Name: microvascular decompression: salient surgical principles and technical nuances
Uploaded: 2011-07-05T13:00:00
Duration: 10 min 35 s
Description: Watch this Scientific Journal Video about Microvascular Decompression: Salient Surgical Principles and Technical Nuances at JoVE.com

1. Positioning
<ol>
 <li>Positioning is an integral component of microvascular decompression. Following induction of anesthesia, the patient is placed in pins while on the operating room table and moved to the lateral park bench position with side of the desired MVD placed up. Of note, JSN prefers to insert a lumbar drain prior to the procedure to allow greater control of intra-op drainage of CSF and cerebellar relaxation (the drain is then removed when the patient is discharged, often on POD2).</li>
 <li>All pressure points are padded and an axillary roll is placed. The patient's chest and hips are taped securely to the table to allow rotation of the table, if necessary, later in the case. The patient's shoulder is taped down for purposes of visualization. The head is rotated approximately 10-15 degrees away from the affected side and the neck is flexed slightly so that the planned surgical trajectory is now almost orthogonal to the floor. The vertex is tilted slightly down. Special attention is made to ensure that there no pathologic compression of venous drainage from the head. Specifically, there should be room for at least two finger breadths between the mandible and upper thorax. Head rotation should not exceed 30 degrees.</li>
 <li>c. The body is secured prior to three-point head fixation. Electrophysiologic monitoring (brainstem auditory evoked response and facial nerve monitoring) is then secured. Stealth navigation, if used, is registered.</li>
</ol>
2. Incision
<ol>
 <li>Prior to prepping and draping, external landmarks are assessed. It is helpful to draw the inion-meatal line with an indelible marker. The iniomeatal line is drawn out first with an indelible marker. This dotted line represents the superficial representation of the location of the transverse sinus. Next, a dotted line is drawn overlying the course of the digastric groove. The portion of this line inferior to the iniomeatal line represents a superficial representation of the location of the sigmoid sinus.</li>
 <li>A curvilinear incision is drawn out approximately two fingerbreadths behind the pinna for the length of the ear. The patient is prepped and draped in the usual fashion.</li>
 <li>Using a scalpel, the aforementioned incision is deepened. Dissection is carried down to the bone using a scalpel and monopolar cautery. Self-retaining retractors are placed.</li>
</ol>
3. Craniotomy and dural opening
<ol>
 <li>With the superficial representation of the junction of the transverse and sigmoid sinuses in mind, drilling is initiated.</li>
 <li>PEK prefers to drill the bone away to expose the transverse-sigmoid junction. A 3-cm craniectomy defect is usually created for access to the CP angle. This method avoids the possible risk posed by use of a drill with a footplate adjacent to the venous sinuses, potentially resulting in a dural sinus laceration.</li>
 <li>JSN prefers to use a perforator drill for burr hole placement at the level of the transverse-sigmoid junction. Following this, a 3-cm craniotomy bone flap is created and set aside for replacement at the end of the case. The drill is then used to expose the remainder of the transverse and sigmoid sinuses. This method allows for replacement of the bone flap following the microvascular decompression.</li>
 <li>Once the transverse and sigmoid sinuses have been exposed extradurally, the bone edges are waxed thoroughly. It is important to drill far enough laterally to allow proper dural reflection and visualization. When the mastoid air cells are encountered, they are vigorously waxed.</li>
 <li>The dura is opened in a stellate fashion. The dural leaves are tacked up using 4-0 Nurolon and the dural incision is taken as close to the transverse-sigmoid junction as possible. This allows visualization of a corridor directly adjacent to the junction of the tentorium and petrous temporal bone.</li>
</ol>
4. Exposure of the cerebellopontine angle
<ol>
 <li>After the dura has been reflected and sutured, a Leyla retractor is placed with telfa underlying the retractor. The cerebellum is elevated and gently retracted medially. Using suction and bipolar electrocautery, CSF is allowed to egress-resulting in gentle relaxation of the cerebellum.</li>
 <li>With the cerebellum now having fallen away from the petro-tentorial junction, the retractor is advanced with further gentle elevation of the cerebellum. The superior petrosal vein complex is taken when necessary. When the petrosal vein is sacrificed, coagulation with bipolar cautery is followed by partially division with microscissors. The vessel is then further coagulated and then fully transected to ensure there is no hemorrhage following vessel ligation.</li>
 <li>As "the corner is turned" and the cerebellopontine angle is exposed, the VII-VIII nerve complex is visualized first. During this exposure, vigilant attention is given to BAER (brainstem auditory evoked response) and facial nerve monitoring to guard against retraction injury. Superior and medial to the VII-VIII nerve complex, the trigeminal nerve is then visualized.</li>
</ol>
5. Decompression of the trigeminal nerve
<ol>
 <li>Microscissors are used to open the arachnoid around the trigeminal nerve. Sharp dissection is necessary so that the nerve and superior cerebellar artery (SCA) can be inspected circumferentially. Inspection of the trigeminal nerve begins at the site of brainstem exit and proceeds laterally.</li>
 <li>The most common vessel found in trigeminal neuralgia is a rostroventral loop of the SCA1. This vessel was the causal agent of compression in 53% of patients in this series.</li>
 <li>After the causative vessel is identified, dissected, and freed, the vessel loop is mobilized away from the nerve. A small piece of Teflon is then placed underneath the vessel-elevating it off the trigeminal nerve.</li>
 <li>Following decompression, the nerve is reexamined on all sides to be certain that no additional compressing vessels are present.</li>
</ol>
6. Closure
<ol>
 <li>The wound is irrigated with saline and all retractors are removed. The dura is then closed using a running 4-0 Nurolon.</li>
 <li>The remaining steps of closure differ slightly between attending. For JSN, the patch of the pericranium taken at the beginning of the case can be used to assist with water-tight closure of the dura. Multiple tacking holes are placed in the bone and 4-0 Nurolons are passed from the edge of the dura through the tacking holes and secured. Surgicel and Gelfoam are placed on top of the dura, and the bone flap is replaced with KLS screws and plates. Norian bone cement is then used to close off the remainder of the cranial opening in order to prevent later insertion of the muscle onto the dura. The wound is then copiously irrigated with Bacitracin irrigation and closed in layers with 2-0 Vicryls in multiple layers in the muscle, 3-0 Vicryls in the galea and dermis, and a running 4-0 Monocryl in the skin.</li>
 <li>PEK prefers a slightly different method of closure. Following reapproximation of the dura, a piece of Gelfoam is placed overlying the dural incision. Methyl methacrylate is used to fill in the cranial defect and a small KLS plate used to secure the methylmethacrylate prosthetic to the skull. The skin and muscle is then closed as described above and covered with bacitracin ointment.</li>
</ol>
7. Representative Results
Using a review of CPT codes obtained from the VUMC Billing Department, the medical records of 59 patients who underwent microvascular decompression by one of two functional neurosurgeons (JSN or PEK) at Vanderbilt University Medical Center (VUMC) from the period of time from July 2006 to July 2009 were assessed in a retrospective fashion. Study data were collected and managed using REDCap electronic data capture tools2 (REDCap is a secure, web-based application based at Vanderbilt University designed to support data capture for research studies). A summary of the demographics of this patient population is visible in Table 1.
Regarding patient demographics (see Table 1), approximately 66% of patients were female. 10% had a history of multiple sclerosis and 19% had a history of previous surgical procedures for TGN (Table 2). Regarding operative results (see Table 3), 93% of patients experienced significant improvement or full resolution of the facial pain at follow-up ranging from 6 weeks to 2 years. Our method of follow-up consisted of a retrospective review of the electronic medical record. 64% of patients reported themselves as pain-free at their most recent clinic visit following the procedure.
Approximately 15% of patients in the series suffered a CSF leak; 6 (10%) of these patients required ventriculoperitoneal shunt insertion (VPSI). Of note, the rate of CSF leak was appreciably higher in the patient population prior to the routine use of bone flap or methylmethacrylate (MM) buttressing of closure. Specifically, 25% of patients who were closed without a bone flap or methylmethacrylate prosthetic flap developed a CSF leak. In contrast, only 8% of patients closed after bone or MM flap placement had evidence of post-operative CSF leakage. In addition to the results described above, Two (3%) of patients suffered a wound infection. There were no instances of cerebellar damage. Two (3%) of patients reported some degree of post-operative hearing loss.
<table border="1">
 <tbody>
 <tr>
 <td colspan="2">Patient Demographics</td>
 </tr>
 <tr>
 <td>Gender (Male/Female)</td>
 <td>20/39</td>
 </tr>
 <tr>
 <td>History of Multiple Sclerosis (Yes/No)</td>
 <td>6/53</td>
 </tr>
 <tr>
 <td>History of previous surgical procedures for TGN (Yes/No)</td>
 <td>11/48</td>
 </tr>
 </tbody>
</table>
Table 1. Summary of patient demographics.
<table border="1">
 <tbody>
 <tr>
 <td colspan="3">Previous Procedures (11/59)</td>
 </tr>
 <tr>
 <td>Type</td>
 <td>Number</td>
 <td>Results: Pain free (PF) vs. Significantly improved (SI) vs. No improvement (NI)</td>
 </tr>
 <tr>
 <td>Gamma knife</td>
 <td>5 (8%)</td>
 <td>3 PF, 2 SI</td>
 </tr>
 <tr>
 <td>MVD</td>
 <td>2 (3%)</td>
 <td>2 PF</td>
 </tr>
 <tr>
 <td>RFL</td>
 <td>1 (2%)</td>
 <td>PF</td>
 </tr>
 <tr>
 <td>Multiple procedures</td>
 <td>2 (3%)</td>
 <td>PF, SI</td>
 </tr>
 </tbody>
</table>
Table 2. Surgical outcomes of patients who underwent previous procedures prior to undergoing microvascular decompression (MVD) in the current series. Patients are stratified by the specific prior procedure. RFL = radiofrequency lesioning.
<table border="1">
 <tbody>
 <tr>
 <td colspan="2">Surgical Outcome and Complications</td>
 </tr>
 <tr>
 <td>Average length of follow-up</td>
 <td>4 months</td>
 </tr>
 <tr>
 <td>Pain significantly improved or resolved entirely</td>
 <td>55 (93%)</td>
 </tr>
 <tr>
 <td>CSF leak</td>
 <td>9 (15%)</td>
 </tr>
 <tr>
 <td>Aseptic meningitis</td>
 <td>8 (14%)</td>
 </tr>
 <tr>
 <td>Wound infection</td>
 <td>2 (3%)</td>
 </tr>
 <tr>
 <td>Cerebellar damage</td>
 <td>0 (0%)</td>
 </tr>
 <tr>
 <td>Hearing loss</td>
 <td>2 (3%)</td>
 </tr>
 </tbody>
</table>
Table 3. Summary of surgical outcome and complications.
<img alt="Figure 1" src="/files/ftp_upload/2590/2590fig1.jpg" /> 
Figure 1. Operative results: rate of post-operative CSF leakage found to be heavily influenced by whether or not closure was buttressed with bone flap replacement or placement of methylmethacrylate (MM) flap. As a result, bone/MM flap replacement of craniectomy defect is now standard protocol for closure of these procedures.
<img alt="Figure 2" src="/files/ftp_upload/2590/2590fig2.jpg" /> 
Figure 2. Stratification of results describing post-operative improvement in pain.

<ol>
	<li>McLaughlin, M. R., Jannetta, P. J., Clyde, B. L., Subach, B. R., Comey, C. H., Resnick, D. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microvascular+decompression+of+cranial+nerves:+lessons+learned+after+4400+operations.">Microvascular decompression of cranial nerves: lessons learned after 4400 operations.</a> J Neurosurg. 90, 1-8 (1999).</li><li>Harris, P. A., Taylor, R., Thielke, R., Payne, J., Gonzalez, N., Conde, J. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Research+electronic+data+capture+(REDCap):+A+metadata-driven+methodology+and+workflow+process+for+providing+translational+research+informatics+support.">Research electronic data capture (REDCap): A metadata-driven methodology and workflow process for providing translational research informatics support.</a> J Biomed Inform. 42, 377-381 (2009).</li><li>Diener, H. C., Gendolla, A., Katsarava, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Diagnosis+and+treatment+of+head+and+facial+pain.">Diagnosis and treatment of head and facial pain.</a> Internist (Berl). 49, 1343-1348 (2008).</li><li>Love, S., Coakham, H. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Trigeminal+neuralgia:+Pathology+and+pathogenesis.">Trigeminal neuralgia: Pathology and pathogenesis.</a> Brain. 124, 2347-2360 (2001).</li><li>Jannetta, P. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Arterial+compression+of+the+trigeminal+nerve+at+the+pons+in+patients+with+trigeminal+neuralgia.">Arterial compression of the trigeminal nerve at the pons in patients with trigeminal neuralgia.</a> J. Neurosurg. 26, 159-162 (1967).</li><li>Barker, F. G., Jannetta, P. J., Bissonette, P. A. C., Larkins, M. V., Jho, H. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+long-term+outcome+of+microvascular+decompression+for+trigeminal+neuralgia.">The long-term outcome of microvascular decompression for trigeminal neuralgia.</a> N.E.J.M. 334, 1077-1083 (1996).</li><li>Kabatas, S., Albayrak, S. B., Cansever, T., Hepgul, K. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microvascular+decompression+as+a+surgical+management+for+trigeminal+neuralgia:+A+critical+review+of+the+literature.">Microvascular decompression as a surgical management for trigeminal neuralgia: A critical review of the literature.</a> Neurol India. 57, 124-138 (2009).</li><li>Shin, J. C., Kim, Y. C., Park, C. I., Chung, U. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intraoperative+monitoring+of+microvascular+decompression+in+hemifacial+spasm.">Intraoperative monitoring of microvascular decompression in hemifacial spasm.</a> Yonsei MJ. 37, 209-213 (1996).</li><li>Hitotsumatsu, T., Matsushima, T., Inoue, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microvascular+decompression+for+treatment+of+trigeminal+neuralgia,+hemifacial+spasm,+and+glossopharyngeal+neuralgia:+Three+surgical+approach+variations.">Microvascular decompression for treatment of trigeminal neuralgia, hemifacial spasm, and glossopharyngeal neuralgia: Three surgical approach variations.</a> Neurosurg. 53, 1436-1443 (2003).</li><li>Sandell, T., Eide, P. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+microvascular+decompression+in+trigeminal+neuralgia+patients+with+or+without+constant+pain.">Effect of microvascular decompression in trigeminal neuralgia patients with or without constant pain.</a> Neurosurg. 63, 93-99 (2008).</li><li>Miller, J. P., Magill, S. T., Feridun, A., Burchiel, K. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Predictors+of+long-term+success+after+microvascular+decompression+for+trigeminal+neuralgia.">Predictors of long-term success after microvascular decompression for trigeminal neuralgia.</a> J Neurosurg. 110, 620-626 (2009).</li><li>Kalkanis, S. N., Eskandar, E. N., Carter, B. S., Barker, F. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microvascular+decompression+surgery+in+the+United+States.">Microvascular decompression surgery in the United States.</a> Neurosurg. 52, 1251-1261 (1996).</li><li>Park, J. S., Kong, D. S., Lee, J. A., Park, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intraoperative+management+to+prevent+cerebrospinal+fluid+leakage+after+microvascular+decompression+surgery.">Intraoperative management to prevent cerebrospinal fluid leakage after microvascular decompression surgery.</a> Neurosurg Rev. 30, 139-142 (2007).</li></ol>

Dr. Peter Konrad and Dr. Joseph Neimat receive consulting fees and grant support from Medtronic, Inc. There is no associated conflict of interests with the data reported.

Trigeminal neuralgia is a disorder associated with intense episodes of lancinating pain in the distribution of the trigeminal nerve. The severity of this pain can result in significant patient anxiety, malnutrition and even depression3. While possible proximal etiologies of this condition are diverse and include neoplasm or demyelination, 80-90% of cases are related to compression of the trigeminal nerve by an adjacent vessel4,5. In many cases of trigeminal neuralgia, pharmacological treatment is sufficient for adequate control of symptoms. However, the majority of patients require more definitive surgical measures6. Both microvascular decompression (MVD) and ablative procedures (e.g., radiosurgery, percutaneous radiofrequency lesioning, balloon compression, or glycerol rhizolysis) have been shown to be effective at controlling trigeminal neuralgia symptoms acutely&#x2014;however, MVD has been demonstrated to be superior in preventing long-term recurrence7.
Since the first reported uses of MVD by Janetta in the 1960s, adaptations to the procedure have improved patient outcomes. The use of intraoperative auditory brainstem evoked potentials, in particular, has lessened surgical morbidity by monitoring for early irritation of the brainstem and cranial nerves and assisting in prevention of damage to these structures8. Recent reports estimate positive outcome rates of MVD for trigeminal neuralgia in the ranges of 77-94%9,10,11. Nevertheless, significant postoperative complications, namely CSF leak, cerebellar damage and hearing loss9,10, still occur with the procedure. Additionally, recurrence of symptoms has been reported to occur in as many as 39% of patients10,11 following this procedure. In addition to being correlated with intraoperative variables such as nerve location, blood vessel, type and duration of symptoms6,7, the rate of recurrence also has been correlated with experience of the surgeon and hospital in performing MVD12. With proper technique, patient outcome can be maximized and adverse outcomes can be reduced.
This study examined the effectiveness of the surgical technique of MVD performed by two neurosurgeons at Vanderbilt University. The positive outcome rate we measured (93%) is at the high range of those generally reported in the literature9,10. While average duration of follow-up in this series is small, patients are routinely not seen in clinic following the 6-week visit if they remain pain-free and asymptomatic. Given that 64% of patients reported themselves to be entirely pain-free following the procedure, it is not surprising that the average duration of follow-up in this study is short. Present complication rates at our institution are comparable to those reported by others. Initially, MVDs were performed with a suboccipital craniectomy without replacement of the bone flap. After an internal review of the data, which demonstrated an elevated CSF leak of 25%, the protocol was changed to include buttressing with either a methylmethacrylate flap or replacement of the bone flap prior to wound closure. Since this time, our CSF leak rate has approximated 8%&#x2014;consistent with other rates (2.4 &#x2013; 12%) reported in the literature7,13. The percentage of our patients reporting hearing loss (3%) also approximates figures reported in the literature (0.8-2.8%)1,2,12,13, . In no instance did we have a patient with evidence cerebellar damage. 
Our experience suggests that monitoring with BAERs and bone flap replacement are worthwhile options in microvascular decompression. The salient surgical principles and technical nuances utilized at Vanderbilt University have been presented in video format. Furthermore, this video journal format uniquely presents the vascular pathology that many physicians do not routinely see outside the operating room. The results presented suggest that microvascular decompression can be a highly effective procedure performed with low patient morbidity.

<ul>
	<li>Mayfield pins</li>
	<li>Beanbag</li>
	<li>Microscope</li>
	<li>Drill with "matchstick" and/or "craniotome" attachments</li>
	<li>Greenberg retractor</li>
	<li>Cranial microdissectors</li>
	<li>Teflon</li>
</ul>

microvascular decompression: salient surgical principles and technical nuances

Trigeminal neuralgia is a disorder associated with severe episodes of lancinating pain in the distribution of the trigeminal nerve. Previous reports indicate that 80-90% of cases are related to compression of the trigeminal nerve by an adjacent vessel. The majority of patients with trigeminal neuralgia eventually require surgical management in order to achieve remission of symptoms. Surgical options for management include ablative procedures (e.g., radiosurgery, percutaneous radiofrequency lesioning, balloon compression, glycerol rhizolysis, etc.) and microvascular decompression. Ablative procedures fail to address the root cause of the disorder and are less effective at preventing recurrence of symptoms over the long term than microvascular decompression. However, microvascular decompression is inherently more invasive than ablative procedures and is associated with increased surgical risks. Previous studies have demonstrated a correlation between surgeon experience and patient outcome in microvascular decompression. In this series of 59 patients operated on by two neurosurgeons (JSN and PEK) since 2006, 93% of patients demonstrated substantial improvement in their trigeminal neuralgia following the procedure&#x2014;with follow-up ranging from 6 weeks to 2 years. Moreover, 41 of 66 patients (approximately 64%) have been entirely pain-free following the operation.
In this publication, video format is utilized to review the microsurgical pathology of this disorder. Steps of the operative procedure are reviewed and salient principles and technical nuances useful in minimizing complications and maximizing efficacy are discussed.

Watch this Scientific Journal Video about Microvascular Decompression: Salient Surgical Principles and Technical Nuances at JoVE.com

Microvascular Decompression: Salient Surgical Principles and Technical Nuances

There are many available options for management of the patient with trigeminal neuralgia. Microvascular decompression, while the most invasive of all options, is also the most effective at achieving long term remission of symptoms. Video instruction on how to maximize efficacy and minimize complications with this procedure is described.

Trigeminal neuralgia is a disorder associated with severe episodes of lancinating pain in the distribution of the trigeminal nerve. Previous reports ...

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Multispectral Real-time Fluorescence Imaging for Intraoperative Detection of the Sentinel Lymph Node in Gynecologic Oncology

The prognosis in virtually all solid tumors depends on the presence or absence of lymph node metastases.1-3 Surgical treatment most often combines radical excision of the tumor with a full lymphadenectomy in the drainage area of the tumor. However, removal of lymph nodes is associated with increased morbidity due to infection, wound breakdown and lymphedema.4,5 As an alternative, the sentinel lymph node procedure (SLN) was developed several decades ago to detect the first draining lymph node from the tumor.6 In case of lymphogenic dissemination, the SLN is the first lymph node that is affected (Figure 1). Hence, if the SLN does not contain metastases, downstream lymph nodes will also be free from tumor metastases and need not to be removed. The SLN procedure is part of the treatment for many tumor types, like breast cancer and melanoma, but also for cancer of the vulva and cervix.7 The current standard methodology for SLN-detection is by peritumoral injection of radiocolloid one day prior to surgery, and a colored dye intraoperatively. Disadvantages of the procedure in cervical and vulvar cancer are multiple injections in the genital area, leading to increased psychological distress for the patient, and the use of radioactive colloid.
Multispectral fluorescence imaging is an emerging imaging modality that can be applied intraoperatively without the need for injection of radiocolloid. For intraoperative fluorescence imaging, two components are needed: a fluorescent agent and a quantitative optical system for intraoperative imaging. As a fluorophore we have used indocyanine green (ICG). ICG has been used for many decades to assess cardiac function, cerebral perfusion and liver perfusion.8 It is an inert drug with a safe pharmaco-biological profile. When excited at around 750 nm, it emits light in the near-infrared spectrum around 800 nm. A custom-made multispectral fluorescence imaging camera system was used.9.
The aim of this video article is to demonstrate the detection of the SLN using intraoperative fluorescence imaging in patients with cervical and vulvar cancer. Fluorescence imaging is used in conjunction with the standard procedure, consisting of radiocolloid and a blue dye. In the future, intraoperative fluorescence imaging might replace the current method and is also easily transferable to other indications like breast cancer and melanoma.

Fluorescence imaging is a promising innovative modality for image-guided surgery in surgical oncology. In this video we describe the technical procedure for detection of the sentinel lymph node using fluorescence imaging as showcased in gynecologic oncologicy. A multispectral fluorescence camera system, together with the fluorescent agent indocyanine green, is applied.

The prognosis in virtually all solid tumors depends on the presence or absence of lymph node metastases.1-3 Surgical treatment most often combines radical ...

Non-invasive Assessment of Microvascular and Endothelial Function

The authors have utilized capillaroscopy and forearm blood flow techniques to investigate the role of microvascular dysfunction in pathogenesis of cardiovascular disease. Capillaroscopy is a non-invasive, relatively inexpensive methodology for directly visualizing the microcirculation. Percent capillary recruitment is assessed by dividing the increase in capillary density induced by postocclusive reactive hyperemia (postocclusive reactive hyperemia capillary density minus baseline capillary density), by the maximal capillary density (observed during passive venous occlusion). Percent perfused capillaries represents the proportion of all capillaries present that are perfused (functionally active), and is calculated by dividing postocclusive reactive hyperemia capillary density by the maximal capillary density. Both percent capillary recruitment and percent perfused capillaries reflect the number of functional capillaries. The forearm blood flow (FBF) technique provides accepted non-invasive measures of endothelial function: The ratio FBFmax/FBFbase is computed as an estimate of vasodilation, by dividing the mean of the four FBFmax values by the mean of the four FBFbase values. Forearm vascular resistance at maximal vasodilation (FVRmax) is calculated as the mean arterial pressure (MAP) divided by FBFmax. Both the capillaroscopy and forearm techniques are readily acceptable to patients and can be learned quickly.
The microvascular and endothelial function measures obtained using the methodologies described in this paper may have future utility in clinical patient cardiovascular risk-reduction strategies. As we have published reports demonstrating that microvascular and endothelial dysfunction are found in initial stages of hypertension including prehypertension, microvascular and endothelial function measures may eventually aid in early identification, risk-stratification and prevention of end-stage vascular pathology, with its potentially fatal consequences.

Capillaroscopy is a non-invasive, relatively inexpensive methodology for directly visualizing the microcirculation. The forearm blood flow technique provides accepted non-invasive measures of endothelial function.

The authors have utilized capillaroscopy and forearm blood flow techniques to investigate the role of microvascular dysfunction in pathogenesis of ...

Technical Aspects of the Mouse Aortocaval Fistula

Technical aspects of creating an arteriovenous fistula in the mouse are discussed. Under general anesthesia, an abdominal incision is made, and the aorta and inferior vena cava (IVC) are exposed. The proximal infrarenal aorta and the distal aorta are dissected for clamp placement and needle puncture, respectively. Special attention is paid to avoid dissection between the aorta and the IVC. After clamping the aorta, a 25 G needle is used to puncture both walls of the aorta into the IVC. The surrounding connective tissue is used for hemostatic compression. Successful creation of the AVF will show pulsatile arterial blood flow in the IVC. Further confirmation of successful AVF can be achieved by post-operative Doppler ultrasound.

The goal is to produce an arteriovenous fistula that is simple and reproducible. This method does not use sutures or glue adhesive. Therefore the samples can be used with the least amount of foreign materials for analysis.

Technical aspects of creating an arteriovenous fistula in the mouse are discussed. Under general anesthesia, an abdominal incision is made, and the aorta ...

Intravital Microscopy of Tumor-associated Vasculature Using Advanced Dorsal Skinfold Window Chambers on Transgenic Fluorescent Mice

Tumor and tumor vessel development, as well as tumor response to therapeutics, are highly dynamic biological processes. Histology provides static information and is often not sufficient for a correct interpretation. Intravital evaluation, in which a process is followed in time, provides extra and often unexpected information. With the creation of transgenic animals expressing cell-specific markers and live cell tracers, improvements to imaging equipment, and the development of several imaging chambers, intravital microscopy has become an important tool to better understand biological processes. This paper describes an experimental design for the investigation of tumor vessel development and of therapeutic effects in a spatial and temporal manner. Using this setup, the stage of vessel development, tip cell and lumen formation, blood flow, extravasation, an established vascular bed, and vascular destruction can be visualized and followed. Furthermore, therapeutic effects, intratumoral fate, and the localization of chemotherapeutic compounds can also be followed.

This protocol describes the intravital imaging of transgenic mice expressing cell-specific fluorescent markers. Intravital imaging provides a non-invasive method for high-resolution observations in living animals using implantable windows through which the microscopic visualization of processes is possible. This method is especially useful to study longitudinal processes.

Tumor and tumor vessel development, as well as tumor response to therapeutics, are highly dynamic biological processes. Histology provides static ...

Surgical Angiogenesis in Porcine Tibial Allotransplantation: A New Large Animal Bone Vascularized Composite Allotransplantation Model

Segmental bone loss resulting from trauma, infection malignancy and congenital anomaly remains a major reconstructive challenge. Current therapeutic options have significant risk of failure and substantial morbidity.
Use of bone vascularized composite allotransplantation (VCA) would offer both a close match of resected bone size and shape and the healing and remodeling potential of living bone. At present, life-long drug immunosuppression (IS) is required. Organ toxicity, opportunistic infection and neoplasm risks are of concern to treat such non-lethal indications.
We have previously demonstrated that bone and joint VCA viability may be maintained in rats and rabbits without the need of long-term-immunosuppression by implantation of recipient derived vessels within the VCA. It generates an autogenous, neoangiogenic circulation with measurable flow and active bone remodeling, requiring only 2 weeks of IS. As small animals differ from man substantially in anatomy, bone physiology and immunology, we have developed a porcine bone VCA model to evaluate this technique before clinical application is undertaken. Miniature swine are currently widely used for allotransplantation research, given their immunologic, anatomic, physiologic and size similarities to man. Here, we describe a new porcine orthotopic tibial bone VCA model to test the role of autogenous surgical angiogenesis to maintain VCA viability.
The model reconstructs segmental tibial bone defects using size- and shape-matched allogeneic tibial bone segments, transplanted across a major swine leukocyte antigen (SLA) mismatch in Yucatan miniature swine. Nutrient vessel repair and implantation of recipient derived autogenous vessels into the medullary canal of allogeneic tibial bone segments is performed in combination with simultaneous short-term IS. This permits a neoangiogenic autogenous circulation to develop from the implanted tissue, maintaining flow through the allogeneic nutrient vessels for a short time. Once established, the new autogenous circulation maintains bone viability following cessation of drug therapy and subsequent nutrient vessel thrombosis.

Currently any kind of vascularized composite allotransplantation depends on long-term-immunosuppression, difficult to support for non-life-critical indications. We present a new porcine tibial VCA model that can be used to study bone VCA and demonstrate the use of surgical angiogenesis to maintain bone viability without the need of long-term immune-modulation.

Segmental bone loss resulting from trauma, infection malignancy and congenital anomaly remains a major reconstructive challenge. Current therapeutic ...

Using In Vitro Live-cell Imaging to Explore Chemotherapeutics Delivered by Lipid-based Nanoparticles

Conventional imaging techniques can provide detailed information about cellular processes. However, this information is based on static images in an otherwise dynamic system, and successive phases are easily overlooked or misinterpreted. Live-cell imaging and time-lapse microscopy, in which living cells can be followed for hours or even days in a more or less continuous fashion, are therefore very informative. The protocol described here allows for the investigation of the fate of chemotherapeutic nanoparticles after the delivery of doxorubicin (dox) in living cells. Dox is an intercalating agent that must be released from its nanocarrier to become biologically active. In spite of its clinical registration for more than two decades, its uptake, breakdown, and drug release are still not fully understood. This article explores the hypothesis that lipid-based nanoparticles are taken up by the tumor cells and are slowly degraded. Released dox is then translocated to the nucleus. To prevent fixation artifacts, live-cell imaging and time-lapse microscopy, described in this experimental procedure, can be applied.

Using In Vitro Live-cell Imaging to Explore Chemotherapeutics Delivered by Lipid-based Nanoparticles

Live-cell imaging is a powerful tool to visualize dynamic processes. The examination of fixed cells provides only static pictures, which can lead to misinterpretation and confusion about the process. This work presents a method to study uptake, drug release, and intracellular localization of liposomal nanoparticles in living cells.

Conventional imaging techniques can provide detailed information about cellular processes. However, this information is based on static images in an ...

Assessment of Human Adipose Tissue Microvascular Function Using Videomicroscopy

While obesity is closely linked to the development of metabolic and cardiovascular disease, little is known about mechanisms that govern these processes. It is hypothesized that pro-atherogenic mediators released from fat tissues particularly in association with central/visceral adiposity may promote pathogenic vascular changes locally and systemically, and the notion that cardiovascular disease may be the consequence of adipose tissue dysfunction continues to evolve. Here, we describe a unique method of videomicroscopy that involves analysis of vasodilator and vasoconstrictor responses of intact small human arterioles removed from the adipose depot of living human subjects. Videomicroscopy is used to examine functional properties of isolated microvessels in response to pharmacological or physiological stimuli using a pressured system that mimics in vivo conditions. The technique is a useful approach to gain understanding of the pathophysiology and molecular mechanisms that contribute to vascular dysfunction locally within the adipose tissue milieu. Moreover, abnormalities in the adipose tissue microvasculature have also been linked with systemic diseases. We applied this technique to examine depot-specific vascular responses in obese subjects. We assessed endothelium-dependent vasodilation to both increased flow and acetylcholine in adipose arterioles (50 - 350 &#181;m internal diameter, 2 - 3 mm in length) isolated from two different adipose depots during bariatric surgery from the same individual. We demonstrated that arterioles from visceral fat exhibit impaired endothelium-dependent vasodilation compared to vessels isolated from the subcutaneous depot. The findings suggest that the visceral microenvironment is associated with vascular endothelial dysfunction which may be relevant to clinical observation linking increased visceral adiposity to systemic disease mechanisms. The videomicroscopy technique can be used to examine vascular phenotypes from different fat depots as well as compare findings across individuals with different degrees of obesity and metabolic dysfunction. The method can also be used to examine vascular responses longitudinally in response to clinical interventions.

Videomicroscopy systems are used to examine functional properties of isolated adipose tissue arterioles in response to physiological and pharmacological stimuli. This technique can be used to examine microvascular phenotypes in different adipose tissue domains in obese humans.

While obesity is closely linked to the development of metabolic and cardiovascular disease, little is known about mechanisms that govern these processes. ...

Technical Detail for Robot Assisted Pancreaticoduodenectomy

Since its first report in 2003, robotic pancreaticoduodenectomy (RPD) has gained popularity among pancreatic surgeons. Inherent advantages of the robotic platform, including three-dimensional vision, wristed instruments, and improved ergonomics, allow the surgeon to recapitulate the principles of open pancreatoduodenectomy allowing safe oncologic dissection, hemostasis, and meticulous reconstruction. Over the course of the past decade, significant strides have been achieved in outlining the safety, feasibility, and learning curve of the robotic Whipple. When performed by high volume pancreatic surgeons experienced in RPD, recent comparative effectiveness studies show potential advantages compared to the open technique, including reductions in hospital stay and morbidity. National data also show reductions in conversion rates compared to its laparoscopic counterpart. Although long-term oncologic data are still needed, short-term oncologic surrogates of margin resection and lymph node harvest suggest no compromise in oncologic outcomes. As pancreatic surgeons increasingly integrate robotics into their practice, proficiency-based training and credentialing will be necessary for the safe application and dissemination of RPD. Here, we provide the detailed steps of a robotic pancreaticoduodenectomy performed at the University of Pittsburgh Medical Center.&#160;

The following manuscript details a stepwise approach to the robot-assisted pancreaticoduodenectomy performed at the University of Pittsburgh Medical Center.

Since its first report in 2003, robotic pancreaticoduodenectomy (RPD) has gained popularity among pancreatic surgeons. Inherent advantages of the robotic ...

Augmented Reality Navigation-Guided Core Decompression for Osteonecrosis of Femoral Head

Osteonecrosis of the femoral head (ONFH) is a common joint disease in young and middle-aged patients, which seriously burdens their lives and work. For early-stage ONFH, core decompression surgery is a classical and effective hip preservation therapy. In traditional procedures of core decompression with Kirschner wire, there are still many problems such as X-ray exposure, repeated puncture verification, and damage to normal bone tissue. The blindness of the puncture process and the inability to provide real-time visualization are crucial reasons for these problems.
To optimize this procedure, our team developed an intraoperative navigation system on the basis of augmented reality (AR) technology. This surgical system can intuitively display the anatomy of the surgical areas and render preoperative images and virtual needles to intraoperative video in real-time. With the guide of the navigation system, surgeons can accurately insert Kirschner wires into the targeted lesion area and minimize the collateral damage. We conducted 10 cases of core decompression surgery with this system. The efficiency of positioning and fluoroscopy is greatly improved compared to the traditional procedures, and the accuracy of puncture is also guaranteed.

Augmented reality technology was applied to core decompression for osteonecrosis of the femoral head to realize real-time visualization of this surgical procedure. This method can effectively improve the safety and precision of core decompression.

Osteonecrosis of the femoral head (ONFH) is a common joint disease in young and middle-aged patients, which seriously burdens their lives and work. For ...

Real-Time Telemetric Impedance Measurements During Cochlear Implantation

Performing Repeated Intraoperative Impedance Telemetry Measurements during Cochlear Implantation

Impedance measurements are routinely performed during cochlear implantation (CI) after finalized electrode insertion. They may allow conclusions on the electrode's and implant's function. In the postoperative setting, the analysis of impedance changes enables the identification of scarring or inflammation processes around the electrode. Recent studies report associations between impedance telemetry and the site of stimulation. Consequently, repeated impedance measurements during cochlear implant electrode insertion may enable objective feedback on whether the electrode is positioned inside the perilymph or outside the inner ear. With the presented novel method, impedances can be measured in real-time during cochlear implantation. This protocol systematically explains how to perform repeated impedance recordings during CI surgery. These repeated measurements are challenging since they depend on multiple intraoperative methodological factors starting with the draping of the patient. Thus, for successful recordings, a standardized procedure is mandatory. In this article, we comprehensively illustrate the system setup and procedure of performing intraoperative measurements during CI surgery.

Author Spotlight: Advancements in Impedance Monitoring for Cochlear Implant Surgery

Here we present a protocol to conduct repeated impedance telemetry measurements during cochlear implantation (CI). They may allow conclusions on the electrode's and implant's function. Repeated impedance measurements enable objective feedback on whether the electrode is positioned inside the perilymph or outside the inner ear.

Impedance measurements are routinely performed during cochlear implantation (CI) after finalized electrode insertion. They may allow conclusions on the ...