples stored for 6 and 72 h (p = 0.0006) and of samples of different shades (p = 0.035) were found as confirmed by the three way ANOVA. The light spectra of both units differed strongly. While the halogen LCU showed a broad distribution of wavelengths with a power peak at 497 nm, the LED LCU emitted most of the generated light at 465 nm. The LED LCU produced a total irradiance of 350 mW cm-2 whereas the halogen LCU produced a total irradiance of 755 mW cm-2. SIGNIFICANCE: The results showed that both units provided sufficient output to exceed minimum requirements in terms of composites' depth of cure according to ISO 4049 and the depth of cure and the composites' compressive strength stated by the manufacturer. Compressive strengths of dental composites cured under laboratory conditions with a LED LCU were statistically equivalent to those cured with a conventional halogen LCU. With its inherent advantages, such as a constant power output over the lifetime of the diodes, LED LCUs have great potential to achieve a clinically consistent quality of composite cure.

Analysis of Variance↗

PubMed2002

Mechanical compression alters gene expression and extracellular matrix synthesis by chondrocytes cultured in collagen I gels.

Articular cartilage responds to its mechanical environment through altered cell metabolism and matrix synthesis. In this study, isolated articular chondrocytes were cultured in collagen type I gels and exposed to uniaxial static compression of 0%, 25%, or 50% of original thickness for 0.5, 4, and 24 h, and to oscillatory (25 +/- 4%, 1 Hz) compression for 24 h. The cellular response was assessed through competitive and real-time RT-PCR to quantify expression of genes for collagen type I, collagen type II, and aggrecan core protein, and through radiolabelled proline and sulfate incorporation to quantify protein and proteoglycan synthesis rates. Static compression for 24 h inhibited expression of collagen I and II mRNAs and inhibited 3H-proline and 35S-sulfate incorporation. The mRNA expression exhibited transient fluctuations at intermediate time points. Oscillatory compression had no effect upon mRNA expression, and 24 h after release from static compression, there was no difference in collagen II or aggrecan mRNA, while there was an inhibition of collagen I. We conclude that the chondrocytes maintained some aspects of their ability to sense and respond to static compression, despite a biochemical and mechanical environment which is different from that in tissue. This suggests that mechanical stimuli may be useful in modulating chondrocyte metabolism in tissue engineering systems using fibrillar protein scaffolds.

Aggrecans↗

PubMed1997

Local control and survival in spinal cord compression from lymphoma and myeloma.

BACKGROUND: Between 1979 and 1989, 48 cases of extradural spinal cord and cauda equina compression in patients with lymphoma (24) and myeloma (24) received local radiation therapy for control of cord compression. Twenty five (52%) of the cases were treated by surgical decompression prior to irradiation. Thirty five (73%) of the cases received chemotherapy following the diagnosis of spinal cord compression. Post-treatment outcome was assessed at a minimum follow-up of 24 months to determine the significant clinical and treatment factors following irradiation. RESULTS: Seventeen (71%) of the lymphoma and 15 (63%) of the myeloma patients achieved local control, here defined as improvement to, or maintenance of ambulation with minimal or no assistance for 3 months from the start of radiotherapy. At a median follow-up of 30 (2-98) for the lymphoma and 10 (1-87) months for the myeloma patients, the results showed that survival following local radiation therapy for cord compression was independently influenced by the underlying disease type in favour of lymphoma compared to myeloma (P < 0.01). The median duration of local control and survival figures were 23 and 48 months for the lymphomas compared to 4.5 and 10 months for the myeloma cases. Survival was also independently influenced by preservation of sphincter function at initial presentation (P < 0.02) and the achievement of local control following treatment (P < 0.01). DISCUSSION: We conclude that while disease type independently impacts on outcome following treatment of spinal cord compression in lymphoma and myeloma, within both of these disease types the achievement of local control of spinal cord compression is an important management priority, for without local control survival may be adversely affected.

Adolescent↗

PubMed1997

Spinal cord compression in prostate cancer: treatment outcome and prognostic factors.

BACKGROUND AND PURPOSE: Spinal cord compression (SCC) is an important complication of metastatic prostate cancer. We have analysed patients treated at the Royal Marsden Hospital to assess treatment outcome and prognostic factors in this patients group. MATERIALS AND METHODS: We performed retrospective analysis of 69 patients with spinal cord compression and prostate cancer treated at the Royal Marsden Hospital. RESULTS: At presentation 40 (58%) patients were non-ambulant and 52% were catheterised. Diagnosis was established by myelography in 42% and magnetic resonance imaging (MRI) in 47% of patients. MRI detected significantly more patients with multiple sites of compression (51 versus 7%, P < 0.001). SCC was present at the initial diagnosis of prostatic cancer in 13 patients and 17 patients had received no hormone treatment prior to diagnosis. Following treatment 36 (52%) patients had a functional improvement of motor power with 25/40 (63%) non-ambulant patients becoming ambulant. Seventy-seven percent of patients who had eventual improvement had some improvement in power within 7 days. On multivariate analysis a single level of compression, no previous hormone therapy and a young age (<65 years) predicted for better outcome. When these factors were included an increased radiation dose (>30 Gy) or the addition of surgery did not improve the functional outcome. Following initial recovery; there was a 45% risk of developing a further episode of cord compression at the same or new site by 2 years with a median time to progression of 236 days (range 47-1215 days). The median survival was 115 days (range 5-2016 days) with 25% of patients surviving for 2 years. Patients with no prior hormone therapy had a median survival of 627 days (range 46-1516 days). Other predictors of improved survival on multivariate analysis were a single site of compression and a haemoglobin over 12 g. CONCLUSIONS: Treatment of SCC in prostate cancer results in improved motor function in the majority of patients. Long-term survival is possible, especially in good performance status patients with no prior hormone treatment. Survivors remain at high risk of subsequent neurological relapse. An early improvement in motor power is a strong predictor of subsequent functional improvement. MRI detects additional sites of asymptomatic SCC which makes it the investigation of choice.

Aged↗