Cervical Spine Approaches by Metrix
The technical possibilities in reaching the cervical spine by videoendoscopy through the anterior and posterior approach are shown.
Between January 1998 and January of 2001, 61 patients were operated on: 32 patients underwent cervical foraminotomy by posterior videoendoscopy and, in 29 patients, discectomy and anterior fusion of the cervical spine was performed.
The approach in each case was chosen based on the patient's clinical conditions:
Foraminotomy was performed when there existed unilateral radiculopathy and the diagnosis was confirmed by image exams. The anterior approach was reserved for cases where there was bilateral radiculopathy or myelopathy. The follow-up in 70% of cases was approximately 24 months.
KEY WORDS: spinal endoscopy, cervical spine, surgical technique.
Endoscopic surgery has been obtaining great success when applied to many medical specialties. These good results have increased the possibilities to reach all segments of the spinal column during spinal surgery.
The endoscopic approach to some areas of the spine became more feasible after Kelly's invention of muscle fiber progressive dilators which created a tubular shaped path through the muscle fibers. Therefore, the microendoscopic approach to the cervical spine, the most mobile and delicate segment of the spinal column, became a reality.
The aim of endoscopic surgery is to perform conventional surgeries in such a way that a minimum of invasiveness to the organs structure is required.
MATERIALS AND METHODS
From January 1998 to January 2001, 61 videoendoscopic surgeries were performed in the cervical spine: 32 foraminotomies and 29 anterior microendoscopic discectomies.
CERVICAL FORAMINOTOMY (POSTERIOR APPROACH)
patient is placed in the semi-sitting position. A skin incision
of 1.8cm is made 1.5cm laterally from the midline. Under radioscopy,
the progressive dilators are inserted through the paravertebral
muscles up to the cervical laminae. After the tubular retractor
is inserted, the optic fiber and camera are adjusted. The triangular
lateral recess must be seen between the two laminae and the facet.
By drilling, a small portion of the facet is removed in order
free a 1cm space inside the radicular foramen. The semi-sitting
position prevents the excess of venous epidural bleeding. The
surgery lasts for about 45 minutes and the patient is discharged
from the hospital the same day. Cervical collar use is not required.
DISCECTOMY AND ANTERIOR MICROENDOSCOPIC FUSION OF CERVICAL SPINE (ANTERIOR APPROACH)
patient is placed in the dorsal decubitus with support under
both shoulders. The disc to be removed is localized by radioscopy.
A small horizontal incision (1.8cm) is made, extending from
the edge of the sternomatoid muscle to the midline. The platisma
and the superficial fascia are opened (ILL -2). By finger dissection
the carotid artery is laterally displaced until the disc is reached.
The esophagus is then medially displaced. The dilators are introduced
and the endoscope is placed over the disc which will have its
fibrous ring incised. To remove the disc, small rongers and a
high-speed drill are required. The disc retractor is put into
place and the posterior spurs and the remaining disc fragments
Finally, under radioscopy, two titanium cages filled with cancellous bone withdrawn from the iliac crest are inserted into the disc space. The cages are 7-8 mm in diameter and have a conic shape in order to maintain the cervical lordosis. The procedure lasts for about 2 hours and the patient is discharged the same day. Cervical collar use is not required.
We present our initial results regarding the videoendoscopic approach of the cervical spine, both posterior and anterior.
APPROACH (VIDEOSCOPIC FORAMINOTOMY) ILL - 3
We found the posterior approach to be a very simple safe and fast procedure. With the aid of the Metrix System (6) we were able to introduce the endoscope through the paravertebral muscles of the cervical spine without need of cutting the muscles or disattaching them from the bone. Placing the patient in the semi-sitting position can reduce epidural bleeding which may be a technical problem.
The disc itself was quite difficult to remove due to epidural bleeding and the necessity to mobilize the dural sac. Therefore such a procedure is limited to root decompression.
Foley and Adamson also reported having good results with the cervical endoscopic foraminotomy. Our patients are discharged 6 hours after the procedure, which generally lasts for 45 minutes, and the cervical collar is not required.
In around 80% of the cases, the patients returned to work within 7 days and in 70% of cases, a significant reduction in analgesics and anti-inflammatory drug administration could be observed. There were no remarkable surgical complications. Two of our patients did not demonstrate clinical improvement so we decided to perform the anterior microendoscopic discectomy 3 and 6 months after the foraminotomy. We achieved good results in both cases.
Adamson (1) does not refer any technical problem or re-operation within 3 months follow up in 24 patients that underwent the procedure. The patient's discharge from hospital in the same day is not mentioned as a cause of complication as well. The author also refers that the technique permits the removal of some fragments of the extruded disc.
Fessler and Foley (3,7) only describe the technique as easy to be performed.
APPROACH (MICROENDOSCOPIC DISCECTOMY) ILL - 4
This technique is more complex than the previous one and is best indicated for medial decompression. The anterior approach requires radioscopy more frequently. Our first concern is the introduction of the endoscope between the carotid artery and the esophagus. In order to make this surgical step safer, we prefer to open the superficial fascia first and then dissect and separate the carotid artery from the esophagus by inserting one finger until the spinal column can be felt. The endoscope is then introduced.
Since the removal of the posterior osteophytes of the disc space is a delicate procedure, special endoscopic refractors and a high speed drill are used.
In 7 of our cases, the placement of two titanium cages was not feasible so only one cage was introduced into the space. In two patients we approached two discs simultaneously without any complication.
Within 15 to 30 days, 85% of our patients were free of strong analgesics and anti-inflammatory drugs. We think that until the bone fusion is completed, final results cannot be evaluated. As this follow-up period has not been completed in all of our cases, we are not able to make a complete analysis and therefore decline to comment as yet. All patients but one who, for personal problems, remained in the hospital for two days, were discharged the same day. Within 30 days, 75% of our patients were back to work.
The videoendoscopic approach to the cervical spine was carried out in 61 cases. Both procedures reduce the extension of tissue lesion and post operative pain.
The patients required a relatively short recuperation period before returning to work. A remarkable reduction in strong analgesics and anti-inflammatory drug administration was observed The posterior approach (foraminotomy) indicated for lateral compressions has the advantage of preserving the disc and does not need grafts at all. However, the failure rate is around 8.3%. The endoscopic anterior approach was feasible as well as the introduction of titanium cages filled with cancellous bone. Only one cage was introduced in 41% of the cases. The skin incision was always smaller than 2cm. We did not have any significant complications. We believe a longer follow-up period is necessary in order to make a more precise conclusion.
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