Resection of suprasellar tumors by using a modified transsphenoidal approach. Report of four cases

Generally accepted contraindications to using a transsphenoidal approach for resection of tumors that arise in or extend into the suprasellar region include a normal-sized sella turcica, normal pituitary function, and adherence of tumor to vital intracranial structures. Thus, the transsphenoidal approach has traditionally been restricted to the removal of tumors involving the pituitary fossa and, occasionally, to suprasellar extensions of such tumors if the sella is enlarged. However, conventional transcranial approaches to the suprasellar region require significant brain retraction and offer limited visualization of contralateral tumor extension and the interface between the tumor and adjacent structures, such as the hypothalamus, third ventricle, optic apparatus, and major arteries. In this paper the authors describe successful removal of suprasellar tumors by using a modified transsphenoidal approach that circumvents some of the traditional contraindications to transsphenoidal surgery, while avoiding some of the disadvantages of transcranial surgery. Four patients harbored tumors (two craniopharyngiomas and two hemangioblastomas) that arose in the suprasellar region and were located either entirely (three patients) or primarily (one patient) within the suprasellar space. All patients had a normal-sized sella turcica. Preoperatively, three of the four patients had significant endocrinological deficits signifying involvement of the hypothalamus, pituitary stalk, or pituitary gland. Two patients exhibited preoperative visual field defects. For tumor excision, a recently described modification of the traditional transsphenoidal approach was used. Using this modification, one removes the posterior portion of the planum sphenoidale, allowing access to the suprasellar region. Total resection of tumor was achieved (including absence of residual tumor on follow-up imaging) in three of the four patients. In the remaining patient, total removal was not possible because of adherence of tumor to the hypothalamus and midbrain. One postoperative cerebrospinal fluid leak occurred. Postoperative endocrinological function was worse than preoperative function in one patient. No other new postoperative endocrinological or neurological deficits were encountered. This study demonstrates the feasibility of using a modified transsphenoidal approach for resection of certain suprasellar, nonpituitary tumors.

Neuroprotection by the stable nitroxide Tempol during reperfusion in a rat model of transient focal ischemia

OBJECT

The use of thrombolytic agents in the treatment of stroke has yielded surprisingly modest success, possibly because of reperfusion injury mediated by reactive oxygen species (ROS). Therefore, scavenging ROS may be of therapeutic value in the treatment of stroke. Nitroxides are low-weight superoxide dismutase mimics, which allows them to act as cell-permeable antioxidants. In this study the nitroxide 4-hydroxy-2,2,6,6,-tetramethylpiperidine-1-oxyl (Tempol) is investigated to determine its ability to reduce reperfusion injury.

METHODS

Male Sprague-Dawley rats weighing between 280 g and 350 g underwent middle cerebral artery occlusion with an intraluminal suture for 60 minutes. Regional cerebral blood flow, blood pressure, cerebral temperature, and rectal temperature were monitored during the procedure. After reperfusion, the animals were randomized to groups receiving blinded intravenous administration of either Tempol (10 mg/kg; eight animals) or vehicle (eight animals) over the first 20 minutes of reperfusion (Study I). In a second study to determine dose dependency, animals were randomized to groups receiving Tempol (20 mg/kg; eight animals), low-dose Tempol (5 mg/kg; eight animals), or vehicle (eight animals; Study II). The rats were killed after 4 hours of reperfusion, and brain sections were stained with 2,3,5 triphenyltetrazolium chloride. Infarct volumes were measured using digital imaging. Animals receiving Tempol had significantly reduced infarct volumes at doses of 20 mg/kg and 10 mg/kg compared with controls (49.01+/-18.22% reduction [p = 0.003] and 47.47+/-34.57 [p = 0.02], respectively). No significant differences in the physiological variables measured were observed between groups.

CONCLUSIONS

Tempol provides significant neuroprotection after reperfusion in a rat model of transient focal ischemia. These results support the importance of ROS in reperfusion injury and encourage further study of this molecule as a therapeutic agent following thrombolysis.

Neurosurgical implications of Carney complex

OBJECT

The authors present their neurosurgical experience with Carney complex. Carney complex, characterized by spotty skin pigmentation, cardiac myxomas, primary pigmented nodular adrenocortical disease, pituitary tumors, and nerve sheath tumors (NSTs), is a recently described, rare, autosomal-dominant familial syndrome that is relatively unknown to neurosurgeons. Neurosurgery is required to treat pituitary adenomas and a rare NST, the psammomatous melanotic schwannoma (PMS), in patients with Carney complex. Cushing's syndrome, a common component of the complex, is caused by primary pigmented nodular adrenocortical disease and is not secondary to an adrenocorticotropic hormone-secreting pituitary adenoma.

METHODS

The authors reviewed 14 cases of Carney complex, five from the literature and nine from their own experience. Of the 14 pituitary adenomas recognized in association with Carney complex, 12 developed growth hormone (GH) hypersecretion (producing gigantism in two patients and acromegaly in 10), and results of immunohistochemical studies in one of the other two were positive for GH. The association of PMSs with Carney complex was established in 1990. Of the reported tumors, 28% were associated with spinal nerve sheaths. The spinal tumors occurred in adults (mean age 32 years, range 18-49 years) who presented with pain and radiculopathy. These NSTs may be malignant (10%) and, as with the cardiac myxomas, are associated with significant rates of morbidity and mortality.

CONCLUSIONS

Because of the surgical comorbidity associated with cardiac myxoma and/or Cushing's syndrome, recognition of Carney complex has important implications for perisurgical patient management and family screening. Study of the genetics of Carney complex and of the biological abnormalities associated with the tumors may provide insight into the general pathobiological abnormalities associated with the tumors may provide insight into the general pathobiological features of pituitary adenomas and NSTs.

Alliance ruptures and repairs in experiential therapy

The formation and maintenance of a positive working alliance is fundamental to the success of experiential therapy. Experiential therapists face a special challenge insofar as they must constantly consider whether to direct the therapeutic process more actively or remain more closely within the clients' own frame of reference. This requires that experiential therapists be acutely aware of the alliance with their clients on a moment-to-moment basis during the session. In this article ruptures to the alliance, comprising breakdowns In the agreement between clients and therapists as to the goals and tasks of therapy during the early and middle phases of treatment, are identified and explored. As ruptures are often covert processes, methods of detecting their occurrence during the session are presented. Finally, experiential techniques for forging, maintaining, and repairing the alliance between clients and therapists are discussed and illustrated.

Importance of timing and length of administration of angiogenesis inhibitor TNP-470 in the treatment of K12/TRb colorectal hepatic metastases in BD-IX rats

BACKGROUND

The timing and length of administration of angiogenesis inhibitor TNP-470 was altered to evaluate the effect on disease progression in a rat model of colorectal hepatic metastases.

METHODS

Pair-fed BD-IX rats, injected intrasplenically with rat colon adenocarcinoma K12/TRb cells at day 0, were randomized to receive subcutaneous injections of either placebo or 15 mg/kg TNP-470 on alternate days: for 2 weeks beginning 24 hours after tumor inoculation ("Early"), for 4 weeks beginning 24 hours after tumor inoculation ("Prolonged"), or for 2 weeks beginning at day 15 after macroscopic tumor nodules were confirmed ("Delayed"). Response to treatment was evaluated by counting tumor nodules on the surface of the liver at laparotomy on day 14 and 28 after tumor inoculation. The animals were followed for survival and cause of death.

RESULTS

Maximal suppression of hepatic metastases at day 28 required 4-week rather than 2-week TNP-470 administration. Prolonged TNP-470 administration resulted in significantly fewer hepatic metastases at day 28 compared to control (P < .05). Early and prolonged TNP-470 improved survival (Wilcoxon test, P < .05) compared with delayed TNP-470 and placebo. Delayed TNP-470 administration did not increase survival or significantly diminish the number of metastases at day 28 compared with placebo.

CONCLUSIONS

These data suggest that prolonged adjuvant antiangiogenic therapy may suppress colorectal hepatic micrometastases.

Importance of timing and length of administration of angiogenesis inhibitor TNP-470 in the treatment of K12/TRb colorectal hepatic metastases in BD-IX rats

BACKGROUND

The timing and length of administration of angiogenesis inhibitor TNP-470 was altered to evaluate the effect on disease progression in a rat model of colorectal hepatic metastases.

METHODS

Pair-fed BD-IX rats, injected intrasplenically with rat colon adenocarcinoma K12/TRb cells at day 0, were randomized to receive subcutaneous injections of either placebo or 15 mg/kg TNP-470 on alternate days: for 2 weeks beginning 24 hours after tumor inoculation ("Early"), for 4 weeks beginning 24 hours after tumor inoculation ("Prolonged"), or for 2 weeks beginning at day 15 after macroscopic tumor nodules were confirmed ("Delayed"). Response to treatment was evaluated by counting tumor nodules on the surface of the liver at laparotomy on day 14 and 28 after tumor inoculation. The animals were followed for survival and cause of death.

RESULTS

Maximal suppression of hepatic metastases at day 28 required 4-week rather than 2-week TNP-470 administration. Prolonged TNP-470 administration resulted in significantly fewer hepatic metastases at day 28 compared to control (P < .05). Early and prolonged TNP-470 improved survival (Wilcoxon test, P < .05) compared with delayed TNP-470 and placebo. Delayed TNP-470 administration did not increase survival or significantly diminish the number of metastases at day 28 compared with placebo.

CONCLUSIONS

These data suggest that prolonged adjuvant antiangiogenic therapy may suppress colorectal hepatic micrometastases.

Extrapituitary parasellar microadenoma in Cushing's disease

Negative sellar exploration (despite the results of endocrine evaluation indicating Cushing's disease), the high incidence of failure of total hypophysectomy, and remission of Cushing's syndrome after unsuccessful hypophysectomy and sellar irradiation suggest that the etiology of refractory Cushing's disease, in some patients, lies near the sella but not in the pituitary gland. We present 5 patients, out of 626 who received surgery for Cushing's disease, in whom an ACTH-secreting extrapituitary parasellar adenoma was identified: 2 after unsuccessful total hypophysectomy for the treatment of refractory Cushing's disease, 2 after unsuccessful hemihypophysectomy (the first, 2 yr before treatment at the NIH for Nelson's syndrome; and the second, with recurrent Cushing's disease 5 yr after negative transsphenoidal exploration), and 1 with a preoperative diagnosis of an intraclival microadenoma, which was cured by resection of the tumor. In all cases, an extrapituitary parasellar microadenoma was confirmed unequivocally as the cause of the disease, by negative pathology of the resected pituitary gland (patients 1, 2, 3, and 5), and/or the remission of the disease after selective resection of the extrasellar adenoma (patients 3, 4, and 5). Three of 5 patients had a partial empty sella. These patients support the thesis that ACTH-secreting tumors can arise exclusively from remnants of Rathke's pouch, rather than from the adenohypophysis (anterior lobe or pars tuberalis of the pituitary gland) and can be a cause of Cushing's disease. In the sixth presented case, an extrapituitary tumor was suspected at surgery after negative pituitary exploration, but serial sections of the hemihypophysectomy specimen revealed a microscopic focus of tumor at the margin of the resected gland. This case demonstrates the importance of negative pituitary histology to establish the presence of an extrapituitary parasellar tumor as an exclusive source of ACTH, and it supports the value of clinical outcome to establish the diagnosis with selective adenomectomy of an extrapituitary parasellar tumor. In patients with negative pituitary magnetic resonance imaging, especially in the presence of a partial empty sella, the diagnostic and surgical approach in Cushing's disease should consider the identification and resection of extrapituitary parasellar adenoma, which can avoid total hypophysectomy, as was possible in 3 of our 5 patients.

Intraoperative gamma detection of 125I-lanreotide in women with primary breast cancer

BACKGROUND

Somatostatin receptors are present in most human breast cancers. We performed a pilot trial of intraoperative tumor-gamma detection using the radiolabeled somatostatin analog 125I-lanreotide in 13 women with 14 primary breast carcinomas.

METHODS

All patients were given 125I-lanreotide intravenously before surgery. Patients underwent lumpectomy, and postresection margins were evaluated with the gamma probe. Axillary dissection specimens were evaluated ex vivo.

RESULTS

Seven of 13 women had gamma probe-positive or clinically suspicious margins re-excised at the time of lumpectomy. Four of six probe-positive margins were histologically positive, and two of six probe-positive margins were histologically negative; a single clinically suspicious margin was histologically positive. A total of 270 axillary lymph nodes were evaluated ex vivo by gamma probe and histology. McNemar's contingency tests demonstrated a highly statistical correlation between histology and gamma probe counts (P < .0001).

CONCLUSIONS

The overall accuracy of nodal evaluation with 125I-lanreotide/intraoperative gamma detection was 77%; the negative predictive value of this technique was 97%, however. This technique predicted the presence of tumor in 20% of axillary lymph nodes that were negative by routine histology. This technique appears safe and is able to detect positive tumor resection margins and accurately predict axillary lymph node negativity. Further trials of this technique are required to validate its utility.

Vascular endothelial growth factor is a marker of tumor invasion and metastasis in squamous cell carcinomas of the head and neck

Angiogenesis has been linked to increased metastasis formation and decreased overall survival in patients with various tumors, including and neck squamous cell carcinomas (HNSCC). Vascular endothelial growth factor (VEGF) is a key regulator of angiogenesis. In the present study, we evaluated VEGF expression and microvessel density (MVD), a quantitative means of angiogenesis, in both experimental and clinical models of HNSCC. Analysis of VEGF RNA expression in cell lines of keratinocyte origin [HNSCC, facial skin squamous cell carcinoma (SCC), and transformed but nontumorigenic keratinocytes] and normal skin keratinocytes revealed two VEGF transcripts corresponding to proteins of 165 and 121 amino acids in length, with the transcript for the 165-amino acid species predominating. Six of eight SCC cell lines showed increased levels of one or both transcripts, and seven SCC cell lines and the transformed keratinocyte cell line showed increased protein expression. We then evaluated VEGF protein expression in human head and neck specimens containing normal epithelium (n = 10), dysplasia or carcinoma in situ (CIS; n = 15), early invasive SCCs (n = 9), advanced primary SCCs (n = 10), lymph node metastases (n = 3), and s.c. tumors or cysts (n = 7) formed in severe combined immunodeficient mice. Intense VEGF staining was found in the majority of advanced primary SCCs, lymph node metastases, and human SCCs in severe combined immunodeficient mice, whereas no dysplasia, CIS, or early SCCs showed intense immunostain. A highly significant increase (P = 0.0001) in VEGF expression was seen in the advanced SCC versus dysplasias and CIS lesions, as was the difference between SCC versus normal epithelium from nonsmokers (P = 0.01). VEGF expression in advanced primary cancers was greater (P = 0.002) and, in early cancers, marginally greater (P = 0.05) than adjacent normal mucosa. MVD increased with the progression of preinvasive disease (P = 0.04). VEGF expression and MVD (both, P = 0.003) were directly associated with tumor aggressiveness in experimental tumors. These findings suggest a role for VEGF in both clinical and experimental HNSCC.

The surgical management of spinal dural vascular malformations

Spinal dural arteriovenous fistulas (AVFs) are the most common spinal vascular malformation. The spinal dural AVF is a disease of adults, primarily men, that is a cause of subacute progressive lower extremity myelopathy. The challenge for the optimum management of these patients is in making an accurate, early diagnosis. Definitive surgical intervention by interruption of the intradural draining vein is the treatment of choice.

True fungal mycotic aneurysm of the basilar artery: a clinical and surgical dilemma

Mycotic aneurysms of the intracranial circulation of true fungal etiology are extremely rare and are associated with a very high mortality. We report a case of a fatal aneurysm of the basilar artery secondary to Scedosporium apiospermum infection. The medical and surgical treatments are presented to demonstrate the difficulties associated with these lesions.

Photoregulated expression of the PsPK3 and PsPK5 genes in pea seedlings

The PsPK3 and PsPK5 genes of the garden pea encode protein-serine/threonine kinases whose catalytic domains are closely related to known signal transducing kinases from animals and fungi. The PsPK3 polypeptide is predicted to be located in the nucleus, whereas PsPK5 is a homologue of NPH1, the probable blue light receptor for phototropism from Arabidopsis. We found previously that when etiolated pea seedlings are illuminated with continuous white light, PsPK3 and PsPK5 transcript levels within apical buds decline substantially, reaching their minimum levels within one day of exposure to light. The role of light in regulating the expression of the PsPK3 and PsPK5 genes was investigated further. To gain insight into the rapidity with which expression changes, 6-day old, dark-grown pea seedlings were transferred to continuous white light, and PsPK3 and PsPK5 RNA levels monitored over the ensuing 24 h. While transcripts from the RbcS gene family increase, the PsPK3 and PsPK5 mRNAs decline rapidly to their minimum levels. PsPK5 mRNA declines 10-fold in ca. 2 h, whereas PsPK3 mRNA declines 4-fold in ca. 8 h. We used single pulses of light to elucidate which photoreceptor triggers the negative regulation of PsPK3 and PsPK5 gene expression. To assess phytochrome involvement, etiolated seedlings were treated with single pulses of red light, red followed by far-red light, or far-red light alone. RbcS induction by a red light pulse is reversible with a subsequent far-red light pulse, clearly showing that phytochrome mediates its induction. Likewise, RbcS expression is induced with a single pulse of blue light or a dichromatic pulse of red+blue light. However, none of these pulses trigger the PsPK3 and PsPK5 mRNA levels to decline. Given the lack of effectiveness of light pulses, etiolated seedlings were transferred to continuous light of three different qualities to determine the spectral sensitivity of PsPK3 and PsPK5 gene expression. Exposure to continuous red, continuous far-red, or continuous blue light causes the PsPK3 and PsPK5 mRNAs to decline and transcripts from the RbcS and Cab gene families to increase. One likely explanation is that phytochrome A mediates the responses of these genes to continuous far-red light. The effectiveness of continuous red light and blue light in triggering the reduction in PsPK3 and PsPK5 mRNA levels and the increase in RbcS and Cab mRNAs may imply the participation of additional phytochromes and/or cryptochromes. Thus, the PsPK3 and PsPK5 genes exhibit responsiveness to continuous light, but a lack of responsiveness to single light pulses that is unusual, and perhaps unique, among light-regulated genes.

Localization of pituitary adenomas by using intraoperative ultrasound in patients with Cushing's disease and no demonstrable pituitary tumor on magnetic resonance imaging

OBJECT

Pituitary surgery has been reported to produce remission of Cushing's disease with preservation of pituitary function in only 60 to 70% of patients. The inability to identify an adenoma accounts for most failed sellar explorations. Most negative surgical explorations occur in patients in whom magnetic resonance (MR) imaging of the pituitary demonstrates normal findings, which happens in at least 35 to 45% of patients with Cushing's disease.

METHODS

To examine the usefulness of intraoperative ultrasonography (IOUS) for identifying an adenoma in patients with no demonstrable tumor (negative findings) on pituitary MR imaging. we prospectively assessed the results of IOUS in 68 patients with a negative (59 patients) or equivocal (nine patients) MR image from a consecutive series of 107 patients with Cushing's disease (64%). We compared surgical findings and outcomes in these 68 patients with a group of 68 patients with Cushing's disease and negative findings on MR imaging in whom IOUS was not available. Intraoperative ultrasonography localized a tumor in 47 (69%) of 68 patients with negative findings on MR imaging. Surprisingly, the size of the adenomas that were detected with IOUS compared with the size of those not detected did not differ (6.8+/-3.4 mm compared with 6.1+/-2.8 mm [mean+/-standard deviation], respectively [p=0.51). In four patients, no adenoma was found at surgery or in the pathological specimen ("true negative"). In eight patients, nine abnormalities detected by IOUS that were suspected adenomas were negative on exploration ("false positive"). Thus, IOUS has a sensitivity of 73% and a positive predictive value of 84% for detecting pituitary adenomas in patients with Cushing's disease and negative findings on MR imaging. Compared with the 68 patients who did not undergo IOUS. remission after surgery was improved (61 patients [90%] compared with 57 patients [84%]), the number of tumors found on exploration was increased (61 tumors compared with 51 tumors, p=0.02), and the number of hemihypophysectomies was decreased (five compared with 15; p=0.02) with IOUS. When the groups were compared after excluding patients with prior pituitary surgery, tumors were found in 91% versus 72% (p=0.008), and remission occurred in 95% versus 87% of patients, respectively, in the groups that had or did not have IOUS.

CONCLUSIONS

The IOUS is a sensitive imaging modality when used in patients with Cushing's disease in whom findings on pituitary MR imaging are negative. The improved ability to detect and localize these tumors by using IOUS positively affects surgical outcome.

Determination of the ischemic threshold for brain oxygen tension

Measuring brain tissue oxygenation is now possible due to major advances in the technical development of Clark-electrodes and fiberoptic systems. However, to make this technique clinically useful for both nurses and medical staff, the ischemic threshold for brain tissue oxygen tension (brain pO2) must be determined. Three end points were used for determination of the critical brain pO2 value. 1) Infarct determination after permanent middle cerebral artery occlusion in a feline model. 2) Threshold analysis using the schemic threshold for cerebral blood flow (CBF) as a "gold standard" in severely head injury patients. 3) Outcome analysis in severely head injured patients. Brain pO2 dropped to 19 +/- 6 mm Hg and 23 +/- 6, 4 to 5 hours after MCA occlusion in the cat (n = 12). In severely head injured patients, a brain pO2 < or = 19 mm Hg was correlated with poor outcome (n = 24). The ischemic threshold for (r)CBF of 18 ml/100 g/min corresponded to a brain pO2 of 22 mm Hg, in the same patients. By using the above mentioned end points as a reference, we found the critical value for brain pO2 to be in between 19 and 23 mm Hg. Clearly, the difference between our threshold value and the lower critical brain pO2 level found by other groups using the Licox system, needs to be clarified in a comparison study before a uniform threshold for brain pO2 can be determined.

Measles, mumps, and rubella--vaccine use and strategies for elimination of measles, rubella, and congenital rubella syndrome and control of mumps: recommendations of the Advisory Committee on Immunization Practices (ACIP)

These revised recommendations of the Advisory Committee on Immunization Practices (ACIP) on measles, mumps, and rubella prevention supersede recommendations published in 1989 and 1990. This statement summarizes the goals and current strategies for measles, rubella, and congenital rubella syndrome (CRS) elimination and for mumps reduction in the United States. Changes from previous recommendations include: Emphasis on the use of combined MMR vaccine for most indications; A change in the recommended age for routine vaccination to 12-15 months for the first dose of MMR, and to 4-6 years for the second dose of MMR; A recommendation that all states take immediate steps to implement a two dose MMR requirement for school entry and any additional measures needed to ensure that all school-aged children are vaccinated with two doses of MMR by 2001; A clarification of the role of serologic screening to determine immunity; A change in the criteria for determining acceptable evidence of rubella immunity; A recommendation that all persons who work in health-care facilities have acceptable evidence of measles and rubella immunity; Changes in the recommended interval between administration of immune globulin and measles vaccination; and Updated information on adverse events and contraindications, particularly for persons with severe HIV infection, persons with a history of egg allergy or gelatin allergy, persons with a history of thrombocytopenia, and persons receiving steroid therapy.

The interruption of transmission of indigenous measles in the United States during 1993

BACKGROUND

The United States has a goal to eliminate all indigenous cases of measles by the year 2000. Initial interruption of indigenous measles transmission would be expected during a period of very low measles incidence as occurred during late 1993.

METHODS

Indigenous measles cases (i.e. cases acquired in the United States and not traceable to any imported case) from 1993 were investigated to determine their source of infection. The probability of sustained undetected measles transmission between isolated indigenous cases was estimated.

RESULTS

Of the 312 measles cases reported for 1993, only 25 (8%) occurred after September 19. Of these only 4 cases (16%) could be classified as indigenous. The estimated probability that any of these 4 cases resulted from indigenous measles transmission in theirs or any adjoining counties was 0.05 or less.

CONCLUSIONS

Interruption of indigenous measles transmission appears to have occurred for the first time throughout the United States in 1993. This event provides strong support for the current national strategy for measles elimination. However, complete elimination of indigenous measles will require maintaining high population immunity to prevent spread from imported cases and attaining global measles control to prevent the importation of measles.

Surgical management of local and regional recurrent head and neck squamous cell carcinoma

During 1997 more than 40,000 Americans developed a squamous cancer of the upper aerodigestive tract. Surgery and radiation therapy may have been used alone or together, with reasonable prospects for curing them of disease. The majority of patients whose cancer cannot be controlled are confronted with local or regional recurrence. Such recurrences often occur in sites of the head and neck that are suited to early detection during an office examination. Hence, many are treatable with curative intent. This review addresses various surgical approaches to these difficult management problems.

Intraoperative monitoring of substrate delivery during aneurysm and hematoma surgery: initial experience in 16 patients

The effects of proximal occlusion of the parent artery during aneurysm surgery in humans are not fully understood, although this method is widely used. The reduction in substrate that can be tolerated by normal and subarachnoid hemorrhage (SAH)-affected brain is unknown. Therefore, the authors measured brain oxygen tension (brain PO2), carbon dioxide tension (brain PCO2), pH, and hemoglobin oxygen (HbO2) saturation before and after temporary occlusion in 12 patients with aneurysms. The effect of removal of a traumatic intracranial hematoma on cerebral oxygenation was also studied in four severely head injured patients. A multiparameter sensor was placed in the cortex of interest and locked by means of a specially designed skull bolt. The mean arterial blood pressure, inspired O2 fraction, and end-tidal PCO2 were analyzed. Brain PO2 and HbO2 saturation data were collected every 10 seconds. Descriptive and nonparametric analyses were used to analyze the data. A wide range in baseline PO2 was seen, although a decrease from baseline in brain PO2 was found in all patients. During temporary occlusion, brain PO2 in patients with unruptured aneurysm (seven patients) dropped significantly, from 60 +/- 31 to 27 +/- 17 mm Hg (p < 0.05). In the SAH group (five patients), the brain PO2 dropped from 106 +/- 74 to 87 +/- 73 mm Hg (not significant). Removal of intracranial hematomas in four severely head injured patients resulted in a significant increase in brain PO2, from 13 +/- 9 to 34 +/- 13 mm Hg (p < 0.05). The duration of safe temporary occlusion could not be determined from this group of patients, because none developed postoperative deterioration in their neurological status. However, the data indicate that this technique is useful to detect changes in substrate delivery during intraoperative maneuvers. This study also reemphasizes the need for emergency removal of intracranial hematomas to improve substrate delivery in severely head injured patients.

The rationale for, and effects of oxygen delivery enhancement to ischemic brain in a feline model of human stroke

Reduced brain tissue oxygenation is frequently seen in severe head injury and after subarachnoid hemorrhage, and this is considered a major cause of secondary ischemic brain injury. In fact, in a previous study, we found a tight correlation between low brain tissue oxygen tension and poor outcome. Therefore, we tested the hypothesis that an allosteric modifier of hemoglobin, which improves oxygen transport to tissue, could reduce the size of an acute infarct in a feline model of human stroke. This compound produces a shift in the hemoglobin dissociation curve to the right and therefore facilitates the unloading of oxygen during low oxygen tension. Seventeen adult cats were studied. Ischemic stroke was induced through a transorbital, permanent, middle cerebral artery occlusion. Seven animals received saline, and 10 received the allosteric Hb modifier RSR-13. Three different endpoints were used to determine the effect of the allosteric modifier. Delta p50 values were measured in the arterial blood; the intra-infarct oxygen tension was measured, and finally, the volume of the infarct was assessed using TTC staining. Mean delta p50 changes varied from 10.4 +/- 9.2 mmHg up to 15.0 +/- 6.8 mmHg. Mean intra-infarct oxygen tension was 27 +/- 6 mmHg for the control group and 33 +/- 7 mmHg for the drug-treated animals. The mean infarct size (measured as percentage of hemisphere volume) in the control group was 32 +/- 9% and for the RSR-13 animals 22 +/- 10% (p < 0.05). A definitive trend towards improvement in brain oxygen tension was seen, such that animals pretreated with RSR-13 showed a higher infarct oxygen tension. Infarct size was significantly reduced in the drug group. Therefore, RSR-13 is potentially beneficial in the treatment of brain ischemia. Since human studies with this compound are already completed, and other compounds which increase oxygen delivery, such as perfluorocarbons, are already being evaluated, it is likely that oxygen delivery enhancement will rapidly become the first 'neuroprotective' modality, employed in patients with severe brain injury, stroke and subarachnoid hemorrhage.

Effects of the allosteric modification of hemoglobin on brain oxygen and infarct size in a feline model of stroke

BACKGROUND AND PURPOSE

Cerebral ischemia and stroke are leading causes of morbidity and mortality. An approach to protecting the brain during ischemia is to try to increase the delivery of oxygen via the residual blood flow through and around ischemic tissue. To test this hypothesis, we used a novel oxygen delivery agent, RSR-13 (2-[4-[[(3,5-dimethylanilino)-carbonyl]-methyl]phenoxy]-2-methylpr opionic acid). Intravenous administration of RSR-13 increases oxygen delivery through allosteric modification of the hemoglobin molecule, resulting in a shift in the hemoglobin/oxygen dissociation curve in favour of oxygen delivery.

METHODS

We studied RSR-13 in a feline model of permanent middle cerebral artery occlusion to assess its effects on cerebral oxygenation and infarct size. A randomized, blinded study of RSR-13 (n = 6) versus 0.45% saline (n = 12) was conducted, after an RSR-13 dose-escalation study (n = 4). Drug was administered as a preocclusion bolus followed by a continuous infusion for the duration of the experiment (5 hours). Brain oxygen was measured continuously with the use of a Clark oxygen electrode. Infarct size was measured at 5 hours after occlusion with computer-assisted volumetric analysis.

RESULTS

The drug treatment group had consistently higher mean brain oxygen tension than controls (33 +/- 5 and 27 +/- 6 mm Hg, respectively) and significantly smaller infarcts (21 +/- 9% versus 33 +/- 9%, respectively, P < .008). We observed an inverse relationship between the dose response of RSR-13 (the shift in the hemoglobin/oxygen dissociation curve) and infarct size.

CONCLUSIONS

These results are evidence that allosteric hemoglobin modification is protective to the brain after acute focal ischemia, providing a new opportunity for neuroprotection and raising the possibility of enhancing the protective effect of thrombolysis and ion channel blockade.

Breast cancer increases initiation of angiogenesis without accelerating neovessel growth rate

BACKGROUND

Recurrence and mortality rates in patients with breast cancer correlate with the degree of tumor angiogenesis (angiogenic index). We have developed a novel angiogenesis model by using disks of fresh human placental vein that initiate an angiogenic response and exhibit linear radial capillary growth in culture. We hypothesized that the addition of human breast cancer cells to this human placental vein angiogenesis model would increase the incidence of angiogenesis and accelerate the rate of neovessel growth compared with vein disk cultured without tumor cells.

METHODS

To test this hypothesis, vein explants from seven human placentas were incorporated into clots of 0.3% fibrin in Medium 199 and fetal bovine serum with or without 1.5 x 10(5) T-47D (n = 6 placentas) or MCF-7 (n = 1 placenta) breast cancer cells. Statistical differences between the experimental (with breast cancer cells) and control (no added cells) cultures were determined by repeated measures ANOVA.

RESULTS

The proportion of disks exhibiting neovessel growth (initiation) by day 12 was significantly increased in the presence of T-47D cells (p < 0.05 at day 12, p < 0.001 at day 15). No statistical difference was seen in rates of neovessel growth (millimeters per day). Similar results were seen with MCF-7 cells.

CONCLUSIONS

Tumor enhancement of angiogenesis may occur by increased initiation of the angiogenic response. Subsequent vessel growth rates may be tumor independent. We predict that effective antiangiogenic therapies will block a tumor's ability to augment angiogenesis initiation rather than subsequent neovessel growth.

Hyperactive pectoralis reflex as an indicator of upper cervical spinal cord compression. Report of 15 cases

Myelopathy from cervical spondylosis is often accompanied by hyperreflexia of the upper-extremity deep tendon reflexes (DTRs). Reflexes such as the pectoralis jerk and the deltoid jerk may only be apparent in the context of hyperreflexia. Although the nerve roots involved in the reflex arcs are well described, levels of cervical spinal cord compression that lead to the hyperreflexia are not as clear. This is of particular significance for patients with multilevel cervical spondylosis in determining the levels responsible for their symptoms. The authors examined 15 consecutive patients who presented for treatment of cervical myelopathy. The clinical examination was then correlated with levels of cervical spinal cord compression by cervical magnetic resonance imaging or computerized tomography with intrathecal contrast enhancement. The presence of a prominent pectoralis jerk was seen only in patients with spinal cord compression at the C2-3 and/or C3-4 levels (nine patients). No patient with compression at or below the C4-5 disc space without coexisting compression at a higher level had hyperactive pectoralis reflexes. This association between the C3-4 level and a hyperactive pectoralis reflex was significant (p < 0.004, Fisher's exact test). The deltoid reflex was tested in the last nine consecutive patients. It was present in patients with compression of the upper spinal cord at levels C3-4 and C4-5 (four of five patients) but appeared in only one of four patients with compression below C4-5. This association did not attain statistical significance. The presence of a hyperactive pectoralis reflex is specific for lesions of the upper cervical spinal cord. Examination of upper-extremity DTRs may be helpful in planning the appropriate levels for surgical decompression in patients with multilevel spondylosis and myelopathy.