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Keywords:

  • Microsurgery;
  • acoustic neuroma;
  • skull base surgery;
  • vestibular schwannoma

Abstract

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. MATERIALS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. BIBLIOGRAPHY

Introduction:

Since the early 1960s, microsurgical removal has been the standard for curative treatment of vestibular schwannomas and neurotologic skull base lesions. The narrow operative corridor with only one surgeon actively operating sometimes interferes with simultaneous application of standard surgical principles such as suction, counter tension, and dissection and makes attempts at “co-surgery” into “sequential” surgery. Surgical efficiency is often delayed by the need to change surgical instruments and reorient the surgical field.

Methods:

In this four-handed technique, the microscope is arranged with binocular microscope heads and the surgeons facing each other at the head of the patient and operating simultaneously.

Results:

Since 2006, the authors have operated 97 lesions using the four-handed technique. The distinct visualization advantage of the 180° binocular arrangement over use of a side arm is that both surgeons have the same stereoscopic perspective. Specific ergonomic advantages were identified for rapid debulking in large tumors, simultaneous neurologic mapping for sharp facial nerve dissection, counter traction for tumor dissection, neurologic tissue retraction/protection for safe bipolar cautery, and real-time intraoperative consultation/collaboration.

Conclusions:

Specific technical and microscope arrangements are necessary to utilize the four-handed technique; however, distinct advantages in tissue handling and surgical efficiency are facilitated.


INTRODUCTION

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. MATERIALS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. BIBLIOGRAPHY

Since the early 1960s, microsurgical removal has been the standard for curative treatment of vestibular schwannomas (acoustic neuromas) and other skull-base lesions.1 Despite its advantages, microsurgery has limitations. The narrow operative corridor with only one surgeon actively operating sometimes interferes with simultaneous application of standard microsurgical techniques such as suction, counter tension, retraction, dissection, and neurologic mapping, thus interfering with efficient surgery as the operating surgeon has to change instruments and visualization. Although side-arm optics have improved from the early monocular visualization tubes,2 post-beam splitter visualization through a camera or a side arm inherently limits active assistance during microsurgery due to the lack of three-dimensional stereoscopic vision and the awkward access to the surgical field by the co-surgeon.

MATERIALS AND METHODS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. MATERIALS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. BIBLIOGRAPHY

The key operative arrangement for this approach is orienting the microscope with binocular eyepieces 180° between the two co-surgeons without the need for a beam splitter. Thus, the co-surgeons both have stereoscopic visualization and are operating opposite each other, both facing the operative field and able to control instruments in the operative field. During the time of this study, the surgeons used either the Zeis OPM-1 Pantero (Carl Zeis AG, Surgical Products Dvision, Oberkochen, Germany) or the Leica OHS-1 microscopes (Leica Microsystems, Wetzlar, Germany). The patient positions are selected depending on the surgical approach (translabyrinthine, retrosigmoid, middle fossa, or combined), and both co-surgeons can be sitting or standing (Figs. 1 and 2). Although standard microsurgical instrumentation is utilized, the authors routinely have two suction arrangements available as both co-surgeons often simultaneously employ suction as a retraction/aspiration tool (Figs. 3 and 4).

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Figure 1. Both surgeons are standing during two-surgeon, four-handed middle fossa encephalocele surgery. The binocular eyepieces are arranged at 180° so that a beam splitter is not required.

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Figure 2. Both surgeons are seated during translabyrinthine two-surgeon, four-handed microsurgery. A single scrub nurse can pass instruments.

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Figure 3. Close-up view of hand positions during four-hand, two-surgeon translabyrinthine acoustic neuroma removal.

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Figure 4. Microscope view of four instruments in the surgical field during translabyrinthine acoustic neuroma microsurgery. Note each surgeon holds a fenestrated suction, while one holds the tumor with a cup forceps and the other dissects the facial nerve from the tumor with microscissors.

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RESULTS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. MATERIALS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. BIBLIOGRAPHY

Between December 2006 and July 2010, the authors operated 97 lesions using the four-handed technique: acoustic neuroma (59), meningiomas (8), encephaloceles (19), vestibular neurectomy (8), microvascular decompression (1), chondroma (2). Tumor sizes ranged from 0.5 cm to 5.8 cm with operative times ranging from 2.25 hours to 6 hours.

The authors identified five specific technical advantages with four-handed microsurgery over the traditional two-handed arrangement: real-time intraoperative consultation, counter traction, facilitated debulking in large tumors, coordinated nerve mapping, and facilitated hemostasis.

Real-Time Intraoperative Consultation

By having the co-surgeons truly operating simultaneously, this technique permits real-time intraoperative consultation. For instance, one of the operators can visualize and isolate a structure such as a blood vessel and both co-surgeons can palpate and dissect the structure to decide if it is an expendable tumor vessel or a vital perforating artery traversing adjacent to the tumor. Other examples include deciding whether a structure is an arachnoid band or a nerve rootlet, identifying displaced anatomy in the tumor bed, and even recommending technique alternatives and identifying different planes of dissection during difficult nerve dissection.

Counter Traction

One co-surgeon can place a structure on tension while the other can sharply dissect and use suction simultaneously. For instance, with one surgeon holding the arachnoid band on tension, the other surgeon can sharply dissect with one hand while keeping the surgical plane clean with a suction in the second hand.

Facilitated Debulking in Large Tumors

During intracapsular debulking, devitalized tissue and surgical field aspiration can be accomplished by one surgeon while the other surgeon proceeds in delivering/dissecting additional tissue in a coordinated fashion. This maneuver was accomplished with traditional cup forceps debulking, sharp scissors debulking as well as mechanically assisted debulking with Cavitron ultrasonic surgical aspirator (CUSA) debulking, rotary dissector debulking, or vertical-oscillator debulking (Myriad device).

Although this study did not have distinct time allocation data in each step of the procedure for comparison with previous techniques, the authors noted that debulking in the 11 large tumors (>3.5 cm) was more efficient with the present technique and attribute the approximate 1-hour operative time savings in large tumors to the debulking efficiency. However, formal time analysis and a larger number of cases is necessary to quantify this advantage.

Coordinated Nerve Mapping

One surgeon can use the nerve stimulator to map tissue in proximity to a nerve targeted for preservation while the second surgeon could continue with sharp dissection without having to change instruments or reorient the surgical field.

Facilitated Hemostasis

In situations with brisk bleeding in the microsurgical field, visualization and safe hemostasis can be compromised. The four-handed technique for this situation allows one surgeon to gradually release pressure by a cottonoid pledget or oxidized cellulose with suction and a forceps while the other surgeon uses suction and bipolar cautery to achieve hemostasis.

Limitations

Space

Four hands in a microsurgical field can be crowded and sometimes impossible to employ. The instruments occupy a finite amount of space filled with vulnerable structures easily damaged by errant movements. We did not modify the surgical approaches to permit four instruments into the field; however, microscope positioning and distance were often adjusted to a longer focal length to permit maneuvering under the lens. Ongoing dialogue between the co-surgeons is vital for instrument positioning and safe application of this technique.

Microscope Design

Although the ability to position the eyepieces at 180° allows most operative microscopes to be arranged for four-handed microsurgery, the hand-operated controls are designed for one surgeon operating the controls. Dialogue between the co-surgeons again is necessary for assuring appropriate angulation, magnifications, and focus for both surgeons.

Surgeon Positions

Depending on the surgical approach, four-handed microsurgery can require awkward neck and hand positions for one of the surgeons. Issues such as surgeon height, arm length, and flexibility need to be considered in patient, surgeon, and instrument positions. Although our team has successfully controlled the operative environment so that four-handed surgery has been possible in all of our cases, preoperative planning and clear communication of surgeon needs to the ancillary staff is necessary for appropriate microscope configuration, draping, and scrub nurse preparation.

DISCUSSION

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. MATERIALS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. BIBLIOGRAPHY

Microsurgeons have successfully incorporated basic surgical principles with a two-hand technique despite the limited space. For instance, a suction tube can be used both as a retraction tool and aspirator to permit visualization and counter traction for dissection or hemostasis. Occasionally an assistant can reach over from the side-arm observer position and gently retract a structure. Nonetheless, situations arise in which the surgeon must change instruments to accomplish a maneuver such as stimulation or dissection; during the instrument change the surgical field changes and aspiration of blood or cerebrospinal fluid requires reoreintation and potentially loss of surgical efficiency, which was less troublesome to the authors with the four-handed technique.

The authors do not posit this approach as unique. One of the authors (K.S.) routinely used this technique during neurosurgical residency. Nonetheless, we were unable to identify descriptions of the technique in neurosurgical or neurotologic publications. Because the technique in our hands has offered specific ergonomic and patient safety advantages, systematic consideration seemed beneficial. Like many aspects of collaborative surgery, many of these procedures could be performed by just one surgeon; however, the patient benefit of both specialties offering expertise makes co-surgery particularly valuable for added patient safety and surgical expertise.3 Four-handed approaches are a natural extension of the principles of interspecialty collaboration.

BIBLIOGRAPHY

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. MATERIALS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. BIBLIOGRAPHY
  • 1
    Glasscock M, Steenerson R. History of acoustic neuroma surgery 1961–present. In: House W, Luetje C, eds. Acoustic Tumors, Vol. 1, Diagnosis. Los Angeles, CA: House Ear Institute; 1985: 34.
  • 2
    Uluc K, Kijoth G, Baskaya M. Operating microscopes: past, present, and future. Neurosurg Focus 2009; 27: E4.
  • 3
    Arriaga M. Overview of transtemporal skull base surgery. In: Brackmann DE, Shelton C, Arriaga MA, eds. Otologic Surgery, 3rd ed. Philadelphia, PA: Elsevier; 2010: 519.