Indocyanine Green as a Marker for Tissue Ischemia in Spinal Tumor Resections and Extended Revisions: A Technical Note

Background/Objectives: The increasing complexity of spinal oncology procedures, particularly in en-bloc tumor resections, creates challenges in tissue perfusion assessment due to extended operative times and extensive surgical dissection. Real-time visualization of tissue perfusion can be achieved with ICG using commercially available handheld imaging systems, offering potential advantages in spinal oncology cases. This study assessed the utility of ICG in analyzing soft-tissue viability during complex spine procedures extending beyond 7.5 h, with a particular focus on oncologic resections. Methods: Three cases that required over 7.5 h of operative time were chosen for ICG utilization. These cases included an en-bloc malignant peripheral nerve sheath tumor resection, an en-bloc resection of a malignant epithelioid neoplasm, and a long-segment fusion revision for pseudoarthrosis. At the conclusion of the critical portion of the procedure, a handheld intraoperative fluorescence camera was utilized to visualize the tissue penetration of intravenous ICG. Results: Prior to injecting ICG, devascularized tissue was not clearly visible. Injecting ICG allowed clear separation of vascularized (fluorescing) and devascularized (non-fluorescing) tissues. One region of non-florescent tissue was later confirmed to be devascularized with MRI and experienced postoperative infection. Conclusions: As the complexity of spinal oncology procedures increases, ICG fluorescence imaging offers a novel method for real-time assessment of tissue perfusion. This technique may be particularly valuable in extensive tumor resections, post-radiation cases, and revision surgeries where tissue viability is at risk. Further investigation in the spinal oncology population could help establish whether early identification of poorly perfused tissues impacts wound healing outcomes.

Intraoperative indocyanine green (ICG) videoangiography in spinal hemangioblastoma surgery - helpful tool or unnecessary?

BACKGROUND

Hemangioblastomas are highly vascularized tumors that may be associated with extensive architecture of the surrounding pathological vessels. The distinction between feeding arteries and draining veins is usually not obvious during microsurgical en-bloc tumor resection. The aim of this investigation is to provide recommendations in which hemangioblastomas intraoperative indocyanine green (ICG) videoangiography might be beneficial for safe en-bloc tumor resection.

METHODS

This is a single-center retrospective review of resected spinal hemangioblastomas over a 59-month period to identify operations in which ICG videoangiography was used. We analyzed whether intraoperative ICG videoangiography is useful for identifying possible feeding arteries and draining veins. The identified benefits and shortcomings of this technique were summarized.

RESULTS

In total, 39 patients had surgery for removal of spinal hemangioblastomas. Intraoperative ICG videoangiography was performed in 26 surgeries for resection of spinal hemangioblastomas (66.7 %). In 25 of 27 removed hemangioblastomas (92.6 %), intraoperative ICG videoangiography yielded useful insights about the vascularization of the tumor and as thus regarded as helpful. In two cases, the pathological vessels could not be clearly assigned to feeding arteries or draining vessels. Complete tumor removal was achieved in all patients.

CONCLUSION

ICG videoangiography offers real-time intraoperative visualization of the tumor vasculature and can therefore improve surgical decision-making. Ideally, direct microscopic visualization of the structures to be assessed should be aimed for in ICG videoangiography. The information gained from ICG videoangiography may be limited in the case of tumors or vessels that lie deeper or are covered by the myelon or other structures.

Utility of intraoperative fluorescence imaging with indocyanine green for diagnosing spinal schwannoma: A case report

Background

The delayed-window indocyanine green (DWICG) technique is useful for the removal of brain and spinal tumors.

Case Description

A 41-year-old female presented with lower left back and radicular pain. An magnetic resonance imaging (MRI) revealed an extramedullary L3 lesion located ventrally in the spinal canal that appeared to be a schwannoma. Intravenous indocyanine green (dose, 0.25 mg/kg) was administered 1 h before the L2-L4 laminectomy and L3/L4 posterior lumbar fusion. At surgery utilizing a strong near-infrared (NIR) signal, the tumor was clearly visualized through the dura. Complete tumor excision was confirmed when the NIR signal could no longer be detected. Pathologically, the lesion proved to be a schwannoma. A postoperative MRI scan further confirmed complete tumor excision.

Conclusion

In a 41-year-old female, the DWICG technique intraoperatively facilitated localization of a L3 schwannoma through the dura and expedited gross total tumor removal.

A comparative study of analytical models of diffuse reflectance in homogeneous biological tissues: Gelatin-based phantoms and Monte Carlo experiments

Information about tissue oxygen saturation (StO2) and other related important physiological parameters can be extracted from diffuse reflectance spectra measured through non-contact imaging. Three analytical optical reflectance models for homogeneous, semi-infinite, tissue have been proposed (Modified Beer-Lambert, Jacques 1999, Yudovsky 2009) but these have not been directly compared for tissue parameter extraction purposes. We compare these analytical models using Monte Carlo (MC) simulated diffuse reflectance spectra and controlled gelatin-based phantoms with measured diffuse reflectance spectra and known ground truth composition parameters. The Yudovsky model performed best against MC simulations and measured spectra of tissue phantoms in terms of goodness of fit and parameter extraction accuracy followed closely by Jacques' model. In this study, Yudovsky's model appeared most robust; however, our results demonstrated that both Yudovsky and Jacques models are suitable for modeling tissue that can be approximated as a single, homogeneous, semi-infinite slab.

Carbon Dots: From Synthesis to Unraveling the Fluorescence Mechanism

Carbon dots (CDs) being a new type of carbon-based nanomaterial have attracted intensive interest from researchers owing to their excellent biophysical properties. CDs are a class of fluorescent carbon nanomaterials that have emerged as a promising alternative to traditional quantum dots and organic dyes in applications including bioimaging, sensing, and optoelectronics. CDs possess unique optical properties, such as tunable emission, facile synthesis, and low toxicity, making them attractive for many applications in biology, medicine, and environmental areas. The synthesis of CDs is achievable by a variety of methods, including bottom-up and top-down approaches, involving the use of different carbon sources and surface functionalization strategies. However, understanding the fluorescence mechanism of CDs remains a challenge. Various mechanistic models have been proposed to explain their origin of luminescence. This review summarizes the recent developments in the synthesis and functionalization of CDs and provides an overview of the current understanding of the fluorescence mechanism.

The Wonder Dye: Uses and Implications of Indigocyanine Green in Various Surgeries

Indigocyanine green (ICG) is a fluorophore dye that has been extensively used in recent modern times for bioimaging in numerous surgeries to aid in easier identification of occult and often tricky-to-find anatomical structures. Surgery becomes complex and challenging due to multiple anatomical anomalies, pathological fibrosis, obesity, or previous surgeries. To overcome these obstacles in surgery, the surgeon yearns to know the structures present beyond their white light vision so that while dissecting the organ, they can avoid injuring the critical systems in the vicinity of dissection. Near-infrared (NIR) imaging aids in visualising the tissues at depth/in the area of dissection, thereby preventing any possible surgical catastrophes due to them inadvertently damaging surrounding vital structures. Various advantages in surgeries like gastric sleeve surgery, lymph node and tumour detection, localisation of ureters and biliary tracts, and intraoperative tissue perfusion of flaps have been described in this study. This review article aims to compile a short list of utilities of ICG with NIR imaging in various surgical interventions. The merits and demerits of this imaging technique have been noted. The study points out the uses of ICG fluorescence imaging under different surgical fronts. This review article concludes by comparing the results of studies performed by various authors. Results have been compared to conventional surgical modalities.

Intramedullary spinal cavernous malformations with high ossification: a case report and review of the literature

BACKGROUND

Cavernous malformations of the spinal cord are a rare type of vascular malformation, comprising approximately 5 to 16% of all vascular lesions in the spinal cord. Depending on their origin position, these malformations can be distributed in different locations within the spinal canal. Although intramedullary cavernous malformations have been reported in the literature, they are exceedingly rare. Furthermore, highly calcified or ossified intramedullary cavernous spinal malformations are even rarer.

CASE PRESENTATION

Here, we present a case report of a 28-year-old woman diagnosed with a thoracic intramedullary cavernous malformation. The patient had been experiencing progressive numbness in her distal limbs for a period of 2 months. During routine lung computed tomography screening for COVID-19, a hyperdense mass was noted in the patient's spinal canal. Magnetic resonance imaging revealed a mulberry-shaped intramedullary mass at the T1-2 level. The patient underwent surgical treatment, during which the entire lesion was successfully removed, resulting in a gradual improvement of her symptoms. Histological examination confirmed the presence of cavernous malformations with calcification.

CONCLUSIONS

Intramedullary cavernous malformations with calcification are rare and special type that should be treated surgically in the early stage without significant neurological impairment before rebleeding or enlargement of the lesion can occur.

Assessment of Intraoperative Spinal Angiography via the Popliteal Artery for Spinal Vascular Diseases

OBJECTIVE

Intraoperative spinal angiography via the popliteal artery for patients in the prone position has been reported only twice in 4 patients. This study aimed to clarify the safety precautions to be taken with this technique in a larger patient cohort.

METHODS

Seven patients with spinal vascular disorders underwent intraoperative spinal angiography in the prone position via the popliteal artery. Ultrasound was used to evaluate the neurovascular anatomy in the popliteal fossa and guide the arterial puncture. Patient characteristics, features of angiography devices, puncture attempts, and angiography-related complications, such as hematoma formation and injury to the neurovascular bundle, were analyzed.

RESULTS

The average number of arterial puncture attempts was 1.3 times (range: 1-2). Sheaths (4 and 4.5 Fr) with different ineffective lengths were used. In 1 case, a 4.5-Fr sheath was replaced with a 4-Fr sheath with a shorter noneffective length as the length of the catheter limited access to the target. Catheters with Type-JB2 tip shapes were used for craniocervical junction lesions, and those with Type-KAGAWA tip shapes were used for thoracic and lumbar spinal lesions. No puncture site complications were observed in any patient.

CONCLUSIONS

Intraoperative spinal angiography via the popliteal artery was an effective tool in surgeries for spinal vascular diseases. The introduction of the ultrasound enabled atraumatic puncture of the popliteal artery. Spinal targets above T5 to T6 may be inaccessible from the popliteal fossa when using a 100-cm-long catheter.

Preoperative angiographic considerations and neurological outcome after surgical treatment of intradural spinal hemangioblastoma: a multicenter retrospective case series

PURPOSE

Intradural spinal hemangioblastomas are rare highly hypervascularized benign neoplasms. Surgical resection remains the treatment of choice, with a significant risk of postoperative neurological deterioration. Due to the tumor infrequency, scientific evidence is scarce and limited to case reports and small case series.

METHODS

We performed a retrospective multicenter study including five high-volume neurosurgical centers analyzing patients surgically treated for spinal hemangioblastomas between 2006 and 2021. We assessed clinical status, surgical data, preoperative angiograms, and embolization when available. Follow-up records were analyzed, and logistic regression performed to assess possible risk factors for neurological deterioration.

RESULTS

We included 60 patients in Germany and Austria. Preoperative angiography was performed in 30% of the cases; 10% of the patients underwent preoperative embolization. Posterior tumor location and presence of a syrinx favored gross total tumor resection (93.8% vs. 83.3% and 97.1% vs. 84%). Preoperative embolization was not associated with postoperative worsening. The clinical outcome revealed a transient postoperative neurological deterioration in 38.3%, depending on symptom duration and preoperative modified McCormick grading, but patients recovered in most cases until follow-up.

CONCLUSION

Spinal hemangioblastoma patients significantly benefit from early surgical treatment with only transient postoperative deterioration and complete recovery until follow-up. The performance of preoperative angiograms remains subject to center disparities.

Bay Leaf Extract-Based Near-Infrared Fluorescent Probe for Tissue and Cellular Imaging

The development of fluorescence dyes for near-infrared (NIR) fluorescence imaging has been a significant interest for deep tissue imaging. Among many imaging fluoroprobes, indocyanine green (ICG) and its analogues have been used in oncology and other medical applications. However, these imaging agents still experience poor imaging capabilities due to low tumor targetability, photostability, and sensitivity in the biological milieu. Thus, developing a biocompatible NIR imaging dye from natural resources holds the potential of facilitating cancer cell/tissue imaging. Chlorophyll (Chl) has been demonstrated to be a potential candidate for imaging purposes due to its natural NIR absorption qualities and its wide availability in plants and green vegetables. Therefore, it was our aim to assess the fluorescence characteristics of twelve dietary leaves as well as the fluorescence of their Chl extractions. Bay leaf extract, a high-fluorescence agent that showed the highest levels of fluorescence, was further evaluated for its tissue contrast and cellular imaging properties. Overall, this study confirms bay-leaf-associated dye as a NIR fluorescence imaging agent that may have important implications for cellular imaging and image-guided cancer surgery.

Novel Clinical Insights into Spinal Hemangioblastoma in Adults: A Systematic Review

BACKGROUND

Hemangioblastomas (HBs) are well-vascularized, benign central nervous system tumors and the third most common primary spinal cord tumor after astrocytoma/ependymoma, occurring sporadically or as a part of autosomal dominant von Hippel-Lindau disease, in which tumors are often multiple and prone to relapse. Spinal HBs are commonly located in the cervical cord and associated with a syrinx formation. Owing to location and growth trends, they may cause significant neurological deficit, impairing quality of life. We conducted a systematic review to understand better clinical insights into spinal HB in adults and compare spinal HB versus posterior cranial fossa HB.

METHODS

Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines for conducting systematic reviews, we reviewed the English-language literature on adult spinal HB in the MEDLINE/PubMed database over the last 40 years.

RESULTS

We reviewed 237 articles on adult spinal HB and analyzed national and continental distribution, clinical symptoms, tumor location and presence of syringomyelia, treatment strategies and postoperative complications, histology and immunochemistry, and treatment outcomes. We compared individual characteristics in sporadic and von Hippel-Lindau disease spinal HBs. Finally, we compared features of posterior cranial fossa and spinal HBs.

CONCLUSIONS

Spinal cord HBs most commonly have a dorsal intramedullary location. Total surgical tumor resection is the first treatment option; preoperative embolization may be performed to reduce intraoperative bleeding and surgical time. HBs located in the spine have decreased mortality and rate of infection, but increased rates of cardiopulmonary complications compared with HBs in the posterior cranial fossa.

The role of indocyanine green fluorescence in endoscopic endonasal skull base surgery and its imaging correlations

OBJECTIVE

The use of endoscope-integrated indocyanine green (E-ICG) has recently been introduced in skull base surgery. The quantitative correlation between E-ICG and T1-weighted gadolinium-enhanced (T1WGd) images for skull base tumors has not been previously assessed, to the authors' knowledge. In this study, the authors investigated the indications for use and the limitations of E-ICG and sought to correlate the endoscopic fluorescence pattern with MRI contrast enhancement.

METHODS

Following IRB approval, 20 patients undergoing endoscopic endonasal skull base surgery between June 2017 and August 2018 were enrolled in the study. Tumor fluorescence was measured using a blue color value and blood fluorescence as a control. Signal intensities (SIs) of tumor T1WGd images were measured and the internal carotid artery (ICA) SI was used as a control. For pituitary adenoma, the pituitary gland fluorescence was also measured. The relationships between ICG fluorescence and MRI enhancement measurements were analyzed.

RESULTS

Data showed that in pituitary adenoma there was a strong correlation between the ratios of gland/blood fluorescence to gland/ICA SI (n = 8; r = 0.92; p = 0.001) and tumor/blood fluorescence to tumor/ICA SI (n = 9; r = 0.82; p = 0.006). In other pathologies there was a strong correlation between the ratios of tumor/blood fluorescence and tumor/ICA SI (n = 9; r = 0.74; p = 0.022). The ICG fluorescence allowed perfusion assessment of the pituitary gland as well as of the nasoseptal flaps. Visualization of the surrounding vasculature was also feasible.

CONCLUSIONS

Defining the indications and understanding the limitations are critical for the effective use of E-ICG. Tumor fluorescence seems to correlate with preoperative MRI contrast enhancement.

Surgical Treatment of Intramedullary Hemangioblastomas: Current State of Problem (Review)

Intramedullary hemangioblastomas (HAB) refer to very rare highly vascularized vascular spinal cord tumors associated with various neurological disorders. Effective HAB therapy to a greater extent depends on diagnostic accuracy and the absence of intra- and postoperative complications.

The present study is a review of publications concerned with modern diagnostic and therapeutic techniques to control spinal HAB. The authors showed that perfusion computed tomography, computed tomographic angiography, and magnetic resonance angiography can be reasonably used for diagnosis and differentiation in a number of HAB due to their high vascularization. Preoperative embolization significantly reducing intraoperative bleeding risks is highly efficient. Some authors recommend this procedure in case of large lesions and high risks of intraoperative bleeding. The review also considered intraoperative imaging of a tumor and its feeding vessels using indocyanine green providing inspectability over the total tumor resection and clear imaging of tumor vascular architecture. The advantages and restrictions of the mentioned procedures were described.

Use of Intraoperative Indocyanine Green Angiography for Feeder Vessel Ligation and En Bloc Resection of Intramedullary Hemangioblastoma

BACKGROUND

As vascular tumors, intramedullary hemangioblastomas are associated with significant intraoperative blood loss, making them particularly challenging clinical entities. The use of intraoperative indocyanine green or other fluorescent dyes has previously been described to avoid breaching the tumor capsule, but improved surgical outcomes may result from identifying and ligating the feeder arteries and arterialized draining veins.

OBJECTIVE

To describe the use of combined preoperative angiography and intraoperative indocyanine green use for the identification of feeder arteries and arterialized draining veins to decrease blood loss in the resection of intramedullary hemangioblastomas.

METHODS

A patient with cervical myelopathy secondary to a large C3 hemangioblastoma and cervicothoracic syrinx underwent a C2-3 laminoplasty with resection of the lesion. To reduce intraoperative blood loss and facilitate safe lesion resection, the vascular architecture of the lesion was defined via preoperative digital subtraction angiography and intraoperative use of indocyanine green. The latter permitted ligation of the major and minor feeding arteries and arterialized veins prior to tumor breach, allowing for facile en bloc resection of the lesion.

RESULTS

The lesion was resected en bloc with minimal blood loss (approximately 100 mL) and without intraoperative neuromonitoring signal changes. The patient remained at neurological baseline throughout their stay.

CONCLUSION

We present a written and media illustration of a technique for intraoperative indocyanine green use in the en bloc resection of intramedullary hemangioblastoma.

Quantitative Analysis of Near-Infrared Indocyanine Green Videoangiography for Predicting Functional Outcomes After Spinal Intramedullary Ependymoma Resection

BACKGROUND

One of the most critical steps in surgery for spinal intramedullary ependymomas is the resection of small feeding arteries from the anterior spinal artery with anatomical preservation of the normal circulation of the ventral spinal cord.

OBJECTIVE

To quantitatively analyze the microcirculation of the ventral spinal cord by near-infrared indocyanine green videoangiography (ICG-VA) after the spinal intramedullary ependymoma resection.

METHODS

This retrospective study included 12 patients (7 male and 5 female; average age 55.2 years, range 36-79 years). Patients' neurological conditions were assessed based on the modified McCormick functional schema of grade 1 (neurologically normal) to 5 (severe deficit). Postoperative functional assessment was conducted at least 3 months after surgery. Quantitative analysis of vascular flow dynamics was carried out following spinal intramedullary ependymoma resection. Fluorescence intensities were measured and the indocyanine green (ICG) intensity-time curves were analyzed and compared with the functional outcomes after surgery.

RESULTS

Microscopically total or subtotal resection of the intramedullary ependymoma was achieved in all cases. Average peak time on ICG-VA was significantly shorter in the postoperative functional grade 1 to 2 group than in the postoperative functional grade 3 to 5 group, but there was no significant difference in average peak intensity between the 2 groups. Postoperative functional grade and the peak time of ICG, but not peak intensity, appeared correlated.

CONCLUSION

To the best of our knowledge, this is the first report showing that quantitative analysis of ICG-VA may predict functional outcomes after spinal intramedullary ependymoma resection.

Health-Related Quality of Life After Microscopic Total Removal of Spinal Intramedullary Ependymomas in a Single-Institute 3-Year Prospective Study

OBJECTIVE

Health-related quality of life (HRQOL) after surgery for spinal intramedullary benign encapsulated tumors remains unclear. A single-institute, 3-year, prospective study was conducted to examine HRQOL after microscopic total removal of spinal intramedullary ependymomas using a safe and precise strategy.

METHODS

A cohort of 20 patients with a possible diagnosis of spinal intramedullary benign ependymomas was recruited. Patients who underwent microscopic total removal of the tumor and for whom the pathologic diagnosis was verified as World Health Organization grade II benign ependymoma were included. Sixteen patients (average age, 48.7 years) were eligible for study analysis. Careful assessment was performed for all patients before and 6-12 months after surgery. The 36-Item Short Form Health Survey was used to assess HRQOL, with the surveyor recording answers as reported by the individual patient.

RESULTS

Average total HRQOL score was 431.1 before surgery and was maintained at 434.2 at 6-12 months postoperatively. Patients with mild functional symptoms tended to demonstrate a higher total HRQOL score preoperatively compared with patients with moderate to severe functional symptoms. A strong correlation was noted between postoperative functional conditions and preservation of HRQOL.

CONCLUSIONS

This is the first study focusing on HRQOL after microscopic total removal of spinal intramedullary ependymomas. This study suggested that radical surgery using a safe and precise strategy appears justifiable and that preservation of neurologic function after surgery may lead to maintenance of postoperative HRQOL.

The role of indocyanine green videoangiography with FLOW 800 analysis for the surgical management of central nervous system tumors: an update

OBJECTIVE

Indocyanine green videoangiography (ICG-VA) is an intraoperative technique used to highlight vessels in neurovascular surgery. Its application in the study of the vascular pathophysiology in CNS tumors and its role in their surgical management are still rather limited. A recent innovation of ICG-VA (i.e., the FLOW 800 algorithm integrated in the surgical microscope) allows a semiquantitative evaluation of cerebral blood flow. The aim of this study was to evaluate for the first time the systematic application of ICG-VA and FLOW 800 analysis during surgical removal of CNS tumors.

METHODS

Between May 2011 and December 2017, all cases in which ICG-VA and FLOW 800 analysis were used at least one time before, during, or after the tumor resection, and in which surgical videos were available, were retrospectively reviewed. Results of the histological analysis were analyzed together with the intraoperative ICG-VA with FLOW 800 in order to investigate the tumor-related videoangiographic features.

RESULTS

Seventy-one patients who underwent surgery for cerebral and spinal tumors were intraoperatively analyzed using ICG-VA with FLOW 800, either before or after tumor resection, for a total of 93 videoangiographic studies. The histological diagnosis was meningioma in 25 cases, glioma in 14, metastasis in 7, pineal region tumor in 5, hemangioblastoma in 4, chordoma in 3, and other histological types in 13 cases. The authors identified 4 possible applications of ICG-VA and FLOW 800 in CNS tumor surgery: extradural surveys allowed exploration of sinus patency and the course of veins before dural opening; preresection surveys helped in identifying pathological vascularization (arteriovenous fistulas and neo-angiogenesis) and regional venous outflow, and in performing temporary venous clipping tests, when necessary; postresection surveys were conducted to evaluate arterial and venous patency and parenchymal perfusion after tumor removal; and a premyelotomy survey was conducted in intramedullary tumors to highlight the posterior median sulcus.

CONCLUSIONS

The authors found ICG-VA with FLOW 800 to be a useful method to monitor blood flow in the exposed vessels and parenchyma during microsurgical removal of CNS tumors in selected cases. In particular, a preresection survey provides useful information about pathophysiological changes of brain vasculature related to the tumor and aids in the individuation of helpful landmarks for the surgical approach, and the postresection survey helps to prevent potential complications associated with the resection (such as local hypoperfusion or venous infarction).

Surgical Outcomes of Posterolateral Sulcus Approach for Spinal Intramedullary Tumors: Tumor Resection and Functional Preservation

BACKGROUND

Selection of the access myelotomy is a key issue in surgery for spinal intramedullary tumors. This study focused on surgical outcomes with the posterolateral sulcus (PLS) approach, equivalent to dorsal root entry zone myelotomy.

METHODS

This retrospective study of the 10-year period from 2007 to 2016 included 90 cases of spinal intramedullary lesions (99 operations). A PLS approach was indicated for intramedullary lesions situated laterally in the spinal cord showing no contact with the spinal cord surface. Neurological conditions before and after surgery were carefully assessed objectively.

RESULTS

A PLS approach was applied in 34 of the 99 operations (34.3%). Among 70 cases involving astrocytic tumor, ependymal tumor, cavernous malformation or hemangioblastoma, 23 cases (32.9%) were operated on using a PLS approach. Microscopically gross total or subtotal removal of the tumor was achieved in 18 of 23 cases (78.3%). These 18 cases demonstrated mild deterioration of motor function on the approach side early after surgery, but usually resolving within several months postoperatively. Average grade of the modified McCormick functional schema before surgery was maintained 6 months postoperatively. Average grade of the sensory pain scale before surgery was significantly improved by 6 months postoperatively. Segmental dysesthesia on the approach side unexpectedly remained in 2 of 18 cases (11.1%) even late after surgery.

CONCLUSIONS

These findings suggest that the PLS approach can provide direct access to tumors with minimal tissue damage, when applied appropriately after careful case selection.