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At least 19 recordsLinked to original sources

PubMed2002

Radiosurgery for residual or recurrent nonfunctioning pituitary adenoma.

OBJECT: Nonfunctioning pituitary adenomas comprise approximately 30% of all pituitary tumors. The purpose of this retrospective study is to evaluate the efficacy and role of gamma knife radiosurgery (GKS) in the management of residual or recurrent nonfunctioning pituitary adenomas. METHODS: A review was conducted of the data obtained in 42 patients who underwent adjuvant GKS at the University of Pittsburgh between 1987 and 2001. Prior treatments included transsphenoidal resection, craniotomy and resection, or conventional radiotherapy. Endocrinological, ophthalmological, and radiological responses were evaluated. The duration of follow-up review varied from 6 to 102 months (mean 31.2 months). Fifteen patients were observed for more than 40 months. The mean radiation dose to the tumor margin was 16 Gy. Conformal radiosurgery planning was used to restrict the dose to the optic nerve and chiasm. Tumor control after GKS was achieved in 100% of patients with microadenomas and 97% of patients with macroadenomas. Gamma knife radiosurgery was equally effective in controlling adenomas with cavernous sinus invasion and suprasellar extension. No patient developed a new endocrinological deficiency following GKS. One patient's tumor enlarged with an associated decline in visual function. Another patient experienced a deterioration of visual fields despite a decrease in tumor size. CONCLUSIONS: Gamma knife radiosurgery can achieve tumor control in virtually all residual or recurrent nonfunctioning pituitary adenomas. Dose sparing facilitates tumor management even when the adenoma is close to the optic apparatus or invades the cavernous sinus.

Adenoma↗

PubMed2000

Gamma knife radiosurgery as a primary treatment for prolactinomas.

OBJECT: The purpose of this study was to estimate the efficacy of gamma knife radiosurgery (GKS) in controlling tumor growth and endocrinopathy associated with prolactinomas. METHODS: Between 1993 and 1997, 164 of 469 patients with pituitary adenomas treated by GKS harbored prolactinomas. The dose to the tumor margin ranged from 9 to 35 Gy (mean 31.2 Gy), and the visual pathways were exposed to a dose of less than 10 Gy. The mean tumor diameter was 13.4 mm. The mean follow-up time for 128 cases was 33.2 months (range 6-72 months). Tumor control was observed in all but two patients who underwent surgery 18 and 36 months, respectively, after GKS. Clinical cure was achieved in 67 cases. Clinical improvement was noted with a decrease in the hyperprolactinemia after GKS. Nonetheless, in 31 (29%) of 108 patients who were followed for more than 2 years no improvement in serum prolactin levels was demonstrated, although this could be normalized by bromocriptine administration after treatment. Nine infertile women became pregnant 2 to 13 months after GKS and all gave birth to normal children. There was no visual deterioration related to GKS. Five women experienced premature menopause. In these patients there was subtotal disappearance of the tumor and an empty sella developed. CONCLUSIONS: Gamma knife radiosurgery as a primary treatment for prolactinomas can be safe and effective both for controlling tumor growth and for normalization of prolactin hypersecretion. A higher margin dose (> or = 30 Gy) seemed to be associated with a better clinical outcome. Gamma knife radiosurgery may make prolactinomas more sensitive to the bromocriptine.

Humans↗

PubMed1999

Needle-knife fistulotomy versus needle-knife precut papillotomy for the treatment of common bile duct stones.

BACKGROUND: The aim of this prospective study was to evaluate and compare the efficacy and safety of two different precutting techniques in the treatment of 103 consecutive patients with choledocholithiasis. METHODS: The patients were randomized into two groups. The first group included 74 patients who underwent needle-knife fistulotomy avoiding the papillary orifice followed by standard papillotomy. Fifty-two of these patients had a final diagnosis of choledocholithiasis. The second group included 79 patients who underwent needle-knife precut papillotomy starting from the papillary orifice followed by standard papillotomy. Fifty-one of these patients had a final diagnosis of choledocholithiasis. RESULTS: Precutting was successful in 90.54% of patients in the needle-knife fistulotomy group and 88.6% of patients in the needle-knife precut papillotomy group. Stone extraction without mechanical lithotripsy was achieved in 40 of 48 (83.33%) patients in the needle-knife fistulotomy group and 45 of 46 (97.82%) patients in the needle-knife precut papillotomy group (p < 0.05). For the other patients, stone extraction was achieved with the aid of a mechanical lithotriptor. Complications were as follows for the needle-knife fistulotomy and needle-knife precut papillotomy groups, respectively: bleeding, 6.75% and 5.06%; perforation, 2.7% and 2. 53%; cholangitis, 1.35% and 0; pancreatitis, 0 and 7.59% (p < 0.05); hyperamylasemia, 2.7% and 17.72% (p < 0.01); and death, 0 and 1.26%. CONCLUSIONS: Both methods are effective in the management of choledocholithiasis. When needle-knife fistulotomy is performed, however, lithotripsy is needed more often. Needle-knife fistulotomy is safer than needle-knife precut papillotomy with respect to pancreatic complications.

Adult↗

PubMedDate not supplied

The influence of knife dullness on poultry processing operator exertions and the effectiveness of periodic knife steeling.

A novel procedure is described to establish knife steeling schedules for poultry and meat- processing operations based on increased force due to knife dullness from repetitive use to minimize operator exertions and physical stress associated with work-related musculoskeletal disorders. Knife dullness was quantified using a novel apparatus described in this article that measures the area cut by a knife into a carrageenan gel target for a controlled dynamic load at the knife handle. Two meat-cleaning jobs in a poultry-processing plant were studied. One job required significantly more force and a greater number of cuts than the other. Eight experienced operators participated in the study. Four freshly ground and honed knives were randomly used by each operator for 4, 45, 75, or 125 cutting cycles, measured for dullness and reconditioned by the operator using a steel sharpening rod. An empirical model for knife dulling and reconditioning was developed, and the corresponding increase in force was predicted for various cutting and reconditioning frequencies. The model showed that it took 57 and 125 cutting cycles for the high- and low-force jobs, respectively, to achieve a similar reduction in target surface area of 30%. This reduction in target surface area corresponded to a similar percentage increase in force needed for the same cut in carrageenan gel as compared to a freshly honed knife as measured using strain gages. This method may be used in meat processing plants for determining effective reconditioning schedules that reduce operator exertions with minimum effect on quality and productivity.

Adult↗

PubMed1996

A comparison of craniotomy and Gamma Knife charges in a community-based Gamma Knife Center.

The hospital charges for all craniotomies and transsphenoidal procedures were gathered for a 4-year period from a single, non-profit hospital serving San Diego. Calif., USA. Of the individuals in this community 65% are covered by a variety of managed health care programs which have greatly discounted hospital receipts on a per diem or capitated payment basis. A total of 104 operative cases were identified. Forty-six patients (44%) were judged to have been eligible for Gamma Knife surgery. The average hospital charge for intracranial surgery on Gamma-Knife-eligible individuals was 14% greater than the nominal Gamma Knife surgery charge would have been. The complication rate for treated Gamma-Knife-eligible individuals was 15% including blindness in one eye after removal of a tuberculum sella meningioma, and hemiplegia following a delayed postoperative hemorrhage after arteriovenous malformation resection in another patient. Actual hospital net receipts were 55% of charges and probably approached the true hospital cost per procedure. When these hospital receipts were compared to the estimated cost per procedure of Gamma-Knife surgery, Gamma Knife surgery had a 30% cost advantage over surgical resection.

California↗

PubMed1999

Stereotactic radiosurgery, X: clinical isodosimetry of gamma knife versus linear accelerator X-knife for pituitary and acoustic tumours.

Several review articles have compared gamma unit versus linear accelerator (linac)-based radiosurgery systems, concluding that the dose gradient 'fall-off' at the margin of the target (expressed as the distance between isodoses) is very similar for both techniques as far as single isocentre treatment volumes up to 1.5 cm diameter are concerned, and that the two radiosurgical systems are, in general, comparable. 'Fine tuning' of the gamma unit can be carried out by using multiple isocentre plans, the differential use of small collimator sizes (down to 4 mm) and field weightings, and adroit use of the gamma angle, and selective beam blocking. Multiple isocentre plans, beam modification, restriction of gantry angles and arc lengths, and microcollimation can similarly improve the isodose gradients from linac units. In both instances, the dosimetric advantages occur along selected aspects of the target perimeter border. However, the more frequent use of multiple isocentred 'shots' on the gamma unit achieves greater conformity indices for more complex target volumes, but at the expense of steeper internal dose gradients. We studied two patients with tumours close to or arising from radiosensitive special sensory nerves (optic and cochlear) to compare and contrast fine tuning of the two technologies. In a previously irradiated patient with a pituitary adenoma, the dose gradient achieved at the rostral margin, adjacent to the optic chiasma, was steeper on the gamma unit (due to the concentration of small collimator shots rostrally and beam blocking), which was therefore the dosimetrically preferred technique. In contrast, the vastly smaller internal dose gradient (11% for linac/X-knife versus 100% for Gamma Knife) and the ability to fractionate on the X-knife system, gave a large dosimetric advantage to the X-knife plan in the treatment of an acoustic neuroma, where the intracanalicular component of the cochlear nerve traversed the target volume. This advantage also pertains to the cochlear ramus of the internal auditory (labyrinthine) artery and the facial nerve. Our published work on X-knife radiosurgery of acoustic neuroma has documented improvement of hearing after therapy and may be relevant in this regard. That there are advantages in physical dose distribution and fractionation, producing a reduction in the biological dose in normal tissue, argues for the use of linac technology in acoustic neuromas. Craniopharyngiomas enveloping the optic nerve/chiasma will similarly be better treated by the linac X-knife system. It is apparent that different radiosurgery systems may be indicated in particular neuro-oncological situations.

Adenoma↗

PubMed1998

Gamma knife radiosurgery for pituitary adenomas: usefulness of combined transsphenoidal and gamma knife radiosurgery for adenomas invading the cavernous sinus.

Thirty-seven of 317 patients with pituitary adenoma who underwent transsphenoidal operation from 1989 to 1996 received adjuvant gamma knife radiosurgery. Gamma knife surgery was performed mainly in patients with endocrinologically inactive tumor for tumor regrowth invading the cavernous sinus, and in patients with endocrinologically active tumor for incomplete removal invading the cavernous sinus. The maximum radiation dose was 25-60 Gy. The periphery of the tumor usually received 50% of the maximum dose. Thirteen patients were followed up for longer than 2 years (mean 45 months) after combined therapy. Magnetic resonance imaging (MRI) showed changes in signal intensity on both T1- and T2-weighted images as early as 3 months after radiotherapy. Serial MRI showed all 13 patients had achieved excellent response. Patients with endocrinologically active tumors showed normalized hormone levels 24 months after gamma knife surgery except for one patient with acromegaly. The basal value of pituitary hormones remained normal during the follow-up period, and four female patients became pregnant without hormonal therapy. Combined transsphenoidal surgery and gamma knife radiosurgery can preserve normal pituitary function and eradicate adenoma invading the cavernous sinus.

Adenoma↗

PubMedDate not supplied

A study of the optical micrometer, the coin gauge, and the diamond knife micrometer in diamond knife calibration.

Reproducible results in refractive keratectomy are greatly influenced by an accurate setting of the diamond knife blade length. In this study, we evaluated the accuracy and reproducibility of three existing techniques of blade calibration: the KOI coin gauge, the KOI diamond knife handle micrometer, and the Magnum optical micrometer. Serial blade length measurements of three similarly designed KOI diamond knives were made using each of the above calibration methods. The three knife handle micrometers had the largest measurement error (3.55%, 2.83%, 1.82%), and therefore the sole reliance of the handle micrometer for blade calibration was not recommended. The measurements made by the coin gauge on the three knives had measurement errors of 1.03%, 1.64%, and 1.46%. The optical micrometer achieved an accuracy of 0.005 mm and an interobserver precision of 0.009 mm. We prefer using the optical micrometer because the potential for parallax error is eliminated; it has a lower risk of blade damage; it is easier to use; and it also allows detection of defects in the footplates, the diamond knife, and of the wobbling blade, which may contribute to calibration error.

Calibration↗

PubMed2003

Wounding patterns and human performance in knife attacks: optimising the protection provided by knife-resistant body armour.

BACKGROUND: Stab attacks generate high loads, and to defeat them, armour needs to be of a certain thickness and stiffness. Slash attacks produce much lower loads and armour designed to defeat them can be far lighter and more flexible. METHODS AND SUBJECTS: Phase 1: Human performance in slash attacks: 87 randomly selected students at the Royal Military College of Science were asked to make one slash attack with an instrumented blade on a vertically mounted target. No instructions on how to slash the target were given. The direction, contact forces and velocity of each attack were recorded. Phase 2: Clinical experience with edged weapon attacks: The location and severity of all penetrating injuries in patients attending the Glasgow Royal Infirmary between 1993 and 1996 were charted on anatomical figures. RESULTS: Phase 1: Two types of human slash behaviour were evident: a 'chop and drag' blow and a 'sweep motion' type of attack. 'Chop and drag' attacks had higher peak forces and velocities than sweep attacks. Shoulder to waist blows (diagonal) accounted for 82% of attacks, 71% of attackers used a long diagonal slash with an average cut length of 34 cm and 11% used short diagonal attacks with an average cut length of 25 cm. Only 18% of attackers slashed across the body (short horizontal); the average measured cut length of this type was 28 cm. The maximum peak force for the total sample population was 212 N; the maximum velocity was 14.88 m s(-1). The 95 percentile force for the total sample population was 181 N and the velocity was 9.89 m s(-1). Phase 2: 431 of the 500 patients had been wounded with edged weapons. The average number of wounds sustained by victims in knife assaults was 2.4. The distribution of wounds by frequency and severity are presented. CONCLUSIONS: Anti-slash protection is required for the arms, neck, shoulders, and thighs. The clinical experience of knife-attack victims provides information on the relative vulnerabilities of different regions of the body. It is anticipated that designing a tunic-type of Police uniform that is inherently stab and slash resistant will eventually replace the current obvious and often bulky extra protective vest. Attempts at making a combined garment will need to be guided by ergonomic considerations and field testing. A similar anatomical regional risk model might also be appropriate in the design of anti-ballistic armour and combined anti-ballistic and knife-resistant armour.

Journal Article↗

PubMed2004

Souvenir knife: a retained transcranial knife blade.

Upon necroscopic examination of a homeless male found comatose in the street and pronounced dead at a medical center 12 hours later, a sharp tip of a knife lodged in the right parietal region of his skull was incidentally discovered. The blade transected the diploe and penetrated the cerebral cortex. Subsequent police investigation revealed that this was the remnant of a stabbing attempt on his life several months prior to his death. The cause of death was determined to be unrelated to the metallic blade fragment, thus making it a truly incidental and rare finding of a "souvenir knife." Nevertheless, since the injury sustained in the stabbing was potentially life threatening, the investigation into that assault was reopened.A case report is presented, along with a brief review of the literature on "souvenir objects."

Foreign Bodies↗

PubMed1997

Gamma Knife radiosurgery: indications, techniques, and results in 200 patients treated at the Midwest Gamma Knife Center.

During radiosurgery, a single high dose of ionizing radiation is delivered with exquisite precision to a radiographically defined intracranial target. More than 60,000 patients have been treated worldwide since the first Gamma Knife was installed in Stockholm in 1968. Indications include arteriovenous malformation, cerebral metastasis, acoustic neuroma, meningioma, malignant glioma, and trigeminal neuralgia. Two hundred patients have been treated at the Midwest Gamma Knife Center in the first 21 months of operation beginning in September 1994.

Arteriovenous Malformations↗

PubMed2000

A comparison of microbipolar cautery dissection to hot knife and cold knife cautery tonsillectomy.

BACKGROUND: Morbidity following tonsillectomy continues to be a major concern to parents, children, and physicians alike. Reduction in post-operative complications, optimal control of pain, and satisfactory return to a normal lifestyle are all important to both family and society. This study compares both the complication and recovery rates after microbipolar dissection (MBPD) technique of tonsillectomy to two well established tonsillectomy techniques: hot knife (HK) and cold knife/cautery (CK/C). METHODS: A total of 200 consecutive patients presenting for tonsillectomy by the first author (MP) were randomized to either undergo MBPD or HK tonsillectomy. Concurrently, an additional two hundred patients were randomized to undergo MBPD or CK/C tonsillectomy by the second author (LB). Patients were prospectively followed for complications including bleeding and dehydration and multiple indicators of recovery rate. RESULTS: Postoperative bleeding of any kind was significantly less in the MBPD group than in the CK/C and HK groups (5 vs 12.4 vs 12.5% (P<0.001). The need for post-operative intervention for bleeding, i.e. local control or return to the operating room, was also significantly less in the MBPD group. Return to normal activity occurred 2 days earlier in the MBPD group versus either CK/C or HK (P<0.001). Additionally, earlier recovery was reflected in fewer total doses of pain medication in the MBPD group. Operative time was 3-5 min longer for MBPD (24.2 min) than for CK/C or HK (21.1 and 16.5 min, respectively); blood loss was similar (within 15 cc) among all treatment groups. CONCLUSION: MBPD tonsillectomy compared most favorably to conventional techniques (CK/C and to HK tonsillectomy). Important clinical outcome differences included a lower bleed rate, earlier recovery and fewer days lost from work and school. The financial impact is estimated to be quite favorable. MBPD tonsillectomy is now our preferred method in children.

Adolescent↗

PubMed1999

Gamma Knife radiosurgery for metastatic brain tumor: the usefulness of repeated Gamma Knife radiosurgery for recurrent cases.

Forty-one patients with a total of 193 metastatic brain tumors were treated because of new lesions or in a few cases because of tumor regrowth. The management involved two to four treatments with Gamma Knife radiosurgery (GKRS). The overall median survival was 15 months. The local control rate of tumors was 89% for the first treatment and 93% for repeated treatments. Symptomatic radiation-induced edema appeared in only two cases (4.9%). Patients with metastatic brain tumors who developed new lesions after GKRS were treated with GKRS alone for subsequent lesions. It was possible to control tumors for a long period with minimal side effects. As a result, we were able to maintain the quality of life of these patients, but, the effect of GKRS in controlling tumor regrowth seemed temporary.

Actuarial Analysis↗

PubMed2002