Continuous-wave near-infrared spectroscopy is not related to brain tissue oxygen tension.

Near-infrared spectroscopy (NIRS) has gained acceptance for cerebral monitoring, especially during cardiac surgery, though there are few data showing its validity. We therefore aimed to correlate invasive brain tissue oxygen measurements (PtiO2) with the corresponding NIRS-values (regional oxygen saturation, rSO2). We also studied whether NIRS was able to detect ischemic events, defined as a PtiO2-value of <15 mmHg. Eleven patients were studied with invasive brain tissue oxygen monitoring and continuous-wave NIRS. PtiO2-correlation with corresponding NIRS-values was calculated. We found no correlation between PtiO2- and NIRS-readings. Measurement of rSO2 was no better than flipping a coin in the detection of cerebral ischemia when a commonly agreed ischemic PtiO2 cut-off value of <15 mmHg was chosen. Continuous-wave-NIRS was unable to reliably detect ischemic cerebral episodes, defined as a PtiO2 value <15 mmHg. Displayed NIRS-values did not correlate with invasively measured PtiO2-values. CW-NIRS should not be used for the detection of cerebral ischemia.

CT angiography as a confirmatory test in brain death.

OBJECTIVE: From recent studies, it remains unclear whether CT angiography could be an alternative to other established ancillary tests for the diagnosis of brain death. We examined intracranial contrast enhancement in CT angiography after clinically established brain death and compared the results with EEG and TCD findings. MATERIALS AND METHODS: Prospective study between April 2008 and January 2010. EEG, TCD and CT angiography were performed in 40 patients aged between 18 and 88 years (mean 56 years) who fulfilled the clinical criteria of brain death. RESULTS: In all cases, the common carotid artery, cervical internal carotid artery, cervical vertebral artery and superficial temporal artery opacified in an arterial CT angiography series. 37 out of 40 cases demonstrated no opacification of both MCA-M4, ACA-A3, PCA-P2 segments, and BA. CONCLUSION: CT angiography is a promising method of evaluating intracranial circulatory arrest in brain death with a high spatial and temporal resolution, superior to all other established technical procedures. The examination is easily accessible in most hospitals, operator independent, minimally invasive and inexpensive. Therefore, CT angiography has the potential to enlarge the existing armamentarium of confirmatory brain death tests.

Effect of intraarterial papaverine or nimodipine on vessel diameter in patients with cerebral vasospasm after subarachnoid hemorrhage.

INTRODUCTION: Papaverine (P) and nimodipine (N) are the most widely used vasodilators when angiographic and symptomatic vasospasm is present after subarachnoid aneurysmatic hemorrhage (SAH). Their effect is only short-lived and no direct comparisons have been undertaken to evaluate the action of both substances directly. We retrospectively assessed the effect of either P or N on angiographic diameter reduction and capillary blood flow. METHODS: Fifteen SAH patients with secured aneurysms and cerebral vasospasm received intraarterial P, fifteen similar patients received N. As the primary endpoint, pre- and post-infusion arterial diameters and capillary blood flow were rated retrospectively on angiographies and compared by RM-ANOVA. Secondary endpoints were the difference in the modified Rankin Scale between the two groups on admission and at discharge, the occurrence of delayed cerebral ischemia, the separate effects on angiographic diameter and capillary blood flow and the overall response rate to the vasodilator infusion. RESULTS: Angiographic resolution of diameter reduction and angiographically assessed capillary blood flow together differed not significantly between both groups. P infusion dilated all angiographic demonstrable vessels while N infusion was ineffective in 16% of the patients. Capillary flow on pre- and post-infusion angiographies was not different between the two groups. CONCLUSION: P and N seem to differ in the effect on cerebral diameter reduction in patients with vasospasm after SAH. The clinical implications remain to be established. A multimodal approach, perhaps combining different agents for intraarterial infusion in such patients, needs to be evaluated.

Anterior interosseous nerve compression syndrome: is there a role for endoscopy?

BACKGROUND: Anterior interosseous nerve syndrome is characterized by paralysis of the flexor digitorum profundus, the flexor pollicis longus and the pronator quadratus muscles without sensory loss. Extended exploration of the anterior interosseous nerve is the surgical treatment of choice. The present study evaluates the feasibility of an endoscopic approach for nerve decompression. METHODS: Preparation of the anterior interosseous nerve was performed in ten human cadaver arms. Subsequently, one female patient suffering from anterior interosseous nerve syndrome was endoscopically operated on. FINDINGS: A skin incision of 3-4 cm in the proximal direction was made at the forearm, and the median nerve was visualized between the pronator teres muscle and the flexor digitorum superficialis. Subsequently, the anterior interosseus nerve branch was identified, followed distally and decompressed under endoscopic view. The procedure could be accomplished in all cases under endoscopic view. Due to the very steep surgical angle, a branch of the anterior interosseus nerve was injured in one cadaver case. In all other cases, no adverse effects were observed. In the clinical case, the anterior interosseus nerve was endoscopically identified and decompressed, but a skin incision of 5 cm was required. CONCLUSIONS: The results demonstrate that an endoscopic decompression of the anterior interosseus nerve is possible. Several difficulties occurred: Due to the depth of the surgical approach, especially in case of bulky muscles and very small skin incisions, the view is limited, harboring a higher risk of nerve injury. With more experience and specially designed endoscopes, application of this technique in anterior interosseus nerve compression syndrome might become more feasible.

Mesencephalic ependymal cysts: treatment under pure endoscopic or endoscope-assisted keyhole conditions.

OBJECT: Primary intracranial ependymal cysts are extremely rare. Similar to congenital intraparenchymal cysts in the mesencephalon they usually occur with symptoms of an occlusive hydrocephalus or symptoms like Parinaud syndrome, dizziness, or gait disturbance. The objective of this study was to evaluate the surgical methods for the treatment of these cysts and the clinical outcome of the patients. METHODS: The authors present the clinical records of 8 patients who were treated in their department for symptomatic mesencephalic ependymal cysts in the past 10 years. The patient age ranged from 22 to 60 years with a mean age of 44 years. In 4 cases the authors performed a suboccipital infratentorial supracerebellar approach by using endoscope-assisted microsurgery. The other 4 patients underwent a pure endoscopic procedure over a frontal bur hole trepanation. RESULTS: Four patients became symptom free, and the remaining 4 improved significantly after a mean follow-up duration of 38.5 months (range 5-119 months). One patient underwent 2 operations: first a ventriculocystostomy and 4 months later endoscopic third ventriculostomy because of recurrent hydrocephalus. In 1 case a second surgery was necessary because of a wound infection. In all of the patients an adequate fenestration of the cyst was achieved. CONCLUSIONS: A symptomatic mesencephalic ependymal cyst is an indication for neurosurgical intervention. These cysts can be treated successfully and most likely definitively by a pure endoscopic or endoscope-assisted keyhole neurosurgical technique. There were no morbid conditions or death due to the procedures in this group of 8 patients. Therefore, the authors regard these surgical procedures to be good alternatives to treatments such as shunt placement or stereotactic aspiration of the cysts.

Endoscopic endonasal pituitary surgery: surgical and outcome analysis of 50 cases.

OBJECTIVE: Microsurgical transsphenoidal surgery for pituitary tumors has been standard therapy for decades and was established by Harvey Cushing in the early twentieth century. Today, endoscopy is increasingly accepted in the therapy of pituitary lesions. In this retrospective study, we analysed the surgical technique and outcome of 50 patients with pituitary lesions treated with an endoscopic endonasal trans-sphenoidal approach. METHODS: Between January 2004 and July 2005, 50 patients (30 female and 20 male) with pituitary tumors were operated upon using an endoscopic endonasal trans-sphenoidal procedure without nasal speculum or postoperative nasal packing. The follow-up period ranged from 3 to 18 months. RESULTS: All patients had normal airways through both nostrils immediately after extubation. Postoperative discomfort was minimal and hospitalization was 4-5 days. Three patients developed postoperative transient diabetes insipidus, persisting in one for a further 2 months. Among the 50 patients, total tumor removal was achieved in 47 patients (94%), subtotal in two patients (4%). One patient died intraoperatively due to subarachnoid haemorrhage. CONCLUSION: The endoscopic endonasal transsphenoidal approach for removing pituitary lesions is a form of minimally invasive surgery offering excellent postoperative results.

Computed tomographic angiography as a useful adjunct in the diagnosis of brain death.

BACKGROUND: Because of its widespread accessibly, computed tomographic angiography (CT-A) is a promising technique in the detection of intracranial circulatory arrest in brain death (BD). Several studies assessed this tool, but neither have standardized evaluation parameters been developed nor has information about specificity become available. METHODS: We conducted a prospective study between January 2008 and April 2012. Thirty patients were admitted to our University Hospital (16 men and 14 women; age, 18-88 years) and underwent CT-A scanning at two occasions: immediately after the first signs of loss of brain stem reflexes and after definitive determination of brain. The results of CT-A were compared with transcranial Doppler ultrasonography and electroencephalogram. RESULTS: In 3 of 30 patients, we observed a termination of contrast flow at the level of the skull base and foramen magnum in arterial scanning series before the clinical determination of BD. After the clinical determination of BD, the opacification of all vascular territories in arterial phase scanning was found in one case, but venous phase scanning revealed no blood return in internal cerebral veins. In all other cases, contrast filling ceased at level of skull base or below. The specificity of CT-A in the detection of intracranial circulatory arrest was 90%, and sensitivity was 97%. CONCLUSION: CT-A is reliable and appropriate technical investigation to detect intracranial circulatory arrest in BD. The evaluation of contrast enhancement in arterial phase scanning seems to be more reliable than that in venous phase. An international consensus about a uniformly applied CT-A protocol for the evaluation of BD should be established.

First clinical results with a new telemetric intracranial pressure-monitoring system.

BACKGROUND: The knowledge of intracranial pressure (ICP) is the basis of an appropriate neurosurgical treatment. Because clinical, fundoscopic, or radiological data alone are often elusive, a pre- or postoperative long-term monitoring of the ICP itself is desirable. OBJECTIVE: We describe the first clinical experiences with a new telemetric ICP-monitoring device. METHODS: The transducer of this telemetric intraparenchymal pressure probe is placed under the galea over the calvaria. ICP can be monitored via a special telemetric reader, placed over the intact skin, and the ICP values are stored in a small portable computer. The system does not require an intensive care environment and can be used in any ward or even at home. The system was successfully applied in 10 patients (age, 3-56 years) in whom raised ICP due to hydrocephalus, shunt dysfunction, endoscopic third ventriculostomy failure, craniostenosis, or pseudotumor cerebri was suspected. RESULTS: Continuous telemetric monitoring of ICP was performed for 2 to 24 weeks. In 7 patients, increased ICP values could be excluded, and further surgical maneuvers were avoided. In 3 patients, repeated plateaus or continuously raised ICP indicated surgery resulting in a normalization of ICP. CONCLUSION: This new telemetric system was safe and effective for ICP measurement over a long period, including home monitoring. For the patients, it was easy to handle, and reliable data could be recorded over many weeks. Based on this preliminary experience, the authors consider the new system extremely advantageous in surgical decision making in particularly difficult cases of suspected abnormalities of ICP.

Technical aids in the diagnosis of brain death: a comparison of SEP, AEP, EEG, TCD and CT angiography.

BACKGROUND: The use of technical aids to confirm brain death is a controversial matter. Angiography with the intra-arterial administration of contrast medium is the international gold standard, but it is not allowed in Germany except in cases where it provides a potential mode of treatment. The currently approved tests in Germany are recordings of somatosensory evoked potentials (SSEP), brain perfusion scintigraphy, transcranial Doppler ultrasonography (TCD), and electroencephalography (EEG). CT angiography (CTA), a promising new alternative, is being increasingly used as well. METHODS: In a prospective, single-center study that was carried out from 2008 to 2011, 71 consecutive patients in whom brain death was diagnosed on clinical grounds underwent recording of auditory evoked potentials (AEP) and SSEP as well as EEG, TCD and CTA. RESULTS: The validity of CTA for the confirmation of brain death was 94%; the validity of the other tests was: 94% for EEG, 92% for TCD, 82% for SSEP, and 2% for AEP. In 61 of the 71 patients (86%), the EEG, TCD and CTA findings all accorded with the clinical diagnosis. The diagnosis of brain death was established beyond doubt in all patients. CONCLUSION: In this study, the technical aids yielded discordant results in 14% of cases, necessitating interpretation by an expert examiner. The perfusion tests, in particular, can give false-positive results in patients with large cranial defects, skull fractures, or cerebrospinal fluid drainage. In such cases, electrophysiologic tests or a repeated clinical examination should be performed instead. CTA is a promising, highly reliable new method for demonstrating absent intracranial blood flow. In our view, it should be incorporated into the German guidelines for the diagnosis of brain death.

Simple endoscopic decompression of cubital tunnel syndrome with the Agee system: anatomic study and first clinical results.

BACKGROUND: Simple decompression in ulnar nerve compression syndromes offers options for endoscopic applications. OBJECTIVE: The authors present their initial experience with the Agee device. PATIENTS AND METHODS: The monoportal endoscopic technique (Agee system) was evaluated on 10 cadaveric arms. Subsequently, 32 arms of 29 patients were operated on between January 2006 and March 2009. All patients presented with typical clinical signs and neurophysiologic studies. Long-term follow-up examinations were obtained in 27 of 32 arms. RESULTS: In the cadaver study, the ulnar nerve was always correctly identified. No nerve damage occurred, and sufficient decompression of the ulnar nerve was always achieved. In the clinical series, no intraoperative complications were observed. A change to open technique was not required, and no worsening of the cubital tunnel syndrome occurred. Two wound infections required surgical wound cleaning. Wound hematomas treated conservatively were found in 5 cases. On long-term follow-up, an improvement in the McGowan- Classification was achieved in 22 of 27 cases. One patient was operated on by open surgery after endoscopic surgery. CONCLUSION: The endoscopic technique for ulnar nerve entrapment syndrome using an Agee device appears to be safe and efficient. The results are comparable to those achieved with simple open decompression. A randomized prospective study should be performed to further evaluate the value of new technique in ulnar nerve entrapment syndrome.

Tumors of the lateral and third ventricle: removal under endoscope-assisted keyhole conditions.

OBJECTIVE: Intraventricular tumors usually are managed by approaches and microsurgical techniques that need retraction and dissection of important brain structures. Minimally invasive endoscopic procedures achieve a remarkable alternative to conventional microneurosurgical techniques. Endoscope-assisted microneurosurgery may be a minimally invasive technique with maximally effective treatment. Using the keyhole concept for planning the surgical strategy, the reduction of the brain retraction is achieved, which is one of the main benefits of this technique. METHODS: We treated 35 patients (16 female patients and 19 male patients) with tumors in the lateral (n = 8) and the third (n = 27) ventricle. Patient age at the date of surgery ranged from 5 to 73 years. The follow-up period ranged from 6 to 83 months. The tumors were operated on using transcortical, transcallosal, or suboccipital transtentorial or infratentorial supracerebellar approaches after precise planning of the skin incision, the trephination, and the trajectory to the center of the tumor, performed earlier with a magnetic resonance imaging scan. RESULTS: Total removal of the tumor was achieved in 28 patients (78.5%). In 2 patients (6.5%), recurrent tumor occurred. In 5 patients (15%), parts of the tumors remained because of infiltration of eloquent areas. Overall clinical improvement was achieved in 31 patients (87%). Three patients (10%) were unchanged and 1 patient (3%) deteriorated. CONCLUSION: Endoscope-assisted keyhole neurosurgery seems to be a safe method of removing tumors in all regions inside the ventricular system with a low risk of permanent neurological deficits. The exact surgical corridor planning on the basis of the keyhole strategy offers less traumatic exposure of even deep-seated endoventricular tumors.

Tumors of the lateral and third ventricle: removal under endoscope-assisted keyhole conditions.

OBJECTIVE: Intraventricular tumors usually are managed by approaches and microsurgical techniques that need retraction and dissection of important brain structures. Minimally invasive endoscopic procedures achieve a remarkable alternative to conventional microneurosurgical techniques. Endoscope-assisted microneurosurgery may be a minimally invasive technique with maximally effective treatment. Using the keyhole concept for planning the surgical strategy, the reduction of the brain retraction is achieved, which is one of the main benefits of this technique. METHODS: We treated 35 patients (16 female patients and 19 male patients) with tumors in the lateral (n = 8) and the third (n = 27) ventricle. Patient age at the date of surgery ranged from 5 to 73 years. The follow-up period ranged from 6 to 83 months. The tumors were operated on using transcortical, transcallosal, or suboccipital transtentorial or infratentorial supracerebellar approaches after precise planning of the skin incision, the trephination, and the trajectory to the center of the tumor, performed earlier with a magnetic resonance imaging scan. RESULTS: Total removal of the tumor was achieved in 28 patients (78.5%). In 2 patients (6.5%), recurrent tumor occurred. In 5 patients (15%), parts of the tumors remained because of infiltration of eloquent areas. Overall clinical improvement was achieved in 31 patients (87%). Three patients (10%) were unchanged and 1 patient (3%) deteriorated. CONCLUSION: Endoscope-assisted keyhole neurosurgery seems to be a safe method of removing tumors in all regions inside the ventricular system with a low risk of permanent neurological deficits. The exact surgical corridor planning on the basis of the keyhole strategy offers less traumatic exposure of even deep-seated endoventricular tumors.