Factors affecting isokinetic muscle strength before and after anterior cruciate ligament reconstruction

The purpose of this study was to evaluate the factors affecting muscle strength of ACL-deficient knees before and after ACL reconstruction. The study included 122 male patients who underwent primary ACL reconstruction with a bone-patellar tendon-bone autograft. Preoperative loss and change in muscle strength in both extensor and flexor muscle groups after ACL reconstruction were calculated separately at 60 degrees/sec and 180 degrees/sec angular velocities. We evaluated the effect of surgical delay on the preoperative deficit and on its change after surgery. Muscle strength change after ACL reconstruction was also evaluated in relation to patient compliance to treatment. The longer the delay of ACL reconstruction the more the muscle strength deficit of flexor and extensor muscles increased. In the ACL deficient knees with high strength deficit, improvement in muscle strength was higher after ACL reconstruction for both muscle groups. When delay of ACL reconstruction was short and the patient was compliant to treatment, flexor muscle strength recovery was early. Shortening the delay to reconstruction had a positive influence on muscle strength after ACL reconstruction when preoperative muscle strength deficit was high.     

The role of parathyroid hormone measurements after surgery for primary hyperparathyroidism

BACKGROUND: During parathyroidectomy for primary hyperparathyroidism (pHPT), intraoperative parathyroid hormone (IOPTH) levels are used to confirm removal of all hyperfunctioning parathyroid tissue. The phenomenon of elevated parathyroid hormone (PTH) levels with normocalcemia after curative parathyroidectomy, seen in up to 40% of patients, continues to be an unexpected and unexplained finding. We therefore investigated whether postoperative PTH levels are as reliable as IOPTH levels in predicting cure after surgery for pHPT. METHODS: We reviewed our prospective database of consecutive patients undergoing surgery for pHPT between December 1999 and November 2004. Curative parathyroidectomy was defined as normocalcemia 6 months or longer postoperatively. RESULTS: A total of 328 patients who underwent 330 operations for pHPT had IOPTH measurements and serum follow-up calcium levels at 6 months or longer. Surgery was curative in 315 (95.5%) operations. IOPTH levels correctly predicted operative success in 98.2% (positive predictive value [PPV]. Postoperatively, the PPV of a normal PTH level at 1 week, 3 months, and 6 months was 97.1%, 97.3%, and 96.5%, respectively. Of all patients with an elevated postoperative PTH level at 1 week, 3 months, or 6 months, only 13.7%, 14.3%, and 14%, respectively, were not cured. CONCLUSIONS: Normal postoperative PTH levels reliably predict operative success. However, they do not improve upon results predicted by IOPTH levels. Elevated postoperative PTH levels do not predict operative failure in most patients. We propose that PTH measurements after surgery for pHPT may be misleading, costly, and not indicated in normocalcemic patients.     

Muscle strength is improved after parathyroidectomy in patients with primary hyperparathyroidism.

Fatigue and muscular weakness are prevalent symptoms in patients with primary hyperparathyroidism. This study examined muscular strength before and after operation in a group of eight patients with hyperparathyroidism and in a control group of seven patients with benign thyroid lesions. The maximum power grip, pronation and supination, and endurance for the same muscular movements, were studied by means of a computer program. Patients with hyperparathyroidism had impaired muscular strength compared with the controls but 12 months after operation a significant improvement of all muscular performance was observed. No such improvement was detectable among the controls. There was no correlation between the levels of serum calcium and parathyroid hormone and the measurements recorded before and after operation. Muscular impairment in hyperparathyroidism is measurable by an objective technique. Improvement occurs after surgery.     

Muscle structure and function before and after surgery for primary hyperparathyroidism.

In 23 unselected cases of primary hyperparathyroidism (pHPT), muscle strength, morphology and enzymatic activities were studied and electromyography (EMG) performed before and 6 months after surgical treatment. Hypercalcemia was mostly mild or moderate. Nine women undergoing surgery for benign thyroid conditions served as controls regarding muscle strength, while muscle morphologic and enzymatic data were compared with findings in healthy persons of similar age. Only three pHPT patients reported muscle weakness preoperatively, and two were subjectively improved after surgery. Muscle strength did not differ significantly before or after operation between patients and controls: After surgery both groups showed increased isokinetic muscle strength at higher angular velocities. Nor did muscle morphology differ between pHPT patients and controls. No conclusive EMG changes were found before or after surgery for pHPT but postoperatively the pHPT patients showed significant increase in glycolytic but not oxidative muscle enzymes, possibly reflecting early effect of pHPT on especially type II fibers, which previously were shown to be most extensively involved in pHPT. Otherwise no measurable negative effects of mild or moderate pHPT were found on muscle strength or function.     

Pre- and postoperative respiratory muscle strength in primary hyperparathyroidism

Muscle function in ten hyperparathyroid patients and six patients with benign thyroid disease was assessed by measuring maximal expiratory (Pe max) and inspiratory (Pi max) pressures before and 6-12 months after neck surgery. Pe max was improved in all the hyperparathyroid patients postoperatively (p less than 0.002), while the median value of Pi max was unchanged. In the control (thyroid) group there was no significant postoperative change in either Pe max or Pi max. It is concluded that normalization of hypercalcemia improves respiratory muscular capacity, which can be quantified by measuring maximal expiratory pressure.     

Identification of pathologic parathyroid glands in patients with primary hyperparathyroidism

r = 0.861, intact PTH assay). Eight of 9 patients with multiple-gland involvement had an elevated serum PTH (>2000 pg/ml in midportion and >200 pg/ml in intact PTH assays, respectively). No patient developed persistent or recurrent hyperparathyroidism. The serum PTH level was normalized by a resection of relatively enlarged glands in our cases. It is usual to explore all glands during surgery, and in cases with a high serum PTH level, multiple-gland involvement should also be considered. (Received for publication on Feb. 10, 1997; accepted on July 8, 1997)     

Evaluation of selected cognitive functions before and after surgery for primary hyperparathyroidism

Background and aims

Cognitive functions have been reported to be impaired in patient with primary hyperparathyroidism (pHPT). The aim of this psychological study was to evaluate cognitive disturbances in pHPT in relation to serum calcium levels before and after surgery.

Patients and methods

A prospective, case–control study with 1-year follow-up of 35 pHPT patients versus 35 matched controls was undertaken. All patients were tested before surgery and at 12–18?months following surgery with a battery of selected cognitive function psychological tools: Benton Visual Retention Test (BVRT), Wisconsin Card Sorting Test (WCST), Memory Verbal Learning Test (DCS), The Rey's Auditory Verbal Learning Test (RAVLT), Trail Making Test A & B, Verbal Fluency Test, and Beck Depression Inventory. In addition to psychological testing, serum calcium, parathyroid hormone and phosphate levels were evaluated.

Results

The following cognitive functions of pHPT patients versus controls were deteriorated before surgery: impaired concentration, decreased nonverbal learning process, difficulties in using direct memory, verbal fluency and visual constructive abilities. However, no correlation was found between serum calcium levels and the results of neuropsychological tests. In longitudinal comparison of pHPT patients before and 1?year after surgery, there was a significant improvement in visual memory, visual–constructive abilities and direct memory.

Conclusions

pHPT patients have significantly decreased concentration level, nonverbal learning process, access to verbal resources and constructional and visual memory ability. Thus, neuropsychological testing may be useful in the decision making for early surgery in patients with mild asymptomatic disease in order to avoid further deterioration of cognitive functions.     

Regional cerebral blood flow in patients with primary hyperparathyroidism before and after successful parathyroidectomy

BACKGROUND: Single-photon emission computed tomography (SPECT) is used to study cerebral blood flow and cerebral metabolism in various neuropsychiatric disorders. Reduced regional cerebral blood flow has been demonstrated in patients with depression and chronic fatigue, symptoms that are common in primary hyperparathyroidism. The aim of this study was to reveal possible changes in regional cerebral blood flow in patients with primary hyperparathyroidism before and after operative treatment. METHODS: This was a prospective study of regional cerebral blood flow in 16 consecutive women of median age 72 (range 50-82) years using SPECT with (99m)Tc-labelled hexamethylpropylenamine-oxime. The measurements were performed before and 2, 4 and 12 months after parathyroidectomy. The Montgomery and Asberg depression rating scale (MADRS) depression score was used as a parallel clinical test. RESULTS: Reduced (pathological) regional cerebral blood flow was seen before operation in 14 patients, 13 with a solitary adenoma and one with double adenoma. After surgery, this improved to normal values in 13, but was further reduced in one. In two patients with preoperative normal regional cerebral blood flow, both of whom were asymptomatic and had diffuse hyperplasia, a slight reduction was demonstrated. Eight patients had a pathological preoperative MADRS score, which normalized in seven after surgical treatment. CONCLUSION: The finding of reduced regional cerebral blood flow in patients with primary hyperparathyroidism followed by significant improvement after operation might influence the case for surgical treatment.     

Dynamics of parathyroid hormone release and serum calcium regulation after surgery for primary hyperparathyroidism

Analysis of 14 patients with primary hyperparathyroidism (HPT) prior to and during the first year after parathyroid surgery disclosed that the operation was associated with rapid reductions of intact serum parathyroid hormone (PTH) and total serum and ionized plasma calcium values. A decreased urinary calcium excretion, a gradual elevation of renal calcium reabsorption, a transient reduction of serum calcitriol, and a late increase in 25-hydroxycholecalciferol values were also noted. Dynamic tests of parathyroid function by EDTA infusion and an oral calcium load revealed a sigmoidal relationship between serum PTH and calcium levels, and that parathyroid surgery induced considerable changes in both the position and slope of the dose-response curve. It was also apparent that PTH release was submaximally stimulated event at periods of hypocalcemia. The findings substantiate that adjustments of PTH release to acute alterations of serum calcium occur along the prevailing dose-response relationship, while stimuli being maintained for longer periods of time induce compensatory shifts in the position and slope of this curve. It is further suggested that unknown factors with PTH-like function may participate in the calcium regulation after surgery for primary HPT.

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Resumen El análisis de 14 pacientes con hiperparatiroidismo primario (HPT) realizado antes y durante el primer año siguiente a cirugía paratiroidea demostró que la operación estuvo asociada con una reducción rápida del nivel sérico de la hormona paratiroidea intacta (PTH) y de los valores séricos de calcio total y de calcio ionizado. También se observó una disminución en la excreción urinaria de calcio, una elevación gradual de la reabsorción renal de calcio, una reducción transitoria del calcitriol sérico y un incremento tardío de los valores de 25-hidroxicolecalciferol. Las pruebas dinámicas de función paratiroidea mediante la infusión de EDTA y una carga oral de calcio revelaron una relación que se expresa como curva sigmoidea entre los niveles séricos de PTH y los de calcio, y que la cirugía paratiroidea indujo cambios considerables tanto en la posición como en la inclinación de la curva dosis-dependiente. También resultó aparente que la liberación de PTH aparecía submáximamente estimulada aun en periodos de hipocalcemia. Los hallazgos confirman que los ajustes en la liberación de PTH, ante alteraciones agudas, en el nivel de calcio sérico se producen según la relación dosis-dependiente, en tanto que los estímulos sostenidos por más prolongados periodos de tiempo inducen cambios compensatorios en la posición y en la inclinación de la curva. Además, sugieren que otros factores desconocidos con funcíones similares a las de la PTH pueden tener participación en la regulación del calcio después de efectuada la cirugía para HPT primario.

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Résumé L'étude de 14 patients atteints d'hyperparathyroïdie primaire (HPT) avant et durant la première année suivant la chirurgie a mis en évidence que l'intervention s'accompagnait d'une rapide diminution de la parathormone sérique (PTH) et des taux de calcium total et calcium ionisé plasmatiques. Une diminution de la calciurie, une élèvation progressive de la réabsorption rénale du calcium, une réduction transitoire du calcitriol sérique et une élèvation retardée du 25 hydroxycholecalciférol ont été également notées. Des tests dynamiques de la fonction parathyroïdienne par perfusion d'EDTA et charge orale en calcium ont montré une relation sigmoïde entre la PTH sérique et la calcémie. La chirurgie parathyroïdienne induit des modifications notables à la fois de la position et de la pente de la courbe dose-réponse. Il est également apparu que la libération de PTH était stimulée de façon sous maximale même en cas d'hypocalcémie. Ces résultats établissent que l'adjustement de la libération de PTH à des modifications brusques de la calcémie se fait selon la prévalence de la relation dose-réponse, tandis que des stimuli persistent sur de longues périodes induisent des changements de position et de pente de cette courbe. Il est de plus suggéré que des facteurs inconnus ayant une fonction PTH libre peuvent participer à la régulation du calcium après la chirurgie pour HPT primaire.

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Presented at the International Association of Endocrine Surgeons in Stockholm, Sweden, August, 1991.     

Evaluation of glucose tolerance,insulin secretion,and insulin action in patients with primary hyperparathyroidism before and after surgery

Summary Glucose tolerance, insulin secretion, and insulin sensitivity were evaluated in 8 asymptomatic patients with primary hyperparathyroidism (PHPT) before and at least 8 weeks after surgical correction of PHPT by means of the hyperglycemic clamp technique. In addition, 15 sex- and agematched control subjects were investigated for comparative reasons by the same technique. Glucose metabolized (M) during the hyperglycemic clamp was not significantly (NS) different between patients with PHPT and controls (7.9±2.3 vs. 6.3±1.9 mg/kg/min). However, insulin secretion (I) was significantly elevated in patients with PHPT compared to controls (87±17 vs. 45±12 μU/ml,P<0.05). The calculated insulin sensitivity index, (M/I) was significantly reduced in PHPT compared to controls (11.0±2.1 vs. 15.2±1.4 mg/kg/min per μU/ml×100,P<0.05). Comparing patients with PHPT before and after surgery, the M value, which is a measure of glucose tolerance, was not significantly different (7.9±2.3 vs. 7.8±1.5 mg/kg/min). However, insulin secretion was significantly lower after surgical correction of PHPT compared to the preoperative situation (48±9 μU/ml vs. 87±17 μU/7 ml,P<0.01). The calculated M/I rose significantly after surgery compared to the preoperative value (11±2.1 vs. 17.6±2.7 mg/kg/min per μU/ml ×100,P<0.001). We conclude that disturbed carbohydrate metabolism such as insulin hypersecretion and insulin resistance, in patients with PHPT is an early finding in this disease and that these early disturbances in glucose metabolism are, however, fully reversible. Correction of disturbed carbohydrate metabolism in PHPT might be a distinct argument for early surgical intervention in this disease.     

Arterial distensibility and pulse wave velocity in patients with primary hyperparathyroidism before and after parathyroidectomy

AIMS: There is evidence that secondary hyperparathyroidism alters arterial vessel wall properties. However, it is unclear whether effects of parathyroid hormone (PTH) on the vascular wall are direct or permissive and related to hypertension and renal failure. To assess early direct effects of PTH on large artery wall properties isobaric distensibility (DC), pulse wave velocity (PWV) and intima-media thickness (IMT) were studied before and after parathyroidectomy (Ptx) in patients with primary hyperparathyroidism (pHPT). METHODS: DC and IMT of the brachial and carotid artery were measured by echo-tracking and tonometry, PWV by the automatic Complior-device at baseline and 6 months after Ptx in 20 patients with pHPT (data mean +/- SEM, age 45+/-5 years, PTH 240+/-61 ng/l). Cardiovascular risk factors like diabetes, hypertension, renal insufficiency and hypercholesterolemia were excluded. Twenty healthy volunteers matched for age, sex and blood pressure served as controls. RESULTS: Six months after Ptx, PTH decreased to normal; however, blood pressure levels and vessel wall parameter remained unchanged. At baseline, there were no significant differences in brachial and carotid IMT (0.48+/-0.04 and 0.62+/-0.04 mm vs. 0.47+/-0.06 and 0.61+/-0.06 mm), radial and aortic PWV (9.1+/-0.4 and 9.9+/-0.7 m/s vs. 9.2+/-0.5 and 10.0+/-0.6 m/s), brachial and isobaric carotid DC (10.1+/-1.4 and 19.5+/-3.4 10(-3)/kPa vs. 9.1+/-0.9 and 20.4+/-3.2 10(-3)/kPa) or artery diameter between patients and controls. CONCLUSIONS: Structural and viscoelastic properties of large arteries are not disturbed and not influenced by parathyroidectomy in patients with early pHPT devoid of hypertension and renal disease. We conclude that increased PTH levels per se are not associated with alterations of mechanical arteriall wall properties; permissive factors like renal insufficiency may be necessary to mediate vessel wall alterations in patients with hyperparathyroidism.     

Function in athymic nude mice of parathyroid heterografts from patients with primary hyperparathyroidism and secondary hyperparathyroidism

Heterotransplantation of adenomatous parathyroid glandular tissue from humans with primary hyperparathyroidism into athymic nude mice creates a unique animal model of this disease. The mice manifest high concentrations of both midregion/C-terminal human parathyroid hormone and biologically active intact human parathyroid hormone relative to either mice with no implants or mice that received normal human parathyroid tissue. Secretion of these substances is maintained in most mice for at least 9 to 13 months after implantation. In addition, animals that have experienced implantation exhibit other characteristics associated with human primary hyperparathyroidism including relative hypercalcemia and increased renal 25-hydroxyvitamin D-1 alpha-hydroxylase activity. We also measured these parameters in a group of nude mice that received transplantation of a similar mass of hyperplastic parathyroid tissue that was obtained from patients with uremic secondary hyperparathyroidism. Although we hypothesized that the level of human parathyroid hormone secretion from these implants would fall over time in response to the normal host environment, hormone levels remained as high as those in recipients of adenomatous heterografts, even after 9 to 13 months. Moreover, similar biologic effect of the excess parathyroid hormone (i.e., relative hypercalcemia, hyperphosphatasemia, and increased 1,25-dihydroxyvitamin D biosynthesis) were detected. These animal models should prove extremely useful in supplementing our understanding of hyperparathyroid disorder in man.     

Hyperthyroxinemia after surgery for primary hyperparathyroidism

Episodes of transient thyrotoxicosis after surgery for primary hyperparathyroidism have previously been described, and surgical trauma to the thyroid gland has been suggested as an etiologic factor. However, there are several links between the thyroid and parathyroid hormonal systems, and therefore other explanations are possible as well. In this study we investigate pre- and postoperative serum levels of thyroid hormones in 20 patients operated upon because of primary hyperparathyroidism. The mean (SD) serum levels of T₄ increased from 16(2) pmol/l preoperatively to 21(6) pmol/l on the fourth postoperative day (P < 0.01), and four (20%) of the patients developed biochemical thyrotoxicosis in the immediate postoperative period. The serum levels of T4 on the fourth postoperative day correlated highly with preoperative serum levels of PTH (r = 0.75;P < 0.001). This suggests that biochemical thyrotoxicosis in the immediate postoperative period after operation for primary hyperparathyroidism is not uncommon and could be related to the disease rather than to surgical trauma.

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Hyperthyroxinämie nach operation wegen hyperparathyreoidismus

Zusammenfassung Es gibt Berichte über transiente Thyrotoxikose nach Operation wegen primärem Hyperparathyreoidismus, und als ätiologischer Faktor wurde die chirurgische Läsion der Schilddrüse angegeben. Da jedoch Verbindungen zwischen dem thyroiden und dem parathyreoiden Hormonalsystem bestehen, sind auch andere Erklärungen denkbar. In der vorliegenden Studie wurden bei 20 wegen primärem Hyperparathyreoidismus operierten Patienten die prä- und postoperativen Schilddrüsenhormonspiegel untersucht. Bei 2 Patienten stieg der mittlere T4-Spiegel (±SD) von präoperativ 16 auf 21 pmol/1 am 4. Tag p.o. (p < 0,01), und bei 4 Patienten (20%) kam es gleich nach der Operation zu einer biochemischen Thyreotoxikose. Die T₄-Serumspiegel am 4. postoperativen Tag korrelierten stark mit den präoperativen PTH-Serumspiegeln (r = 0,75,p < 0,001). Daraus läßt sich ableiten, daß biochemische Thyreotoxikose unmittelbar nach Operation wegen primärem Hyperparathyreoidismus nichts Ungewöhnliches ist und eher auf die Erkrankung zurückgeführt werden könnte als auf das operationsbedingte Trauma.

     

Hyperthyroidism after surgery for primary hyperparathyroidism

Background: The coexistence of hyperthyroidism and primary hyperparathyroidism (pHPT) has been reported. We have questioned whether hypercalcemia or surgical trauma contribute to transient hyperthyroidism following parathyroid surgery. Methods: Twenty-six pHPT and eleven breast cancer patients were compared regarding pre-, peri- and postoperative thyrotropin (TSH), free thyroxine (T4) and free triiodothyronine (T3) concentrations. Thyroglobulin concentration, occurrence of autonomous thyroid nodules, and variables reflecting surgical trauma were compared in pHPT patients with and without postoperative hyperthyroidism. Results: Postoperatively, eleven pHPT patients demonstrated T4 and T3 concentrations above normal, and nine developed symptoms of mild thyrotoxicosis. A parallel rise in TSH and T4 concentrations was seen during both parathyroid and breast cancer surgery. Compared with patients with no postoperative hyperthyroidism, patients with postoperative hyperthyroidism showed a parallell rise in mean thyroglobulin and T4/T3 concentrations as well as higher thyroglobulin concentrations. However, there was no difference in variables assessing surgical trauma nor in occurrence of autonomous thyroid nodules. The peri-operative rise in TSH was preceded by a decrease in calcium. Conclusion: Transient hyperthyroidism after parathyroid surgery is not infrequent. The condition seems to be self-limiting, since symptoms invariably subsided without treatment. Manipulation of the thyroid gland is most likely the major contributing factor to postoperative hyperthyroidism. However, it may not be the sole explanation, since our data suggest a more multifactorial scenario. Received: 9 April 1999; in revised form: 25 August 1999 Accepted: 26 August 1999     

Large retrosternal parathyroid carcinoma with primary hyperparathyroidism

Parathyroid carcinoma is an uncommon cause of parathyroid hormone (PTH)-dependent hypercalcaemia, accounting for less than 1% of all cases of hyperparathyroidism. Parathyroid carcinoma is an indolent tumour with rather low malignant potential. Consideration of parathyroid carcinoma in the differential diagnosis of hypercalcaemic disorders is important because the morbidity and mortality are substantial and the best prognosis is associated with early recognition and surgical resection. Clinical indicators favouring parathyroid carcinoma over benign disease include markedly raised serum calcium levels, PTH and alkaline phosphatase. A palpable neck mass with both kidney and skeletal manifestations also give a high index of suspicion of parathyroid carcinoma. Histopathology alone is not sufficient to diagnose parathyroid cancer; it has to be correlated with the clinical findings. The initial and most effective treatment for parathyroid carcinoma is complete resection of the primary lesion, and repeated operations for recurrence are useful. The prognosis of parathyroid carcinomas is quite variable; 5-year survival rates vary from 40% to 86%, while the 10-year survival rate is approximately 49%. We report a case of parathyroid carcinoma occurring in a 55-year-old woman who presented with bone pain and hypercalcaemia.     

Reelevation of parathyroid hormone level after parathyroidectomy in patients with primary hyperparathyroidism: importance of decreased renal parathyroid hormone sensitivity

BACKGROUND: We hypothesized that impaired peripheral sensitivity to parathyroid hormone (PTH) may play a role in reelevation of PTH after successful operation for primary hyperparathyroidism (pHPT). METHODS: Factors affecting reelevation of PTH were determined in 90 patients who underwent parathyroidectomy for pHPT. PTH/nephrogenous cyclic adenosine monophosphate ratio, as an index of renal resistance to PTH, was examined in relation to factors shown to influence reelevation of PTH. RESULTS: Serum PTH levels were elevated above the upper limit of normal in 23 patients (26%) at 1 week and in 39 patients (43%) at 1 month after parathyroidectomy. These 39 normocalcemic patients with elevated serum PTH at 1 month after parathyroidectomy had a higher preoperative serum level of PTH and lower serum phosphate and 25-hydroxyvitamin D (25OHD) concentrations than those with normal PTH (n = 59). Elevated PTH and low 25OHD were shown by multivariate analysis to be significant predictors of reelevation of PTH. Renal resistance to PTH was higher in patients with vitamin D deficiency or renal insufficiency than in patients with normal serum vitamin D concentrations or normal renal function, and it increased according to increases in levels of PTH. CONCLUSIONS: The mechanism of PTH reelevation in patients with pHPT after successful parathyroidectomy appears to be renal resistance to PTH.     

Predictors of isokinetic back muscle strength in patients with low back pain

STUDY DESIGN: Testing for trunk muscle strength was performed on 105 patients with chronic low back pain. OBJECTIVES: To investigate prediction of isokinetic back muscle strength in patients with low back pain. SUMMARY OF BACKGROUND DATA: The clinical evaluation of patients with chronic low back pain often in difficult because of discrepancy between disability and impairment. The isokinetic trunk device was developed as a tool for objective assessment of back muscle strength. However, the performance of patients depends on radiologic abnormalities of the spine, conditions of the back muscles, and various psychosocial factors. Studies are warranted that address how these variables influence back muscle strength. METHODS: The patients with chronic low back pain were tested by an isokinetic trunk muscle strength test (Cybex TEF, Ronkonkoma, NY). In addition, the following variables were recorded: gender, age, body mass index, emotional distress, pain on exertion, self-efficacy for pain, degenerative changes of the lumbar spine, cross-sectional area, and density of the erector spinae muscles. The three latter variables were estimated by computed tomography scans. The sum of the total work performed during isokinetic extension strength test was the dependent variable in a multiple regression analysis, and anthropometric, demographic, psychological, and radiologic factors were independent variables. RESULTS: Gender, cross-sectional muscle area, and pain on exertion were the most powerful predictors of isokinetic back muscle strength. The final regression model, which included these variables, could account for approximately 40% of the variability in back muscle strength. CONCLUSION: For assessing the results of an isokinetic trunk muscle strength test, cross-sectional muscle area, gender, and pain on exertion should be taken into account.     

Apoptosis in parathyroid hyperplasia of patients with primary or secondary uremic hyperparathyroidism

BACKGROUND: Chronic oversecretion of parathyroid hormone (PTH) is associated with parathyroid hyperplasia, reflecting a disturbed balance between cell proliferation and apoptosis. This study addressed the unsolved issue of apoptosis in hyperparathyroidism. METHODS: Parathyroid glands from 19 patients with primary (1 degrees ) and 11 patients with secondary (2 degrees ) uremic hyperparathyroidism, as well as 13 normal parathyroid glands, were examined. Apoptosis was evaluated by terminal deoxynucleotidyl transferase (Tdt)-mediated dUTP nick end-labeling assay (TUNEL). Because the apoptotic process is regulated by several oncoproteins, the expression of Bcl-2 and Bax was analyzed by immunohistochemistry. RESULTS: The numbers of apoptotic cells in 1 degrees parathyroid adenoma (0.99 +/- 0.03 per 1000 cells, mean +/- SE, P < 0.009) and 2 degrees parathyroid hyperplasia (1.20 +/- 0.54 per 1000 cells, P < 0.005) were significantly higher than in normal parathyroid tissue (0.13 +/- 0. 06 per 1000 cells). Light microscopy examination of hyperplastic parathyroid tissue from a uremic patient showed the presence of nuclei with dense chromatin characteristic of apoptosis. Bcl-2 staining was strong in normal tissues but weak or negative in several sections of 1 degrees and 2 degrees hyperparathyroid tissues, mostly in nodular areas. Bax staining was homogeneous in normal tissue but patchy in several hyperplastic tissues. CONCLUSION: These results suggest that hyperparathyroidism is associated with a compensatory increase in apoptosis, possibly favored by a diminished Bcl-2/Bax ratio. This renders highly improbable the hypothesis that parathyroid hyperplasia is due to a decreased rate of apoptosis.     

Noninvasive parathyroid imaging in primary hyperparathyroidism

Several studies suggested that preoperative localization of abnormal parathyroid (PT) glands may be useful in reducing operative time facilitating parathyroidectomy, especially in patients with ectopic PT glands. At present, noninvasive techniques used to evaluate patients with primary HPT include (1) 99mTc-sestamibi scintigraphy, (2) high-resolution neck ultrasonography, (3) CT scanning, and (4) magnetic resonance imaging (MRI). The sensitivity and positive predictive value of each technique range from 70% to 90%, and a combination of two of more tests may significantly improve the results. In the minimally-invasive era both radioguided and video-assisted parathyroidectomy require an accurate preoperative localization of the abnormal PT glands, and PT imaging should be obtained before surgery in all patients with primary hyperparathyroidism, with the aim of reducing operative time and hospital stay.