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Biomedical subjects

T Menovsky

Publications and source records attributed to T Menovsky.

At least 19 recordsLinked to original sources
PubMed2003

Peri-operative levels of s-100 protein in serum: marker for surgical manipulation and postoperative complications.

Although minimally invasive neurosurgical techniques are highly sophisticated nowadays, almost any operative procedure causes an inevitable surgical trauma to the brain. As a consequence unfavorable functional outcomes are not rare. Intraoperative biochemical monitoring can be helpful first to detect but also to prevent brain damage. We investigated if serum S-100 protein (S-100) levels are a reliable marker for the extent of acute cerebral damage caused by surgical trauma or postoperative complication. S-100 is present in the cytosol of glial cells. This protein leaks into the extracellular space after cell damage and can be detected both in the cerebrospinal fluid (CSF) and serum. To determine S-100 protein levels, serum samples from 20 patients with various intracranial tumors were collected before surgery, and at one day, as well as at seven days after surgery. It was hypothesised that the size of the tumor-brain contact surface (TBCS) was closely related to the dimension of the surgical trauma. TBCS was measured from radiological imaging. The pre- and postoperative (day 1 and day 7) clinical condition of each patient was assessed. The S-100 levels were correlated with the TBCS and the clinical condition. Levels of S-100 on day 1 and day 7 were significantly higher as compared with levels on day 0 ( p = 0.02, respectively p = 0.01). There was a significant relationship between rise of S-100 level and worsening of clinical condition between day 0 and day 1 ( p = 0.001). Also a significant positive relationship between TBCS and the level of S-100 could be found on day 1 and on day 7 ( R = 0.71, p = 0.0009, respectively R = 0.73, p = 0.004). Furthermore, a significant relationship between the rise of S-100 level between day 0 and day 1, as well as between day 0 and day 7, and TBCS could be documented ( R = 0.61, p = 0.01, respectively R = 0.64, p = 0.005). In conclusion, serum S-100 levels are a reliable marker for acute or recent CNS damage caused by neurosurgical manipulation or as a result of secondary postoperative complications. Therefore, intraoperative monitoring of serum S-100 levels seems very promising. In such a setting the negative effects of surgical manipulation can be measured instantaneously, which should bring the neurosurgeon to change his strategy. As a consequence the surgical trauma can be minimized and functional outcome can be optimized.

Adult↗
PubMed2002

Coiling of saccular basilar trunk aneurysms.

We reviewed the selective endosaccular coiling of eight consecutive patients with saccular basilar trunk aneurysms, seven after subarachnoid haemorrhage (SAH). All aneurysms could be coiled in a mean procedure time of 61 min. There were no procedure-related complications, but one patient died of vasospasm following the SAH. The remaining seven had a good outcome, and five of seven aneurysms were completely occluded with a stable result on follow-up angiography. Compaction of the coils occurred in one very large aneurysm necessitating additional coiling. One patient with a giant, partially thrombosed aneurysm was coiled four times in a 3-year period to obtain a satisfactory anatomical result.

Basilar Artery↗
PubMed2001

Intraoperative values of S-100 protein, myelin basic protein, lactate, and albumin in the CSF and serum of neurosurgical patients.

OBJECTIVES: To assess the concentrations of S-100 protein, myelin basic protein (MBP), and lactate, and the (CSF)/serum albumin ratio (Qalb) during intracranial neurosurgical procedures. METHODS: Samples of CSF from 91 patients with various CNS diseases were obtained by aspiration of cisternal CSF at the beginning of surgery (before starting surgical manipulation of the brain) and concentrations of S-100 protein, MBP, and lactate, and Qalb were determined. At the same time blood was sampled for determination of serum S-100 protein concentration. Patients were divided into three groups according to the aetiology of their CNS disease (intracranial haemorrhage, n=11; benign intracranial mass lesion, n=52; malignant neoplastic disease, n=28). Radiological and intraoperative characteristics were documented. RESULTS: In each of these three groups median values of all four CSF variables measured were raised. The occurrence of brain oedema and a midline shift correlated significantly with raised concentrations of MBP and Qalb. Breaching of the arachnoid layer, documented at surgery for benign lesions, correlated with higher concentrations of MBP, lactate, CSF S-100 protein, and Qalb. CONCLUSIONS: Intraoperative values of S-100 protein, MBP, lactate, and Qalb are increased in patients with intracranial haemorrhage, benign intracranial mass lesion, and malignant neoplastic disease. Breaching of the arachnoid layer and oedema is associated with higher concentrations of some of the aforementioned proteins. These biochemical data can serve as a basis for further research into CSF specific proteins.

Adolescent↗
PubMed2001

Laser, fibrin glue, or suture repair of peripheral nerves: a comparative functional, histological, and morphometric study in the rat sciatic nerve.

OBJECT: This study was undertaken to evaluate CO2 laser-assisted nerve repair and compare it with nerve repair performed with fibrin glue or absorbable sutures. METHODS: In eight rats, the sciatic nerve was sharply transected and approximated using two 10-0 absorbable sutures and then fused by means of CO2 milliwatt laser welding (power 100 mW, exposure time 1 second per pulse, spot size 320 microm), with the addition of a protein solder (bovine albumin) to reinforce the repair site. The control groups consisted of eight rats in which the nerves were approximated with two 10-0 absorbable sutures and subsequently glued using a fibrin sealant (Tissucol), and eight rats in which the nerves were repaired using conventional microsurgical sutures (four to six 10-0 sutures in the perineurium or epineurium). Evaluation was performed 16 weeks postsurgery and included the toe-spreading test and light microscopy and morphometric assessment. The motor function of the nerves in all groups showed gradual improvement with time. At 16 weeks, the motor function was approximately 60% of the normal function, and there were no significant differences among the groups. On histological studies, all nerves revealed various degrees of axonal regeneration, with myelinated fibers in the distal nerve segments. There were slight differences in favor of the group treated with laser repair, in terms of wound healing at the repair site. In all groups, the number of axons distal to the repair site was higher compared with those proximal, but the axon diameter was significantly less than that in control nerves (p < 0.05). There were no significant differences in the number, density, or diameter of the axons in the proximal or distal nerve segments among the three nerve repair groups (p < 0.05), although there was a trend toward more and thicker myelinated axons in the distal segments of the laser-repaired nerves. CONCLUSIONS: It was found that CO2 laser-assisted nerve repair with soldering is at least equal to fibrin glue and suture repair in effectiveness in a rodent model of sciatic nerve repair.

Animals↗
PubMed2000

Effect of CO(2)-Milliwatt laser on peripheral nerves: part II. A histological and functional study.

In order to further explore the role of laser for microneural repair, the early and late effects of CO(2) laser irradiation on intact rat sciatic nerves were investigated. A total of 48 rat sciatic nerves were exposed to 100-mW laser power with a pulse duration of 1.0 s and a spot size of 320 microm. In one-half of the nerves, albumin solder was applied to the nerve followed by laser irradiation. The results were evaluated up to 94 days after surgery with functional toe-spreading test, and light and transmission electron microscopy. Irradiation of the nerve resulted in almost no deficit in the motor function. A subperineurial degeneration of myelinated and unmyelinated axons is observed in the first 2 weeks after laser irradiation, while the central part of the nerve remains undamaged. The degeneration is followed by axonal regeneration with subsequent maturation of nerve fibres in time. No excessive intraneural or extraneural scarring was seen. In the soldered nerves, the solder elicits an inflammatory reaction upon the epineurium in the first week after irradiation. By week 1, the solder is completely absorbed. After 2 weeks, the inflammatory reaction ceases and by week 4, no residual reaction is seen. At 12 weeks, only minimally disarranged epineurium is seen with otherwise normal neural architecture. In conclusion, CO(2) laser irradiation at 100 mW with pulses of 1.0 s has no long term negative effects on nerve function and morphology. Therefore, these laser settings can be safely applied for laser-assisted nerve repair.

Animals↗
PubMed2000

A human skull cast model for training of intracranial microneurosurgical skills.

Skillful microsurgical techniques such as microvascular anastomosis and repair of nerves require dedicated and extensive laboratory training. Human microneurosurgery poses several additional technical difficulties, as the intracranial procedures are often performed through a narrow operative space at a considerable length, using knee-bend instruments. This article presents a laboratory model to simulate microneurosurgical procedures in humans. A human skull cast model made from plaster is cut such that, when placed on a operating table, it represents a standard position of a pterional approach and that the point of operation is at the same depth as the hypothetical circle of Willis. A standard pterional opening is made in de skull cast and the model is placed over the rat. Subsequently, all surgical procedures starting from tissue preparation to performing an arterial, venous, and/or nerve repair are performed with the cast over the rat using microneurosurgical knee-bent instruments and a surgical microscope. Microsurgical procedures such as end-to-end vessel anastomosis and nerve repair are technically much more challenging and difficult to execute when performed through the pterional opening of the human skull cast than without the cast model. Moreover, the cast model useful in training microsurgical techniques performed with long knee-bend instruments. It is concluded that the skull cast model represents a useful method to train intracranial microneurosurgical blood vessel anastomosis and nerve repair.

Humans↗
PubMed2000

CO2 and Nd:YAG laser-assisted nerve repair: a study of bonding strength and thermal damage.

To improve the laser welding procedure, a comparative study was undertaken to investigate the acute bonding strength and the thermal damage following CO2 and Nd:YAG laser-assisted nerve repair, performed with and without the use of blood and/or albumin as a solder. The strongest welds were produced with the CO2 laser using albumin as a solder. Thermal damage was minimal with the CO2 laser, whereas the damage with the Nd:YAG laser was substantial. The high bonding strength combined with minimal thermal damage of the nerve following repair with the CO2 laser with the use of albumin justify further investigations using this technique in in vivo studies.

Animals↗
PubMed1999

Effect of a modified Nd:YAG laser technique on neuroma formation: An experimental study in rat sciatic nerve.

BACKGROUND AND OBJECTIVES: Traumatic transection of a peripheral nerve is inherently associated with the development of neuroma at the end of the proximal stump, often leading to therapy-resistant pain. This study was designed to evaluate whether the neodymium:yttrium aluminum garnet (Nd:YAG) laser could prevent neuroma formation after neurectomy. STUDY DESIGN/MATERIALS AND METHODS: The sciatic nerves of 14 rats were diffuse coagulated by defocused Nd:YAG laser (12 W power), and subsequently transected with additional focused laser energy. The control group consisted of contralateral nerves transected by microscissors. The nerves were reexposed at different time intervals up to 9 weeks after surgery, and evaluation consisted of macroscopy, and light and transmission electron microscopy. RESULTS: True neuroma formation could not be observed after laser transection, and only five nerves formed a neuromatous bulb, with minimal adhesions to surrounding tissue. Microscissor transection resulted in widespread amputation neuromas, consisting of regenerating axons and connective tissue, and nervous tissue regenerating into surrounding tissue. Laser-transected nerves showed degenerative changes of the axons and myelin, while proliferation of Schwann cells could not be observed. No outgrowth of axons could be observed outside the coagulated proximal stump. An epi/perineurial layer was present, covering the nerve stumps. Microscissor-transected nerves showed proliferation of fibroblasts and Schwann cells, forming minifascicles, and vigorous outgrowth of axons into the tissue and even into the distal nerve stump. CONCLUSIONS: Within the limitations of this study it is concluded that the formation of amputation neuromas is suppressed by Nd:YAG laser application by thermal coagulation of the nerve and suppression of Schwann-cell proliferation.

Animals↗
PubMed1999

Surgical approach and histoanatomical aspects of the oculomotor nerve in rats.

The surgical approach and some histoanatomical characteristics of the intracavernous portion of the oculomotor nerve are described. Moreover, some perioperative precautions for intracranial surgical procedures in the rat are reported and the suitability of the rat as a model for studying intracranial nerve regeneration is discussed. With the data provided, this model of oculomotor nerve approach can be used to study various aspects of intracranial nerve regeneration.

Animals↗
PubMed1999

End-to-end versus peripheral nerve graft repair of the oculomotor nerve in rats: A comparative histological and morphometric study.

A comparative study was undertaken to evaluate end-to-end versus peripheral nerve graft repair in cranial nerve reconstruction. In 14 rats, the oculomotor nerve was sharply transected in the cavernous sinus and repaired either by end-to-end coaptation (n = 7) or by interposition of a peripheral nerve graft (n = 7). The results were evaluated 16 weeks after surgery by light and transmission electron microsurgery and by morphometric analysis. The degree of neuroma formation, fibrosis, and axonal disorganisation at the repair site was the same for both groups. Histologically, both end-to-end and graft repair groups revealed various degrees of axonal regeneration with myelinated nerve fibres in the distal nerve segments. In both groups, the number of nerve fibres distal to the repair site was increased compared to proximal to the repair (P < 0.001) but myelinated axon diameter was significantly less than that of control nerves (P < 0.001). No difference existed between the two repair groups in terms of mean myelinated axonal diameter. However, the number and density of myelinated axons was statistically greater in the graft group (P < 0.05). In conclusion, despite the disadvantage of two repair sites, peripheral nerve grafting results in equal or slightly superior axonal regeneration compared to an end-to-end repair in the rodent model of intracranial oculomotor nerve reconstruction. We speculate that this may be due to the structure of the peripheral nerve graft.

Animals↗
PubMed1999

On the mechanism of transient postoperative deficit of cranial nerves.

BACKGROUND: Transient cranial nerve deficit is a common postoperative complication after surgery at the cranial base. In this type of surgery, the cranial nerves are often not macroscopically damaged or transected, but more or less manipulated during surgery. In this article, the cellular mechanisms of postoperative cranial nerve deficit are reviewed. METHODS: Experimental and clinical papers concerning cranial and peripheral nerve damage during surgery were critically reviewed. RESULTS: There are definite differences in the anatomical and histological structure between peripheral and intracranial nerves, which make the latter much more prone to intraoperative damage. Several pathological mechanisms are responsible for postoperative deficit, such as segmental demyelination of the nerve, comprised microcirculation within the nerve, postoperative edema, and "synaptic stripping" around the cell bodies of the affected neurons, which can be regarded as a regenerative response of the nervous system. CONCLUSIONS: Several cellular mechanisms are responsible for postoperative cranial nerve deficit after skull base surgery. Understanding these mechanisms is important for all surgeons involved in the treatment of skull base lesions.

Cranial Nerve Diseases↗
PubMed1999

Endoscope-assisted supraorbital craniotomy for lesions of the interpeduncular fossa.

OBJECTIVE: The supraorbital approach is well accepted for lesions in the anterior fossa, the sellar region, and the anterior circle of Willis. However, the usefulness of this approach has not yet been elucidated for lesions in the interpeduncular fossa. The technique of an endoscope-assisted, ipsi- and contralateral supraorbital approach to lesions within the interpeduncular fossa is described, and the initial results are reported. METHODS: A small supraorbital craniotomy, using an eyebrow incision, was performed in each of seven patients who were operated on for different types of lesions in the interpeduncular fossa, including a neuromuscular choristoma of the oculomotor nerve, a retrosellar epidermoid tumor, and five aneurysms (two of the basilar artery tip, two at the offspring of the superior cerebellar artery, and one fusiform arterial widening of the basilar artery apex). The surgical approach, its indications and limitations, and the additional value of an endoscope are outlined. RESULTS: All lesions could be easily reached and well visualized through this approach by using an endoscope as an adjunct to the operating microscope. The saccular aneurysms all could be clipped successfully, the fusiform widening was wrapped, the epidermoid tumor was removed completely, and the choristoma was removed only partially because of brain stem invasion. The patient with the neuromuscular choristoma had persistent diabetes insipidus postoperatively, most probably caused by stretching the pituitary stalk with the endoscope. The patient with the epidermoid tumor showed a postoperative transient partial oculomotor nerve paresis at the side of the approach. The cosmetic results of the eyebrow incisions for this approach were excellent in all patients. CONCLUSION: Lesions in the interpeduncular fossa can be effectively treated using a supraorbital approach, which can be ipsi- or contralateral to the side of the lesion, depending on the exact location of the lesion. The use of an endoscope is essential to visualize these lesions that lie in the shadow of the sellar and parasellar anatomic structures. The major advantage over other approaches are a nearly perpendicular surgical route (although the distance is longer, which is, on the other hand, not a disadvantage), a minimized amount of dissection and brain retraction by using an endoscope through anatomic gateways, and a small surgical incision with excellent cosmetic results.

Adult↗
PubMed1999

Stabilization and accurate trimming of nerve ends: practical use of fibrin glue: technical note.

OBJECTIVE: Peripheral nerve transection usually results in protrusion of the endoneurial contents ("mushrooming"). Trimming of the nerve ends before repair is often necessary to achieve cut nerve end planes. In this technical report, we describe a technique for stabilization and accurate trimming of nerve ends using fibrin glue. SURGICAL TECHNIQUE: The nerve ends of divided peripheral nerves are coated with fibrin glue and subsequently trimmed using a razor blade before repair. RESULTS: When fibrin glue is applied, a firm layer with a rubbery consistency is formed around the nerve. This layer stabilizes the nerve ends during trimming, and a clear-cut plane of the nerve can be achieved. Moreover, the fibrin glue stabilizes the nerve ends during manipulations caused by suturing of the nerve. CONCLUSION: The technique results in easier handling of the nerve during trimming and manipulation, minimal tissue damage to the nerve, and a clear-cut plane of the nerve.

Fibrin Tissue Adhesive↗
PubMed1999

The use of Gore-Tex membrane for adhesion prevention in tethered spinal cord surgery: technical case reports.

OBJECTIVE: The incidence of retethering caused by postoperative adhesions at the repair site after initial tethered spinal cord surgery is not uncommon. To assess the effectiveness of a Gore-Tex membrane in preventing these adhesions, only clinical radiological and experimental animal evaluation has been reported. In this report, we describe two cases in which Gore-Tex membrane was implanted at the initial untethering surgery and in which we were able to confirm the real effectiveness of the Gore-Tex membrane during a second operation. METHODS: In the first patient, Gore-Tex membrane was used for dural repair in the untethering surgery of the split spinal cord malformation. Because of the suspicion of a thickened filum terminale, repeated surgery was indicated 10 months after the initial procedure. In the second patient, Gore-Tex membrane was implanted during the initial untethering surgery for a lipomyeloschisis and a dermal sinus. Because of a persistent fistula of the dermal sinus, a second operation was necessary 1 year after the first operation. RESULTS: During the repeated surgery, a thorough inspection of the implanted Gore-Tex membrane revealed no adhesions between the Gore-Tex membrane and the intradural content in both cases. CONCLUSION: We support the use of Gore-Tex membrane in the prevention of postoperative dural adhesions in the repair of spinal dysraphism.

Child, Preschool↗
PubMed1999

A modified staining method for connective tissue in semi-thin histological sections of peripheral and cranial nerves.

A simple staining method for collagen in semi-thin sections of nerves is described. This technique consists of applying basic fuchsin (0.05%) solution for 2 min. to +/- 1.25 microns plastic resin-embedded sections after routine toluidine blue staining. This staining method clearly demonstrates the amount and orientation of collagenous connective tissue in the nerve, both in transverse and longitudinal sections.

Animals↗