Wolfgang Deinsberger

Vertebral artery complications in anterior approaches to the cervical spine: report of two cases and review of literature.

BACKGROUND Cases of lesions to either the carotid artery or the vertebral artery in anterior approaches to the cervical spine are rarely found in medical literature. Two cases of vertebral artery injury in anterior approaches as well as a review of the pertinent literature are presented. In cases of arterial injury, appropriate management strategies are necessary to avoid or minimize harm to the patient. CASE REPORTS In the first case, the vertebral artery was injured during decompression of a cervical spinal stenosis while drilling the neuroforamen. Local compression provided sufficient control of hemorrhage. Nevertheless, rebleeding from a pseudoaneurysm occurred 2 days later. After removal of the hematoma, the pseudoaneurysm was treated successfully with coils by an endovascular approach. In the second case, misplacement of one screw in screw-fixation of a type II odontoid fracture caused a pseudoaneurysm of the vertebral artery. This led to a fatal subarachnoid hemorrhage 4 days later. CONCLUSIONS In ventral approaches to the cervical spine, precise preoperative planning and a detailed knowledge of the surgical anatomy are mandatory. In cases of injury to the vertebral arteries, direct surgical repair is most appropriate to prevent complications arising from fistulas, late-onset hemorrhages, pseudoaneurysms, thrombosis, and emboli. Alternatively, endovascular techniques or even clipping or ligation of the affected artery should be considered.

Experimental intracerebral hemorrhage: Description of a double injection model in rats

For experimental purposes, the most common technique of producing an intracerebral hematoma in rats is the injection of unclotted autologous blood. All modifications of this model share the problem that size and extension of the hematoma are not reproducible, because the injected blood either ruptures into the ventricular system or it extends to the subarachnoid or subdural space. Therefore a double injection model of experimental intracerebral hemorrhage in rats has been developed using 19 male Sprague-Dawley rats. After inducing anesthesia a cannula was stereotactically placed into the caudate nucleus and an intracerebral hematoma was produced with the double injection method in which first a small amount of fresh autologous blood is injected which is allowed to clot (preclotting) in order to block the way back along the needle track; the actual hematoma is produced in a second step of the injection. The clot volume was measured on stained serial sections. A total injection volume of 50 microliters of autologous blood produced intracerebral hematomas of 41.1 +/- 10.0 microliters and of similar shapes. The double injection method allows to generate reproducible hematomas in rats. This new model of intracerebral hemorrhage will allow further investigation of fibrinolytic and cytoprotective therapies.

Nitric oxide metabolites in cisternal CSF correlate with cerebral vasospasm in patients with a subarachnoid haemorrhage.

Summary. Background: The pathogenesis of cerebral vasospasm is likely to be multifactorial. Exposure of the adventitia of large cerebral arteries to blood breakdown products initiates a cascade of changes in both morphology and vasomotor regulation of the exposed vessels. The role of nitric oxide (NO) in development of cerebral vasospasm process is controversial. Basal cerebral vascular tone requires the continuous release of NO, nevertheless NO is involved in free radical mediated injury of endothelial cell membrane. Concentrations of nitrate/nitrite (stabile endproducts of NO metabolism) were studied in cisternal cerebrospinal fluid (cCSF) in patients suffering from aneurysmal subarachnoid haemorrhage (SAH). Method: 21 patients suffering from aneurysmal SAH were investigated. Treatment included aneurysm clipping, cisternal drainage of CSF and intravenous nimodipine in all patients as well as tripple H therapy when indicated. TCDS was performed on a daily basis. A mean flow velocity of more than 150 cm/sec and the development a delayed neurological deficit was defined as vasospasm. CSF samples were collected on the day of surgery and for the 7 days following. NO-M (nitrite and nitrate) were measured using a commercially available test kit. Findings: 5 of 21 patients developed clinically symptomatic vasospasm. There was a significant difference in NO levels between the groups. Patients with cerebral vasospasm showed significantly higher levels of NO-M in CSF than patients with a uncomplicated follow-up between day 2 and 8. Interpretation: Our preliminary results indicate that SAH leads to an increase in NO-M in CSF. This increase of NO-M significantly correlates with the flow velocities in TCDS measurement suggesting that NO plays an important role in the pathogenesis of cerebral vasospasm.

Increase of interleukin-6 plasma levels after elective craniotomy: Influence of interleukin-10 and catecholamines

SummaryAccidental and operative trauma are able to induce a systemic reaction of the organism characterized by fever, leukocytosis, catabolism, and an activation of the coagulation system. Interleukin-6 (IL-6) has been found to be an important mediator of this acute-phase response. In this study the influence of elective craniotomy on IL-6 plasma levels was evaluated. Blood samples were obtained from 20 patients undergoing elective craniotorny for vascular or tumorous diseases of the brain. IL-6 increased significantly (p < 0.05) from the pre-operative (0 (0–5.4) pg/ml) to the intraoperative (180 min after beginning of surgery) time-point (10.6 (0–18.5) pg/ml). The maximum was reached on the first postoperative morning (13.9 (4.3–45.0) pg/ml). Interleukin-10 (IL-10) is an anti-inflammatory cytokine which suppresses IL-6 synthesis in vitro in various cell lines. IL-10 plasma concentrations showed no alterations throughout the study period. Epinephrine plasma concentrations increased significantly from pre-operative values (15 (0–74) pg/ml) to the postoperative time-point (57 (9–459) pg/ml). A 4.5-fold increase (p < 0.05) of norepinephrine plasma concentrations was found when comparing the data obtained 60 min after beginning of surgery with the data of the first postoperative morning. In monocytes, which are a major source of plasma IL-6, an elevation of intracellular cAMP stimulates the IL-6 synthesis. The postoperative maximum of IL-6 in plasma could be due to a release of catecholamines. In conclusion this study demonstrated an elevation of IL-6 plasma concentrations during and after elective craniotomy. Increased plasma catecholamine concentrations as well as a damage in the blood-brain barrier due to the surgical trauma with a spill-over of IL-6 from brain tissue into plasma could have contributed to this result.

Transesophageal echocardiography as a guide for patient positioning before neurosurgical procedures in semi-sitting position.

With an incidence of a patent foramen ovale in nearly one fourth of the normal population, neurosurgical procedures in the semi-sitting position are associated with the risk of paradoxical air embolism. The present study was undertaken to evaluate an anesthetic concept to detect a patent foramen ovale with the help of transesophageal echocardiography in anesthetized patients before neurosurgical procedures in the semi-sitting position. Transesophageal echocardiography was performed after induction of anesthesia before surgery to avoid additional physical and psychologic stress for the patients. Thirty-five neurosurgical patients scheduled for elective surgery in the semi-sitting position were examined with help of contrast transesophageal echocardiography. The data of the examined patients were analyzed with respect to efficiency, logistic efforts, and adverse events. Contrast transesophageal echocardiography was combined with a ventilation maneuver to increase right atrial pressure. A patent foramen ovale was detected in 3 of 35 patients. These patients were operated on in a supine position. Oral insertion of the echoprobe was possible in all patients without difficulties. A short-lasting hypertension was observed in 5 patients despite adequate analgesia and sedation. The average time of examination was 25 minutes. None of the patients showed paradoxical air embolism as judged by postoperative neurologic assessment. Contrast transesophageal echocardiography combined with a ventilation maneuver is an effective method in detecting a patent foramen ovale. Moreover, transesophageal echocardiography is a clinical guide to patient positioning. The method of anesthetic management presented to examine anesthetized patients immediately before surgery means less physical and psychologic stress for the patients and causes approximately a 30-minute delay of surgery.

Somatosensory Evoked Potential Monitoring during Positioning of the Patient for Posterior Fossa Surgery in the Semisitting Position

OBJECTIVE Midcervical flexion myelopathy is a rare but well-known complication of posterior fossa surgery. To reduce the risk, we routinely used somatosensory evoked potential (SSEP) monitoring during positioning of the patient. METHODS Fifty-five consecutive patients were operated on for posterior fossa lesions in the semisitting position via a median (5 patients) or a lateral (50 patients) suboccipital approach. During positioning, monitoring of SSEPs by stimulation of the tibial nerve (T-SSEP) as well as by stimulation of the median nerve (M-SSEP) was established. In the case of pronounced SSEP changes, the head was repositioned. Surgery was started after SSEP recordings were unchanged as compared to the baseline investigation. RESULTS Effective monitoring was possible in all cases. Whereas M-SSEP recordings showed no changes while placing patients in the sitting position, T-SSEP recordings were altered in 14 cases (25%). In cases using the midline approach, SSEP changes were never so pronounced to require repositioning of the head. Head flexion and rotation resulted in significant changes of T-SSEP recordings in eight patients (14.5%), requiring repositioning. In two cases, an amplitude loss was noted. In only two of these eight patients were M-SSEP recordings markedly changed. SSEP recordings after repositioning disclosed recovery of spinal cord function. In no patient were clinical signs of myelopathy observed postoperatively. CONCLUSION We observed a high incidence of pronounced changes of T-SSEP recordings when the patients head was flexed and rotated for lateral suboccipital craniotomy in the semisitting position. Despite the low specificity monitoring of T-SSEPs during positioning of the patient for posterior fossa surgery, the semisitting position is strongly recommended.

Fibrinolysis and aspiration of experimental intracerebral hematoma reduces the volume of ischemic brain in rats.

The hypothesis was tested in rats that brain ischemia by an intracerebral hematoma can be ameliorated by fibrinolysis and aspiration of the hematoma. Intraparenchymal blood clots were generated by the injection of 50 microliters of autologous blood into the right caudate nucleus in two portions seven minutes apart. Thirty or 120 min later 12 microliters recombinant tissue plasminogen activator (rtPA) or 0.9% NaCl were injected and after 30 min the resolved hematoma was aspirated. Six hours later cerebral blood flow (CBF) was determined by 14C-iodoantipyrine autoradiography. Tissue volumes of CBF < 10 ml 100 g-1 min-1 and CBF < 30 ml g-1 min-1 were determined. Clot and lesion volume were quantified histologically from serial sections stained for succinate-dehydrogenase (SDH) activity. In rtPA-treated rats the major part of the hematoma could be evacuated 30 min as well as 120 min after production of the clot. The volume of ischemic brain (CBF < 10) was significantly reduced (p < 0.05) in the rtPA group compared to saline-treated and control groups irrespective of the time of treatment. In contrast, no difference was found between the control group and the experimental groups when the volumes of brain tissue surrounding the lesion were compared which had values of CBF < 30 ml 100 g-1 min-1. In a rat model of intracerebral hemorrhage, treatment by local fibrinolysis followed by aspiration of the hematoma is effective in reducing the volume of ischemic brain tissue and of the remaining clot volume.

Greater superficial petrosal nerve schwannoma

SummaryGreater superficial petrosal nerve (GSPN) schwannoma is a very rare type of facial nerve schwannoma. Including our case, only 6 schwannomas have been reported to originate from the GSPN. Clinical features, imaging, diagnosis, differential diagnosis and treatment are discussed reviewing other cases in the pertinent literature.

Cysteinyl-Leukotriene Levels in Intracerebral Hemorrhage:An Edema-Promoting Factor?

In 12 operatively (stereotactic aspiration and recombinant tissue-type plasminogen activator, rTPA) and 5 conservatively treated patients with spontaneous intracerebral hemorrhage the amounts of cysteinyl-leukotriene (cys-LT) released by blood-brain cell contact were measured by the urinary excretion of their metabolites during treatment. The mean cys-LT release before treatment was 14.51 ± 1.13 pg/mg creatinine/ml hematoma volume. The urinary cys-LT excretion at the end of the measurements was significantly lower in the operatively treated group than in the patients with conservative therapy (p < 0.05). We also found a significant correlation between the perifocal edema volume and the amount of cys-LT measured in patients’ urine (p < 0.01). In an additional animal experiment using dissociated rat brain cells plasmin was excluded as an activator for cerebral cys-LT formation, which emphasizes that rTPA did not influence cys-LT formation.

What the neurosurgeon needs to know about the coagulation system

Intracranial surgery is often complicated by thromboembolic events including the life-threatening pulmonary embolism. After head trauma and in patients with brain tumors disseminated intravascular coagulation (DIC) can occur, characterized by the triggering of the coagulation cascade and the depletion of coagulation factors which ultimately leads to bleeding. The identification of patients at high risk as well as the early diagnosis of hemostatic problems uses routine laboratory parameters such as partial thromboplastin time and prothrombin time reflecting the intrinsic and the extrinsic pathway of the coagulation respectively. Thrombin antithrombin III complexes (TAT) and prothrombin fragment 1 + 2 (F1 + 2) are further indicators of an activation of the coagulation whereas fibrinogen degradation products (FDP) refer to the fibrinolytic system. The basic principles of coagulation and fibrinolysis are summarized as well as the changes of laboratory parameters accompanying DIC, hypercoagulability and hyperfibrinolysis.