Spontaneous electromyographic activity during microvascular decompression in trigeminal neuralgia.

Intraoperative monitoring of spontaneous facial nerve electromyographic activity during surgery for microvascular decompression in trigeminal neuralgia was evaluated. Fifteen patients with trigeminal neuralgia underwent surgery for microvascular decompression. During the entire operation, free-running facial nerve electromyographic signals were recorded. The data were analyzed with respect to waveform patterns known from vestibular schwannoma-surgery. Special regard was given to the occurrence of A-trains that are associated with postoperative paresis in patients operated on vestibular schwannoma. The spectrum of the observed activities matched patterns known from surgery of vestibular schwannoma; even A-trains, a pattern known to be an indicator of postoperative deterioration of facial nerve function (Romstöck et al., J Neurosurg 2000;93:586-593), were seen in 3 of the 15 patients with trigeminal neuralgia. The quantity of A-trains observed was much less than it is known from patients operated on tumors of the cerebellopontine angle. None of the trigeminal neuralgia-patients experienced postoperative deterioration of facial nerve function. The present study shows that A-trains do not only occur during tumor surgery, but also during procedures with indirect manipulation of the facial nerve. They do not necessarily lead to postoperative paresis as long as certain thresholds concerning amount and length of these A-trains are not exceeded.

Preparation of the neck for microvascular reconstruction of the head and neck.

Reconstruction of congenital, developmental, or acquired head and neck defects remains a significant challenge for the oral and maxillofacial surgeon. Microvascular free tissue transfer has several advantages over nonvascularized bone grafts and pedicled soft tissue flaps that currently make it the modality of choice for the reconstruction of extirpative defects of the head and neck. Preoperative planning must include detailed attention to the technical aspects of the microvascular procedure. This includes a thorough understanding of the vascular anatomy of the patient's neck; vascular anatomy of the various flaps including pedicle lengths; and a knowledge of how to facilitate microvascular surgery in the neck and to manage complicating factors in the difficult neck.

Microvascular anastomosis training model based on a Turkey neck with perfused arteries.

OBJECTIVE: The microvascular anastomosis (MA) technique remains an important aspect of modern neurosurgical practice. Specialized training is essential for mastering the anastomosis of small vessels. To minimize animal use and to create a simple but realistic training model, we developed a pulsatile perfused arteries model based on turkey carotid arteries for microvascular anastomosis training. METHODS: Approximately 10-cm-long segments of turkey necks were used as a material to set up this model. The diameter of turkey carotid arteries at the neck level was found to be between 1 and 3 mm. Both carotid arteries on the neck segment were cannulated and incorporated into a closed circulation circuit consisting of silicone tubes and an infusion pump that provided continuous arterial-like flow and pulsation during the MA training. Tubing connection with both proximal and distal ends of the carotid arteries allowed circulatory patency during vessel clamping and anastomosis creation. Different fluids ranging from simple water to various colored solutions or even whole blood could be used for vascular perfusion in this experimental setup. Fluid output was maintained between 11 and 16 ml/min. Minimum pressure was set at 80 cm/H20, and maximum pressure was set at 160 cm/H20. Mean fluid flow through the arteries was 8 to 13 ml/min. End-to-end, end-to-side, and side-to-side MA may be performed on this model. RESULTS: This training model provides several advantages: the materials are easily obtainable and inexpensive, pulsatile flow through the arteries is realistic, the model is easy to manage, and there is no need for special facilities for animal care or anesthesia that are required for live animals. The diameter and structure of turkey carotid arteries are essentially identical to the human cortical vessels and distal branches of the superficial temporal artery. CONCLUSION: The pulsatile perfused carotid arteries model presents a realistic MA training model. It provides an inexpensive and simple setup for educational purposes. This technique can minimize live animal and anesthesia needs for MA training. Wide use of this model may enhance and popularize MA training and education.

Management of petrosal veins during microvascular decompression for trigeminal neuralgia.

OBJECTIVE: Venous compression might be the main cause of incomplete decompression and symptom recurrence after microvascular decompression (MVD) in patients with trigeminal neuralgia. Although it can be killed in most cases, cutting the vein sometimes has the potential risk arising from venous congestion. To maneuver the vein safely, we introduced a temporary occlusion test of the vein. METHODS: Among 407 consecutive MVD cases, 48 (11.8%) offending and 157 block veins were encountered. The vein was cut directly in 147 (71.7%). Owing to the potential risk following killing of the vein, 58 (28.3%) patients underwent venous occlusion test with neurophysiologic monitoring during the operation. The temporal occlusion should be ceased immediately as soon as any changes in brainstem auditory evoked potential (BAEP) or trigeminal evoked potential (TEP) wave figuration turn up; otherwise, it would last for 15 minutes. RESULTS: The occlusion test was negative in 53 (91.4%), while positive in five patients (8.6%). According to the results, we cut the vein in test-negative patients, which made the operation easy and offered a satisfactory decompression. Among the five positive cases, the vein was finally saved in two and cut in three cases. Yet, all the three patients developed a severe ipsilateral cerebellar edema and brainstem shift after the vein was sacrificed. Despite those patients were reoperated on immediately for posterior fossa decompression, they remained equilibrium disorder with numbness in ipsilateral face and mind hemiparesis in contralateral extremities post-operatively. The residual two patients had an incomplete pain relief. CONCLUSION: This venous occlusion test could help the surgeon in making a right decision before manipulation of the petrosal veins during MVD.

Use of hyperosmotic chemical agent to improve the laser treatment of cutaneous vascular lesions.

A method is presented for decreasing radiant exposures required for photocoagulation of cutaneous blood vessels using a hyperosmotic agent applied to skin prior to laser irradiation. The 50% probability for a given radiant exposure (RE50) to result in photocoagulation of vessels classified by type (arteriole, venule) and diameter was determined following direct (subcutaneous) laser irradiation of 84 vessels in a dorsal skin preparation pretreated with glycerol. Values were compared against results without glycerol pretreatment. A second set of experiments involved irradiation of blood vessels through the skin from the epidermal surface after application of glycerol. Subcutaneous RE50s for vessels treated with glycerol were typically several factors lower than untreated vessels. For example, arterioles in the 80- to 110-microm-diam range in untreated skin had RE50 values approximately 12 J/cm(2), compared to approximately 2 J/cm(2) in glycerol-treated cases. Results from epidermal irradiations also indicate that pretreatment with glycerol decreases radiant exposures required for photocoagulation. Vessels were successfully coagulated from the epidermal side in glycerol-treated samples using radiant exposures ranging from 1.6 J/cm(2) to 5 Jcm(2), compared to the 12 to >16 J/cm(2) range for control cases. We believe that this method could be a powerful technique for reducing the radiant exposures required for vessel photocoagulation.

Desirudin reduces the rate of microvenous thrombosis in a rat model.

OBJECTIVES: In an effort to evaluate pharmacologic agents for optimal anticoagulant prophylaxis in patients undergoing free tissue transfer, we evaluated the efficacy of desirudin (Canyon Pharmaceuticals, Hunt Valley, MD), a recombinant hirudin that acts as a direct thrombin inhibitor, using a rat model of microvenous thrombosis. STUDY DESIGN: Randomized, blinded study using an in vivo rat model of microvenous failure. METHODS: Thirty-two rats received either desirudin or saline in a randomized, blinded fashion 30 minutes prior to performance of a standardized thrombogenic procedure on rat femoral veins. Bleeding time, vessel patency, and presence of clot within the anastomosis were subsequently assessed. Appropriate statistical analyses were then performed. RESULTS: There was a significant increase in vessel patency in rats treated preoperatively with desirudin compared to controls receiving saline (96.9% vs. 53.1%, P < .001). In evaluating patent vessels for non-occluding clot, 41.2% of control rats had non-obstructive clot at the site of anastomosis, versus 3.2% of rats treated with desirudin (P = .002). Bleeding times were longer in desirudin-treated rats than those that received saline (7.17 +/- 3 minutes vs. 5.15 +/- 1.2 minutes, P = .027). CONCLUSIONS: The use of preoperative desirudin increases the rate of microvascular anastomotic patency, decreases the occurrence of non-occluding clot, and increases bleeding time in an in vivo rat model, indicating potential efficacy in patients undergoing microvascular free tissue transfer.

Successful vascular decompression in an 11-year-old patient with trigeminal neuralgia.

CASE REPORT: We present the case of an 11-year-old boy who was suffering distinct trigeminal neuralgia. At the age of 3 years, the patient had contracted a severe Epstein-Barr virus infection and developed mild meningoencephalitis. Magnetic resonance imaging scans showed a slight enhancement in the pontomesencephalic cistern as well as a neurovascular conflict at the right trigeminal nerve. Intraoperatively, thickened fibrous tissue was found that was attached to both the trigeminal nerve and the superior cerebellar artery. Microvascular decompression using Gore Tex as tissue implant brought immediate relief. DISCUSSION: Trigeminal neuralgia in pediatric patients is very rare. We present a case of typical trigeminal neuralgia in a child, demonstrating the pathogenesis of the neurovascular conflict due to subarachnoidal adhesions after meningoencephalitis.

The thoracoacromial trunk: alternative recipient vessels in reoperative head and neck reconstructive microsurgery.

BACKGROUND: Reoperative free tissue transfer in head and neck cancer patients is often a challenging endeavor. Finding adequate recipient vessels for microvascular anastomosis can be difficult, as scar is present from previous surgery and irradiation, and the usual recipient vessels may have been damaged or sacrificed. METHODS: Seventeen consecutive cases of head and neck reconstruction with free tissue transfer using the thoracoacromial vessels as the recipient pedicle were reviewed. Clinical data were analyzed, including indication for surgery, preoperative radiation dose, previous pectoralis major myofascial flap, free flap design, operative technique, perioperative complications, and follow-up. RESULTS: Of the 17 cases of free tissue transfer using thoracoacromial vessels for anastomosis, 13 flaps were performed in 12 patients who had received double irradiation. Twelve thoracoacromial trunks used as recipient vessels were in patients with transferred pectoral myofascial flaps. Anastomotic patency was achieved in all flaps. CONCLUSIONS: The thoracoacromial trunk is a good alternative for recipient vessels in reoperative reconstructive microsurgery of the head and neck when first-line vessels are not available. This choice of vessels is feasible whether or not a pectoralis myofascial flap has previously been used.

Rates of symptom reoccurrence after endovascular therapy in subclavian artery stenosis and prevalence of subclavian artery stenosis prior to coronary artery bypass grafting.

Percutaneous transluminal angioplasty (PTA) and stenting is commonly used to treat subclavian artery stenosis (SAS). In this study, the outcomes of 43 consecutive cases, performed at one institution from October 1997 to October 2005, were analyzed. Mean stenosis was 84.41% pre-intervention and 6.83% post-intervention. Five of the procedures were angioplasty alone; 38 were angioplasty with stenting. Technical success was achieved in 42 out of 43 patients. The 30-day mortality rate was 0%. At one-month post intervention, all patients were symptom free. Ten patients redeveloped symptoms by one year. Demographic data, patient comorbidities, and indication to treat were analyzed. It was found that prior coronary intervention led to a statistically significant higher rate of symptom reoccurrence (p = 0.036). Additionally, a divergence in the rate of symptom reoccurrence based on indication to treat SAS was noted with the highest rate of symptom reoccurrence in the pre-coronary artery bypass grafting (CABG) group and the lowest rate of symptom reoccurrence in the subclavian steal syndrome (SSS) group. The coronary subclavian steal (CSS) group had an intermediate rate of symptom reoccurrence. During this time period, 1154 CABGs were performed. Flow-limiting stenosis was noted on angiography in 17 of these patients, giving pre-CABG prevalence of 1.46%.

Emergency endovascular repair of acute descending thoracic aortic dissection.

BACKGROUND: Acute descending thoracic aortic dissection is a life-threatening emergency. It is not often considered as the initial diagnosis in patients presenting with epigastric pain and could easily be missed in a busy casualty department. AIM: This case report is aimed to highlight the feasibility of the technique and the need for long-term surveillance following endovascular repair of acute thoracic aortic dissection. RESULTS: The patient presented with epigastric pain radiating to the interscapular region with a stable hemodynamic status. A computerized tomography (CT) scan demonstrated type B thoracic aortic dissection of the proximal descending thoracic aorta. A successful endovascular repair was carried out with uneventful recovery and follow-up CT scan six years after stent-grafting shows satisfactory position of the stent-graft, patent false lumen in the abdominal aorta perfusing the right kidney, and progressively enlarging diameter of the abdominal aorta. CONCLUSION: Thoracic aortic dissection should be considered as a differential diagnosis in patients presenting with epigastric and interscapular chest pain. Emergency endovascular repair of acute thoracic aortic dissection is feasible and relatively safe. Regular follow-up with CT scan is required to evaluate the long-term efficacy and identify the need for re-intervention.

Restoration of microvascular function in the infarct-related artery by intracoronary transplantation of bone marrow progenitor cells in patients with acute myocardial infarction: the Doppler Substudy of the Reinfusion of Enriched Progenitor Cells and Infarct Remodeling in Acute Myocardial Infarction (REPAIR-AMI) trial.

BACKGROUND: The Doppler Substudy of the randomized, double-blind, placebo-controlled Reinfusion of Enriched Progenitor Cells and Infarct Remodeling in Acute Myocardial Infarction (REPAIR-AMI) trial aimed to investigate the effects of intracoronary infusion of bone marrow-derived progenitor cells (BMCs) on coronary blood flow regulation in patients with reperfused acute myocardial infarction. METHODS AND RESULTS: In a total of 58 patients (BMC group, n=30; placebo group, n=28), coronary flow reserve (CFR) in the infarct artery and a reference vessel was assessed by intracoronary Doppler at the time of study therapy (4.2+/-0.1 days after acute myocardial infarction) and at the 4-month follow-up. Initial CFR was reduced in the infarct artery compared with the reference vessel in both groups (BMC: 2.0+/-0.1 versus 2.9+/-0.2, P<0.05; placebo: 1.9+/-0.1 versus 2.8+/-0.2; P<0.05). At the 4-month follow-up, CFR in the infarct artery had slightly improved in the placebo group (+0.88+/-0.18; P<0.001 versus initial) but was markedly increased by 90% (+1.80+/-0.25; P=0.005 versus placebo) in BMC-treated patients, resulting in a normalization of CFR (3.8+/-0.2; P<0.001 versus initial and placebo at 4 months). In the infarct vessel, adenosine-induced minimal vascular resistance index declined slightly in the placebo group (from 1.77+/-0.12 to 1.52+/-0.15 mm Hg x s/cm; P<0.05) but considerably decreased by -29+/-6% in the BMC group (from 1.86+/-0.19 to 1.20+/-0.12 mm Hg x s/cm; P<0.05 versus initial and placebo at 4 months). CONCLUSIONS: Intracoronary BMC therapy after acute myocardial infarction restores microvascular function of the infarct-related artery, which is associated with a significant improvement in maximal vascular conductance capacity. These data provide clinical proof of concept that progenitor cell transplantation promotes vascular repair.

Superior petrosal vein in trigeminal neuralgia.

During microvascular decompression procedure for trigeminal neuralgia, surgical attention is mainly focused at the neurovascular conflict at trigeminal root entry zone. However, many major complications of this surgery are often related to venous structures in the posterior fossa, including the venous sinuses and the superior petrosal vein(s). The author reviews surgical anatomy of the superior petrosal vein, highlights important surgical steps related to its microsurgical dissection and discusses avoidance of complications, as well as their management during microvascular decompressive surgery in this region. The discussion is mainly focused on the surgical anatomy of the superior petrosal vein along with its significance during surgery and not on the neurovascular relationships of the trigeminal nerve or aetio-pathogenesis of trigeminal neuralgia.

Current concepts of microvascular reconstruction for limb salvage in electrical burn injuries.

BACKGROUND: Microvascular reconstruction is rarely indicated in burn injuries. As the versatility and variability of free flaps have increased significantly during recent years so, the indications for this procedure have been expanded for limb salvage after electrical injuries. METHODS: We report retrospectively the results of 26 free flaps for extremity reconstruction in 19 patients suffering from severe electrical burn injuries. Nine different free flap types were used. On the basis of this experience we were able to establish reconstructive principles in electrical injuries pertinent to the timing of reconstruction procedures. RESULTS: Early coverage with muscular flaps was the most frequently used type of reconstruction. At a later stage of the treatment course reconstruction with cutaneous or fascial flaps was the preferred method; for the reconstruction of complex or multistructural defects (n=3) combined 'chimeric' flaps were used. Overall, the flap failure rate was 15% (n=4). Interestingly, there was a relationship between flap failure rate and timing of the procedure. All the flap failures occurred within 5-21 days after trauma. No flap failure occurred during secondary reconstruction. CONCLUSIONS: Our data demonstrate that electrical burn injuries are distinct entities requiring individual reconstructive solutions for limb salvage. Even if our flap failure rate is relatively high it should not be forgotten that this type of reconstruction represents an opportunity for limb salvage as opposed to early amputation.

Preoperative simulation for microvascular decompression in patients with idiopathic trigeminal neuralgia: visualization with three-dimensional magnetic resonance cisternogram and angiogram fusion imaging.

OBJECTIVE: Precise assessment of the complex nerve-vessel relationship at the root entry zone of the trigeminal nerve is useful for planning microvascular decompression in patients with idiopathic trigeminal neuralgia. We have applied a fusion imaging technique of three-dimensional (3-D) magnetic resonance cisternography and co-registered 3-D magnetic resonance angiography (MRA) that allows virtual reality for the preoperative simulation of the neurovascular conflict at the trigeminal nerve root entry zone. METHODS: Fusion images of 3-D magnetic resonance cisternograms and angiograms were reconstructed by a perspective volume-rendering algorithm from the volumetric data sets of magnetic resonance cisternography, obtained by a T2-weighted 3-D fast spin echo sequence, and co-registered MRA, by a 3-D time-of-flight sequence. Consecutive series of 12 patients with idiopathic trigeminal neuralgia were studied with fusion 3-D magnetic resonance cisternogram and MRA in the preoperative assessment for the microvascular decompression of the affected trigeminal nerve. RESULTS: The complex anatomical relationship of the offending vessels to the trigeminal nerve root entry zone was depicted on the fusion 3-D magnetic resonance cisternogram and MRA. The presence of offending vessels and compressive site of neurovascular conflict was assessed from the various viewpoints within the cistern and was presumed by the preoperative simulation through the surgical access (surgeon's-eye view). The blinded surgical trajectory was discerned by the virtual image through the opposite direction projected from above (bird's-eye view). The 3-D visualization of the nerve-vessel relationship with fusion images was consistent with the intraoperative trajectory and findings. CONCLUSION: Fusion imaging of 3-D magnetic resonance cisternogram and MRA may prove a useful adjunct for the diagnosis and decision-making process to execute the microvascular decompression in patients with idiopathic trigeminal neuralgia.

Effects of 532 nm pulsed-KTP laser parameters on vessel ablation in the avian chorioallantoic membrane: implications for vocal fold mucosa.

OBJECTIVES: Selective vascular ablation (photoangiolysis) using pulsed lasers that target hemoglobin is an effective treatment strategy for many vocal fold lesions. However, vessel rupture with extravasation of blood reduces selectivity for vessels, which is frequently observed with the 0.45-ms, 585-nm pulsed dye laser. Previous studies have shown that vessel rupture is the result of vaporization of blood, an event that varies with laser pulse width and pulse fluence (energy per unit area). Clinical observations using a 532-nm wavelength pulsed potassium-titanyl-phosphate (KTP) laser revealed less laser-induced hemorrhage than the pulsed dye laser. This study investigated settings for the pulsed KTP laser to achieve selective vessel destruction without rupture using the avian chorioallantoic membrane under conditions similar to flexible laryngoscopic delivery of the laser in clinical practice. STUDY DESIGN: The chick chorioallantoic membrane offers convenient access to many small blood vessels similar in size to those targeted in human vocal fold. Using a 532-nm pulsed KTP laser, pulse width, pulse energy, and working distance from the optical delivery fiber were varied to assess influence on the ability to achieve vessel coagulation without vessel wall rupture. METHODS: Third-order vessels (n = 135) were irradiated: Energy (471-550 mJ), pulse width (10, 15, 30 ms), and fiber-to-tissue distance (1 mm, 3 mm) were varied systematically. RESULTS: Selective vessel destruction without vessel wall rupture was more often achieved by increasing pulse width, increasing the fiber-to-tissue distance, and decreasing energy. Vessel destruction without rupture was consistently achieved using 15- or 30-ms pulses with a fiber-to-tissue distance of 3 mm (pulse fluence of 13-16 J/cm). CONCLUSIONS: This study substantiates our clinical observation that a 532-nm pulsed KTP laser was effective for ablating microcirculation while minimizing vessel wall rupture and hemorrhage.

Congenital vascular malformations: general treatment principles.

The era where surgical excision alone was the sole treatment of venous malformation (VM) is now over. A multidisciplinary approach that utilizes both traditional surgical therapy and endovascular therapy is now the standard of care. Endovascular therapy utilizing primarily both embolization therapy and sclerotherapy is the treatment of choice for surgically 'inaccessible' VM lesions. Surgical therapy of VM lesions has been shown to be more effective when combined with supplemental endovascular therapy.