The role of nitric oxide in the dorsomedial periaqueductal gray (dmPAG) column in cardiovascular responses in urethane-anesthetized male rats

BACKGROUND

The dorsomedial periaqueductal gray (dmPAG) is a mesencephalic area and has numerous functions including cardiovascular regulation. Because nitric oxide (NO) is present in the dmPAG, here we investigate, the probable cardiovascular effect of NO in the dmPAG.

METHODS

Five groups (n = 6 for each group) were used as follows: (1) control; (2) L-NAME (N^G -nitro-L-arginine methyl ester, a NO synthase inhibitor, 90 nmol); (3) L-arginine (L-Arg, a precursor for NO, 60 nmol); (4) Sodium nitroprusside (SNP, a NO donor, 27 nmol); and (5) L-Arg + L-NAME. The cardiovascular parameters were recorded by a Power Lab device after cannulation of the femoral artery. Drugs were injected using a stereotaxic instrument. The changes (∆) in systolic blood pressure (SBP), mean arterial pressure (MAP), and heart rate (HR) were calculated at different times and compared to the control group.

RESULTS

Microinjection of L-NAME significantly increased ∆SBP, ∆MAP, and ∆HR more than saline (from p < 0.05 to p < 0.001). L-Arg only significantly increased ∆HR (p < 0.05). In the L-Arg + L-NAME group, the above parameters also significantly increased (from p < 0.01 to p < 0.05) but not as significantly as with L-NAME alone. Microinjection of SNP significantly decreased ∆SBP and ∆MAP more than in the control and L-NAME groups (from p < 0.01 to p < 0.001), but ∆HR did not change significantly.

CONCLUSION

The results indicated that NO in dmPAG has an inhibitory effect on cardiovascular responses in anesthetized rats.

Transnasal endoscopic management of frontal sinus mucopyocele with orbital and frontal lobe displacement as minimally invasive surgery

AIM

An obstructive condition of paranasal sinus secondary to surgery, trauma, flogosis or neoplasms could become a predisposing state to the occurrence of mucocele. Frontal sinus mucoceles, which can turn into mucopyoceles due to bacterial super-infections, may invade the orbit, erode the skull base and displace respectively the ocular bulb and the frontal lobe. The surgical treatment of this disease ranges from mini-invasive approaches, such as the transnasal endoscopic marsupialization, to a more aggressive surgery such as osteoplasty through coronal flap and frontal sinus exclusion by fat tissue.

METHODS

From 2005 to 2007, we treated with transnasal endoscopic surgery 10 patients, affected by frontal sinus mucopyoceles displacing both the ocular bulb and the frontal lobe.

RESULTS AND DISCUSSION

In the present study, we report the clinical and diagnostic features of this series, the treatment modalities and the achieved results and confirm the effectiveness of the mini-invasive transnasal endoscopic technique in the treatment of the frontal sinus mucopyocele.

Endovascular treatment of primitive persistent trigeminal artery aneurysm associated with middle cerebral artery aneurysm

We report the case of a primitive trigeminal artery aneurysm associated with an ipsilateral middle cerebral artery aneurysm. A 64-year-old Caucasian woman suffered from a severe acute headache. A head CT scan displayed subarachnoid hemorrhage and subsequent cerebral angiography showed right, wide-necked persistent trigeminal artery and ipsilateral middle cerebral artery aneurysms. The patient underwent embolization of both aneurysms with Guglielmi detachable coils. The association of a PPTA aneurysm and an ipsilateral MCA aneurysm has not been reported in the English literature.

Maldevelopmental pathology of the vertebral artery in infancy and childhood

The vertebral artery (VA), whose embryogenesis differs from that of any other vessel, is characterized by a great variety of malformations and anomalies. Some of the malformations are truly pathological (that is symptomatic); the anomalies are either found by chance postmorten or by angiography. All of these should be kept in mind by the surgeon approaching the deep cervical and craniospinal regions as well as by the interventional radiologist. In the context of a literature review we discuss the width and length anomalies of the VA, tortuosity and kinking, course anomalies, duplication and fenestration, persistence of primitive arteries, and anomalies of collateral branches. Other pathologies of the cervical VA associated exclusively with genetic diseases, such as spontaneous aneurysms and arteriovenous fistulae in neurofibromatosis type 1 are also considered.

Changes of cerebral energy metabolism and lipid peroxidation in rats leading to mitochondrial dysfunction after diffuse brain injury

The effect of mild closed head trauma, induced by the weight-drop method (450 g from a 1-m height), on lipid peroxidation and energy metabolism of brain tissue was determined at various times after cerebral injury in spontaneously breathing rats (1, 10, 30 minutes and 2, 6, 15, 24, 48, and 120 hours). Animals were continuously monitored for the evaluation of blood pressure, blood gases, heart rate, and intracranial pressure. Analysis of malondialdehyde (MDA) as an index of lipid peroxidation, ascorbic acid, high-energy phosphates, nicotinic coenzymes, oxypurines, and nucleosides was performed by high-performance liquid chromatography (HPLC) on neutralized perchloric acid extract of the whole brain. Data showed that MDA, undetectable in control, sham-operated rats, was already present within 1 minute of trauma (1.77 nmol/g wet weight; SD = 0.29) and reached maximal values by 2 hours (72.26 nmol/g w.w.; SD = 11.26), showing a progressive slow decrease thereafter. In contrast, ATP, GTP, and nicotinic coenzyme (NAD and NADP) concentrations showed significant reduction only by the second hour postinjury. Maximal decrease of the ATP and GTP concentrations were seen at 6 hours postinjury, whereas NAD and NADP concentrations showed maximum decline by 15 hours. Values recorded in mechanically ventilated rats did not differ significantly from those obtained in spontaneously breathing animals. These findings, supported by the absence of blood gas and blood pressure changes in the spontaneously breathing rats, strongly support the premise that biochemical changes (primarily lipid peroxidation) are not caused by secondary ischemic-hypoxic phenomena but rather are triggered by these forces acting on the brain at the time of impact. In addition, these results suggest that depression of energy metabolism might be caused by peroxidation of the mitochondrial membrane with a consequent alteration of the main mitochondrial function-that is, the energy supply.

The vertebral artery: developmental pathology

The vertebral artery (VA), whose embryogenesis is unique, different from that of any other vessel, is characterised by a great variety of malformations and anomalies. Some of the formers are truly pathological (that is symptomatic); the latter are just either anatomic or angiographic by chance findings. All of them should be kept in mind by the surgeon approaching the deep cervical and cranio-spinal regions, as well as by the interventional radiologist. Width and length anomalies of the VA, tortuosity and kinking, course anomalies, duplication and fenestration, persistence of primitive arteries, anomalies of collateral branches are discussed in the light of a literature review. Other pathologies of the cervical VA (spontaneous aneurysms and arteriovenous fistulae) associated exclusively with genetic diseases as neurofibromatosis type 1 (NF1) and fibro-muscular dysplasia (FMD) are also mentioned.

Paraganglioma of the cauda equina. Case report with 33-month recurrence free follow-up and review of the literature

Paraganglioma of the cauda equina is an unusual tumor and do not have the secretory properties of the same tumors arising outside the nervous system. In none of the few cases reported in literature a preoperative diagnosis was possible, and the surgical findings raised questions in the differential diagnosis with ependymomas. A rare case of paraganglioma of the cauda equina studied both pre- and postoperatively by MRI, and treated with subtotal excision combined with radiotherapy is described. Results and recurrence rates of the cases reported in literature are reviewed. Though MRI imaging has proven to be more sensitive than other radiological procedures, we stress the difficulties of preoperative diagnosis of paragangliomas in this site. The correct diagnosis of the paraganglioma of the cauda equina still relies on immunochemistry and electron microscopy. Total excision is often very difficult owing the tendency of these neoplasms to infiltrate cauda's roots. A 33-month recurrence free follow-up of our patient confirms that successful treatment is achieved by subtotal resection combined with radiotherapy.

Stereotactic-guided microsurgical removal of lesions without cortical appearance planned by three-dimensional CT reconstruction: limits and advantages of the frame-based technique

Intraoperative positioning still constitutes a basic problem in the microsurgical removal of intracerebral lesions, either deep-seated or without cortical appearance. We treated different types of lesions (cavernous angiomas, intraventricular tumors, gliomas, and metastases), by combining stereotactic targeting with the standard microsurgical technique. The dedicated software for the three-dimensional reconstruction of stereotactic CT images allowed us to determine the least traumatic surgical trajectory and the exact location of the lesion intraoperatively, with minimum manipulation of healthy cerebral tissue. We believe that the main indication for this technique is the removal of small, encapsulated or well-defined lesions without cortical appearance or in critical areas, while a direct inspection of the area is still essential in order to evaluate surgical removal in the case of infiltrating tumors.

Intracerebral Aspergillus abscess: case report and review of the literature

Intracranial aspergillosis is a rare pathologic condition, difficult to treat and often fatal, which generally affects immunodepressed patients. A case of brain abscess secondary to pulmonary localization in a patient with a non-Hodgkin lymphoma is described. The most significant clinico-pathological findings of intracranial aspergillosis are examined in the light of the relevant literature.

Treatment of the failed back surgery syndrome due to lumbo-sacral epidural fibrosis

The failed back surgery syndrome (FBSS) is a severe, long-lasting, disabling and relatively frequent (5-10%) complication of lumbosacral spine surgery. Wrong level of surgery, inadequate surgical techniques, vertebral instability, recurrent disc herniation, and lumbo-sacral fibrosis are the most frequent causes of FBSS. The results after repeated surgery on recurrent disc herniations are comparable to those after the first intervention, whereas repeated surgery for fibrosis gives only 30-35% success rate, and 15-20% of the patients report worsening of the symptoms. Computerized tomography (CT) with contrast medium and, in particular, Gd-DPTA enhanced MRI have recently allowed a differentiation between these two pathologies permitting us to adopt different therapies. In 1982-92 we applied spinal cord stimulation (SCS) as a first therapy of FBSS with proven lumbo-sacral fibrosis. Fifty-five patients underwent percutaneous trial SCS with a mono/multipolar electrode placed at the level of Th9-12. In the 36 patients who had a positive response to the trial stimulation, the electrode was connected to an implantable neurostimulator. On January '94 a third party, not involved in the treatment of the patients, controlled 34 of the 36 patients with a mean follow-up of 55 months. We classified the patients reporting at least 50% pain relief and satisfaction with result as successful, and 56% of the patients fell in that category. 10 out of 34 patients were able to resume their work. The success rate was significantly higher in females (73%) than in males, and in radicular rather than axial pain. Our data have led us to consider SCS as a first choice treatment in FBSS due to lumbo-sacral fibrosis.

Automated percutaneous discectomy in herniated lumbar discs treatment: experience after the first 200 cases

Two hundred patients presenting lumbo-sacral radicular pain were treated with automated percutaneous discectomy and were divided into two groups, on the ground of their symptomatology: group A included those patients that, otherwise, would undergo conservative therapy, because of their moderate pain; group B gathered patients whose severe pain needed undelayed surgery. The success rate that we reported in group A was 85%, while, in group B, it was 64%. Recurrences needing open surgery occurred in 15% of group B. Although characterized by delayed recovery, this technique seems to have good results even in so called surgical patients, in comparison with open surgery.