Large interarcuate spaces in the cervical vertebral column of the tyrolean mountain sheep.

Large interarcual spaces have been described between the arcus vertebrae C5/C6 and C6/C7 in the cervical vertebral column of Nubian goats. This aperture enables direct access to spinal cord and rootlets without the need to perform a hemilaminectomy. The present study was performed in order to determine whether these large interarcual spaces can also be found in the vertebral column of the Tyrolean mountain sheep, as this small ruminant, which is anatomically very similar to the Nubian goat, is frequently used for experimental purposes at the Surgical University Clinic in Austria. The carcasses of 10 sheep (six females, four males; range of age: 2.5-6 years, range of weight: 52-89 kg) were dissected and the vertebral column was exposed. All 10 sheep showed elliptic openings between the fourth cervical and the first thoracal vertebrae. Three sheep had additional openings between the first and the second thoracal vertebrae. All openings were covered solitarily by the ligamentum flavum and under this ligamentum lay the spinal cord without any further osseous or ligamentous protection. These findings are not mentioned in the common textbooks of veterinary anatomy and deserve attention, as they can be a step forward towards non-traumatic experimental surgery on the spinal cord.

Short segment stimulation of the anterior transposed ulnar nerve at the elbow.

OBJECTIVE: To determine whether short segment stimulation after anterior subcutaneous transposition of the ulnar nerve reaches normal values and correlates with postoperative clinical findings. DESIGN: Comparative cross-sectional study. SETTING: Outpatient clinic of a university department of physical medicine and rehabilitation. PATIENTS: Nineteen patients (15 men, 4 women) with 21 surgically treated ulnar neuropathies at the elbow; and 19 healthy controls (11 men, 8 women) with 24 measured nerves. INTERVENTIONS: Assessed motor function of ulnar innervated muscles and staged into 4 categories; used questionnaire to assess clinical course of the nerve lesion and graded into 5 categories; took electrophysiologic recordings to measure motor conduction velocity and compound muscle action potentials; and studied short segment stimulation across elbow and lower arm. MAIN OUTCOME MEASURES: Mean +/- standard deviation of ulnar short segment conduction time across the elbow, amplitude and motor conduction velocity; grading of ulnar nerve lesions; grading of the course of disease after surgery; and logistic regression and correlation (Spearman's correlation coefficient) for electrophysiologic and clinical parameters. RESULTS: Sixteen nerves showed focal conduction slowing in patients. No significant correlation between the course of disease and electrophysiologic parameters was seen. For stepwise logistic regression, there was a significant effect between grade of nerve lesion and amplitude, but no significant effect between the course of disease and electrophysiologic parameters. CONCLUSION: A focal conduction slowing across the elbow after anterior subcutaneous transposition does not correlate with postoperative clinical findings.

Neuroblastoma cells provoke Schwann cell proliferation in vitro.

BACKGROUND: A subset of human neuroblastomas (NBs) has the capacity to mature completely, imitating sympathetic ganglia. Previously, we showed that the neuronal population in spontaneously maturing NBs usually has a near-triploid DNA content without 1p deletions, and we concluded that the constantly diploid Schwann cells (SCs) do not belong to the neoplastic component of these tumours. We therefore hypothesised that NB cells are able to stimulate SC proliferation, and that SCs trigger NB differentiation. PROCEDURE: We performed in vitro experiments to test this model and to test whether SCs can also influence the growth of aggressive NBs. Human SCs were co-cultivated with NB tumours and cell lines, and were harvested after defined time intervals. Proliferative activity of the SCs and the NB cells was determined by visualisation of 5-bromo-2'-deoxyuridine (BrdU) incorporation or Ki-67 staining. Neurite outgrowth and neurofilament (NF) expression were analysed immunocytochemically and apoptotic rate was determined by a terminal deoxynucleotidyl transferase-mediated dUTP-X fluorescein nick end labelling (TUNEL) assay. RESULTS: Human NB tumours or cell lines unequivocally increased the proliferation of SCs in vitro. In cocultivated NB cells, the proliferative activity was not altered in the first days of cocultivation, although neurite outgrowth and NF expression were enhanced. However, after 10 days, the mitotic rate of neuroblastic cells decreased and the apoptotic rate showed a marked increase. CONCLUSIONS: The results of the cocultivation experiments provide an experimental hint that the in vivo growth of SCs in NBs is caused by the neoplastic neuroblasts, and they also indicate that cells from peripheral nerves can influence the growth of aggressive NB cells if cocultivated.

Leprosy affects the tibial nerves diffusely from the middle of the thigh to the sole of the foot, including skip lesions.

This study investigated where leprosy affects the posterior tibial nerve and whether neurolysis is beneficial. Nine patients with bilateral posterior tibial leprous neuropathy with no sensorimotor recovery were studied. Preoperative sensory-muscle and nerve conduction velocity testing revealed the tarsal tunnel to be the site of a severe lesion in all cases. During surgery, the most proximal site of the nerve lesion was detected by electrically stimulating the spinal roots from the second lumbar nerve to the fourth sacral nerve, evoking efferent mixed nerve compound action potentials that were recorded from the exposed tibial nerve. In all patients, the nerve compound action potentials became normal only proximal to the sciatic nerve bifurcation. Epineuriotomy within these seemingly unaffected segments revealed fibrosis of the interfascicular epineurium. Interfascicular neurolysis was performed on all affected segments. A 2-year follow-up showed an increase in girth of the proximal calf musculature in six of eight patients (the ninth patient had no recordable nerve conduction velocity). It was concluded that (1) leprosy affects the tibial nerves in a scattered way from the sciatic nerve main trunk distally to the exit of the tarsal tunnel; and (2) interfascicular, microsurgical neurolysis is beneficial provided that it is performed on all affected nerve segments.

Depressive effect of isoflurane on motor evoked potentials in the Nubian goat.

PURPOSE: To determine the effect of isoflurane on motor evoked potentials (MEP) in a new animal model designed to verify the applicability of MEPs in brachial plexus surgery, and to compare the results with previous reports in other animals. METHODS: In seven goats, anesthesia was induced with 3 mg x kg(-1) ketamine i.v. and maintained with nitrous oxide 40% in oxygen and 2 microg x kg(-1) x hr(-1) fentanyl i.v.. The MEP were performed with two subcutaneous needle electrodes placed over the occiput (cathode) and the nasion (anode), with their plugs connected to the power output of a Digitimer D 180 electrical stimulator, connected to the trigger input of an electromyograph (model 8400, Cadwell Laboratories, Inc., Kennwick, Washington). Activation of the Digitimer caused central stimulation of the motor cortex, evoking baseline compound muscle action potentials (CMAPs) which were recorded from the left triceps muscle. Subsequently, isoflurane 2% was administered together with repeated central stimulation at 30 sec intervals. RESULTS: Onset of I- (indirect) waves increased from median 15,8 msec to median 26,8 msec P = 0,018 (latency increase ranged from: 9 to 11.5 msec), while peak-to-peak amplitudes decreased and subsequently disappeared. D- (direct) waves showed no latency increase, and finally disappeared as well. After disappearance of CMAPs, isoflurane administration was stopped and MEP repeated. The CMAPs reappeared (range: 210-360 sec) and regained initial peak-to-peak amplitudes and latencies. CONCLUSION: These animal studies suggest that isoflurane should not be used during the recording of MEPs.

Controlled partial skin thickness burns: an animal model for studies of burnwound progression.

A practicable, reliable and reproducible model for infliction of partial skin thickness burn lesions in rabbits is presented. The model is dedicated to experimental studies investigating the influence of drugs on burn wounds. A round aluminium stamp with a contact area of 4 cm2, weight 85 g, was heated up to 80 degrees C and applied for 14 s without additional pressure on the depilated dorsal skin of rabbits. This procedure produced the desired partial skin thickness burn injury. The depth of the burn lesions was investigated by HE-stained paraffin sections. The border of the necrotic zone was found in the central third of the dermis in 80% of cases, and in the central two quarters in 100%. These results are achieved when the rabbit's hair at the site of infliction is in the anagen phase of the hair growth cycle. For obtaining reproducible results we recommend using rabbits of the same strain and weight, anagen hair growth phase, the described procedure of infliction, an identical stamp and the specified temperature and infliction time.

Memantine for prevention of spinal cord injury in a rabbit model.

BACKGROUND: This study was conducted to investigate the effect of memantine, a noncompetitive N-methyl-d-aspartate receptor antagonist, on the neurologic outcome of spinal cord ischemia after aortic occlusion. MATERIALS AND METHODS: New Zealand White rabbits were anesthetized and spinal cord ischemia was induced for 40 minutes by infrarenal aortic occlusion. Animals were randomly allocated to 3 groups. Group 1 (n = 8, control) received no pharmacologic intervention, group 2 (n = 8) received intra-aortic memantine infusion (20 mg/kg) after aortic crossclamping, and group 3 (n = 8) was treated with systemic memantine infusion (20 mg/kg) 45 minutes before aortic occlusion. Neurologic status was scored by the Tarlov system (in which 4 is normal and 0 is paraplegia) at 12, 24, 36, and 48 hours after the operation. Lumbar spinal root stimulation potentials and motor evoked potentials from lower limb muscles were monitored before, during, and after the operation. After the animals were killed, the spinal cords were studied histopathologically. RESULTS: All potentials disappeared shortly after aortic crossclamping. They returned earlier in both memantine-treated groups than in the placebo group. Histologic examination of spinal cords revealed a few abnormal motor neurons in memantine-treated rabbits but found extensive injury in the control group. At 12 hours the median Tarlov scores were 0 in the control group (group 1), 2 in the intra-aortic memantine group (group 2, P =.001 versus control), and 3 in the systemic group (group 3, P =.0002 versus control). At 24 hours median Tarlov scores were 0, 2.5 (P =.0002), and 4 (P =. 0002), respectively. Finally, at both 36 and 48 hours median Tarlov scores were 0, 3 (P =.0006), and 4 (P =.0002), respectively. CONCLUSION: Memantine significantly reduced neurologic injury related to spinal cord ischemia and reperfusion after aortic occlusion.

Leprosy affects facial nerves at the main trunk: neurolysis can possibly avoid transfer procedures.

The predilective sites of lesions in leprous peripheral nerves are well established, and their surgical decompression is common practice when sensorimotor disorders persist after medication. By contrast, the precise localization of leprous facial neuropathy still remains unclear, and musculofascial transfers have been the only type of surgical treatment. The goal of this study was to clarify where leprosy affects facial nerves and to determine whether neurolysis might suffice to restore facial function. In five Indian and two Egyptian patients suffering from leprous facial neuritis, the nerves were stimulated transcranially at the brainstem to evoke efferent motor nerve action potentials, which were recorded from the exposed nerves. Lesions were detected at the main trunk proximally from the first bifurcation in all cases. Epineuriotomy revealed fibrosis of the interfascicular epineurium in all instances, as an indication for interfascicular neurolysis. One patient was able to close his eye and showed a better smile soon after surgery. After 16 and 21 months, respectively, one patient had improved distinctly, two patients slightly, two patients showing no progress, and two patients were lost to follow-up. It is concluded that (1) leprous facial neuropathy is located at the main trunk close to the first bifurcation and not exclusively at the peripheral zygomatic branches, (2) microsurgical neurolysis can be considered in leprous facial neuropathy before transfer procedures as long as voluntary or spontaneous activity is present in the affected muscles, and (3) intraoperative transcranial electrical stimulation is an effective means of localizing the site and proximal extent of leprous facial neuropathy.

[Prevalence of abdominal aortic aneurysms: a sonographic screening study]. / Prävalenz des abdominellen Aortenaneurysmas: Eine sonographische Screeningstudie.

PURPOSE: To determine the prevalence of abdominal aortic aneurysms (AAA) in males above 60 years of age. METHODS: 1043 males of 60 years of age or older underwent sonographic examinations of the abdominal aorta. All of the candidates had volunteered for the examination, and special care was taken to avoid preselection of the candidates. Wherever possible, information was obtained on the following risk factors: cholesterol level, nicotine, diabetes, insulin and other medication, hypertonia and cardiac risk. RESULTS: An AAA was diagnosed in 2.59% of the cases, while ectasia of the abdominal aorta was detected in 11.89%. The mean diameter of the aneurysms was 39.1 mm. Significant correlations between the various risk factors and abnormalities of the abdominal aorta could be established in patients suffering from angina pectoris (p = 0.004) and from congestive heart failure (p = 0.014). CONCLUSIONS: AAA in males above 60 occurs in 2,590 out of 100,000 cases. The most noteworthy risk factors in the development of AAA are cardiovascular disorders.

Intraoperative electroneurodiagnostics (transcranial electrical motor evoked potentials) to evaluate the functional status of anterior spinal roots and spinal nerves during brachial plexus surgery.

Intradural spinal root lesions cannot be recognized by dissecting the brachial plexus and lead to ineffective surgery if they remain undetected. Therefore, patients need to undergo a diagnostic procedure to assess the intradural status of the spinal roots. Although motor recovery is the main goal of brachial plexus surgery, the techniques currently applied do not permit adequate evaluation of the anterior root. In search of an alternative, we performed intraoperative motor evoked potentials. Ninety spinal nerves in 19 patients suffering from brachial plexus lesions were dissected. Twenty-seven spinal nerves were avulsed; 8 nerves were disrupted and 17 were completely scarred, resulting in 25 stumps. Thirty-eight nerves appeared to be undamaged. On central stimulation, nerve compound action potentials were recorded from the exposed spinal nerves. Nerve compound action potentials could only be recorded from 21 stumps and from 32 apparently undamaged nerves. No recordings were obtained from 4 stumps and 7 spinal nerves in continuity. According to these findings, it is highly probable that surgery would have been insufficient in 10 spinal nerves if intraoperative motor evoked potentials had not been performed. We conclude that (1) intraoperative motor evoked potentials are an effective means for investigating the functional status of anterior motor roots and motor fibers in exposed spinal nerves, and (2) the use of motor evoked potentials should be considered during brachial plexus surgery to improve interventions.

Motor evoked potential as a reliable method to verify the conductivity of anterior spinal roots in brachial plexus surgery: an experimental study on goats.

The goal of this experimental study was to confirm the reliability of motor evoked potential (MEP) in testing the function of anterior motor roots in brachial plexus surgery. On central stimulation, nerve compound action potentials (NCAPs) are registered from the exposed spinal nerves. If NCAPs can be recorded, the anterior root is considered to be intact. Two factors might cause positive recordings even in the presence of an avulsed anterior motor root: volume conduction, and impulse transmission through an intact posterior root. In five Nubian goats, spinal nerves C6, C7, and their corresponding spinal roots were dissected. On central stimulation, NCAPs were repeatedly recorded from the surface of all ten spinal nerves. Then, the anterior motor roots were transsected and central stimulation repeated. NCAPs disappeared irreversibly in all ten tested spinal nerves. The experiment showed that, on central stimulation, NCAPs cannot be recorded from spinal nerves unless the anterior root is intact.

Intraoperative electroneurodiagnostics to detect a second granuloma in the cubital area of median nerves affected by leprosy: a new approach to prevent incomplete surgery.

A recent work reports on the necessity to localize the most proximal site of leprous ulnar neuritis with intraoperative electroneurodiagnostics. In the present study we wanted to verify the applicability of this method on leprous median nerves. In six patients, seven median nerves were exposed at the wrist, all showing a typical leprous granuloma there. Spinal roots C5 to Th1 were then stimulated intraoperatively, evoking efferent mixed nerve compound action potentials (NCAPs) which were registered from the nerve's surface. No recordings could be obtained on the granuloma in all patients, neither distally nor shortly proximal from it, nor even further central at the forearm's proximal third where the median nerve exits the cubital area. Prior to dissecting the nerves in this precarious region, they were exposed at the arm's distal third, looking inconspicuous in all cases. Recordings could finally be obtained there, and subsequent exposure further proximal showed no increase in amplitude of the NCAPs, but there was a sharp decrease distally. In all cases, subsequent dissection of the cubital area revealed a second leprous granuloma extending variably from the distal third of the arm to the two heads of the pronator teres muscle, requiring microsurgical release. Intraoperative spinal root stimulation is an effective method to detect a second leprous granuloma and to avoid incomplete surgery in median nerves affected by leprosy.

The radial sensory nerve entrapped between the two slips of a split brachioradialis tendon: a rare aspect of Wartenberg's syndrome.

A retrospective study was designed to verify how often an anatomic variation caused the radial sensory nerve entrapment at the forearm (Wartenberg's syndrome). This variation, in which the superficial branch of the radial nerve emerges from under the fascia between two slips of a split brachioradialis tendon, was mentioned once in a clinical textbook as a basis for nerve entrapment but was found to occur in 5 of 150 dissected arms in 4 of 75 cadavers (3.3% of the investigated arms) in a recent anatomic study. To evaluate the incidence of this variation, 143 operative reports from patients who had Wartenberg's syndrome were reviewed. The variation was observed in seven patients. We conclude that any operation for Wartenberg's syndrome should include a thorough investigation of the site where the radial sensory nerve emerges from under the fascia and, if the nerve emerges through a split brachioradialis tendon, the anomalous tendon slip should be divided.

The endoscopic diagnosis and possible treatment of nerve root avulsions in the management of brachial plexus injuries.

The spinal cord, dorsal rootlets, and ventral rootlets at the cervical level were visualized by endoscopy in ten goats. It is currently possible to visualize and document avulsed rootlets. With refinement in techniques and instruments, it will be possible to perform repairs, transfers or implantation of avulsed rootlets in the brachial plexus.

Intraoperative spinal root stimulation to detect most proximal site of leprous ulnar neuritis.

In 10 patients with leprous ulnar neuritis, we investigated the most proximal site of lesion in the affected nerves. Spinal roots C8 and T1 were stimulated intraoperatively to evoke efferent mixed compound nerve action potentials which were recorded from the exposed ulnar nerves. The site at which amplitudes reached a maximum was considered the most proximal site of lesion. Nerve damage was found far proximally from the thickened segments in otherwise inconspicuous sections. Epineuriotomy within these apparently unaffected segments revealed fibrosis of the interfascicular epineurium in 9 patients, which is an indication for microsurgical interfascicular neurolysis.

Superficial branch of the radial nerve emerging between two slips of a split brachioradialis muscle tendon: a variation of possible clinical relevance.

One hundred and fifty upper extremities of 75 nonrandomized human cadavers were dissected to study the topographical relationship between the brachioradialis muscle tendon (BRMT) and the superficial branch of the radial nerve (SBRN). A split BRMT was found in nine arms, while in five of those nine arms the SBRN emerged from under the brachioradialis muscle between the two slips of a divided BRMT to become superficial. This topographical relationship is mentioned sparsely in very old literature, yet its frequency has not been studied before. Further clinical investigations should be undertaken to study the clinical relevance of the above-mentioned topographical relationship.

Sensory recovery in myocutaneous, noninnervated free flaps: a morphologic, immunohistochemical, and electron microscopic study.

The aim of this study was to clarify the following questions: (1) Do newly sprouting axons use the empty neurilemmal sheaths of a flap as conduits? (2) To what extent can sensibility recover? (3) Does sensory recovery occur at the margins of the flap or at its center? (4) Does chemotaxis influence the regeneration process? In 16 free myocutaneous flaps (12 latissimus dorsi, 4 rectus abdominis) we investigated pain (pinprick), constant touch, temperature, 30- and 256-Hz vibration, and static and moving two-point discrimination between 1 1/2 and 8 years after surgery. Four flaps were anesthetic, eight recovered partly, and four had six or more modalities present all over the flap; six of ten flaps with poor recovery showed better sensitivity close to the anastomosis. Nine patients agreed to have two punch biopsies (6 mm) taken from their flaps (seven from areas with different degrees of sensory recovery and two from the center and the periphery when recovery was homogeneous). Biopsies from the areas with better sensory recovery showed slightly more nerves than the other punches in five instances, showed no difference between the two biopsies in one instance, and seemed to have more nerves in the biopsy from the area with less recovery in the last instance. The two pairs of biopsies from the homogeneously recovered flaps showed similar amounts of nerves. S-100 protein-positive neural structures (Schwann cells) were found in 13 biopsies, and neuron-specific enolase-positive nerve fibers (nerve axons) were found in 10 biopsies. Electron microscopy showed mainly unmyelinated fibers, always adjacent to vessels and sometimes with regenerative phenomena. We believe that sprouting axons probably grow into a flap attracted by chemotaxis from hair follicles, the basement membrane, and the laminin contained in the sheath. We recommend maximum scar excision at the recipient site to enhance sensory recovery in flaps. We conclude that (1) the sprouting axons primarily use the empty neurilemal sheaths as conduits, (2) sensory recovery can reach two-point discrimination equal to the donor site of the flap, and (3) sensory recovery occurs mainly from the margin of the flap but also from the bed.

Anticoagulants, antiaggregants or nothing following carotid endarterectomy?

Carotid endarterectomy (TEA) has proven to be beneficial for symptomatic patients. Anticoagulation (AC) and antiplatelet therapy (ASA) have been shown to prolong life following vascular surgery in patients with occlusive arterial disease (PAOD). To determine whether ASA or AC prolong life after TEA, retrospective analysis was undertaken, since cerebral haemorrhage is associated with the use of both drugs, especially AC. Between 1979-1986, 328 patients with stenotic lesions of the carotid bifurcation were operated upon electively. Patient survival and causes of death were the primary end points of the analysis. Recent data were obtained from the Austrian Central Bureau of Statistics. Cumulative survival rates were calculated by Kaplan-Meier estimation and differences determined by Breslow and Mantel tests. 36 patients were on AC, 157 on ASA and 135 remained without medication (0-group). Since the common risk factors in PAOD were unevenly distributed between groups, a stepwise Cox regression model was applied which revealed age (p < 0.01), cardiac pathology (p < 0.01) and diabetes (p < 0.05) as relevant for survival. Therefore, ASA patients and 0-group patients were selected and matched, employing the aforementioned prognostic criteria, and compared to the patients on long-term AC for various indications (vein bypass surgery, myocardial infarction, pulmonary embolism; i.e. data-matching). The median postoperative survival was 7.72 years for ASA and 8.48 years for AC, compared to 6.07 years for the 0-group (p = 0.0095 Breslow, p = 0.477 Mantel). There was no significant difference between AC and ASA treated patients. Irrespective of medication, the causes of death were well balanced, and no higher incidence of intracerebral haemorrhage was detected.(ABSTRACT TRUNCATED AT 250 WORDS)