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Ohara et al. Percutaneous endoscopic lumbar laminectomy

patient, single-level decompression is only performed interlaminar space and a thick ligamentum flavum,
if it is likely to affect the patient’s symptoms; if the the obturator cannot be inserted into the interlaminar
patient requests treatment of all the vertebral levels space. Therefore, obturator and sheath should be
potentially causing the symptoms, microscopic surgery inserted until they reach the bone surface. However, if
is performed instead. This procedure is used to treat the obturator is not inserted deeply along the surface
all types of central canal stenosis and lateral canal of the bone, the soft tissues will be more difficult to
stenosis. deal with after endoscope insertion. In this institution,
a bevel-type sheath at a 30° angle is typically used.
Surgical instruments
A special single-port endoscope is used for PELL, as After the soft tissues have been dealt with, drilling
with PED. In this institution, a scope 7 mm or 8 mm is initiated at the center of the superior edge of the
in diameter is used (VERTEBRIS, Winnova Richard lamina under the lesion [Figure 1]. Epidural fat tissue
Wolf Medical Instruments Corporation, Germany). The may persist at this site even in patients with severe
7-mm endoscope has an 8-mm sheath and is easily LCS, meaning that the depth of the epidural space
manipulated, even in a narrow interlaminar space, can be safely confirmed. After confirming the epidural
but is incompatible with some of the instruments space, drilling is performed as far as the attachment
that can be used for an 8-mm endoscope. An 8-mm of the ligamentum flavum on the approach side of the
endoscope can be used with drill sizes up to 3.5 mm, lamina under the lesion, to enable the dissection of the
which is useful for drilling large areas of bone. The ligament at its attachment.
8-mm endoscope also enables the use of a larger
Kerison punch, as well as curved and curved basket The superior facet process is then also drilled, and
punches (Winnova Richard Wolf Medical Instruments the stenosis of the lateral recess on the same side is
Corporation, Germany). The 8-mm endoscope is easier treated in this step. If the ligamentum flavum cannot
to use at first, until proficiency in the procedure has be detached from its attachment, its complete removal
been achieved. A special drill (Primade 2; Nakanishi, is difficult. As only limited kinds of instruments can
Japan), and a bipolar flexible radiofrequency probe be used, flavectomy cannot be performed unless
(Elman Trigger-Flex probe; Elman International) are either the attachment of the ligamentum flavum at the
also used. lamina is dissected using a drill, or laminotomy itself
is carried out as far as the attachment of the ligament,
Surgical procedure as in a conventional lumbar surgery. Debulking of the
As PELL requires a longer operation time compared ligamentum flavum can carried out using a punch
or basket punch. Therefore, the bone shape and
with PED, PELL is currently performed under general the lesion responsible for the symptoms should be
anesthesia. In most cases, the approach is performed established using preoperative images.
on the side with the most prominent symptoms, but the
opposite side may be chosen if preoperative images The use of a single-port endoscope makes it difficult
indicate that decompression of the osseous stenosis is to perform a flavectomy on both sides, particularly a
likely to be easier. If the operator is right-handed and superolateral flavectomy on the contralateral side. If
no laterality of the symptoms is present, an approach
from the left is used as it allows the surgeon to control the insertion angle of the endoscope is limited, making
the endoscope to drill the lower edge of the upper manipulation on the opposite lateral side problematic,
lamina easily. Discography is not performed if only the base of the spinous process of the superior
the posterior component should be decompressed, lamina must first be drilled to secure the pathway for
but if disc manipulation may be required, discography insertion. If widespread laminotomy of the ipsilateral
is undertaken from the opposite side. After set-up of lamina above the lesion is required, drilling is easier
the equipment, a frontal fluoroscopic image is used if a straight-type sheath is initially used, as this helps
to check the extent of decompression during the to prevent soft tissue from entering the sheath. Once
procedure. Physiological saline is used for irrigation, a sufficient interlaminar space has been obtained,
which is delivered at low pressure through instillation switching to a 30° bevel or duck-bill type sheath for
from a height of 30-40 cm above the operating table. subsequent operations is necessary to treat the
opposite side, as these cannot be carried out using a
A 7-mm skin incision is made just beside the spinous straight-type sheath. When changing the sheath, an
process under the affected level. An obturator is obturator is inserted as a guide.
advanced from this location along the base of the
spinous process above the lamina below, as far as Postoperative management
the interlaminar space. In patients with a narrow Hemostasis of bleeding from soft tissue and resected
Mini-invasive Surgery ¦ Volume 1 ¦ June 30, 2017 75