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Paraglottic Space in Supracricoid Laryngectomy
Min-Sik Kim, MD;
Dong-Il Sun, MD;
Kyung-Ho Park, MD;
Kwang-Jae Cho, MD;
Young-Hak Park, MD;
Seung-Ho Cho, MD
Arch Otolaryngol Head Neck Surg. 2002;128:304-307.
ABSTRACT
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Background Paraglottic space (PGS) is a connective tissue compartment of the larynx
and is important in the extension of laryngeal cancer. It communicates with
the preepiglottic space superiorly and with the extralaryngeal region inferiorly
through the gap within the cricothyroid membrane. Transglottic cancer of the
larynx, which spreads within PGS, is characterized by a high incidence of
laryngeal skeleton invasion and of cervical metastasis. Determining the correct
stage of transglottic cancer of the larynx is difficult, leading to therapeutic
failure of partial laryngectomy in some cases.
Objective To clinically confirm a pathologically complete resection of PGS from
the piriform sinus mucosa by supracricoid partial laryngectomy in laryngeal
cancers involving PGS.
Materials and Methods Eight patients with transglottic cancer whose cancer was confirmed clinically
and pathologically at stages T2b or higher underwent supracricoid partial
laryngectomy. During supracricoid partial laryngectomy, we performed a sharp
dissection of PGS from the piriform sinus mucosa to obtain a complete resection
margin while preserving the piriform sinus mucosa. Microscopic evaluation
of the specimens was made for the invasion of PGS and the safe margin distance
from the piriform sinus mucosa.
Results Pathological cancer invasion of PGS was confirmed in 7 of 8 patients
and a sufficient pathological margin from tumor invasion to the piriform sinus
mucosa was obtained. The average safety margin was 10.3 mm.
Conclusion Supracricoid partial laryngectomy could be considered a safe surgical
modality for cancers not extending to PGS.
INTRODUCTION
PARAGLOTTIC SPACE (PGS) is a connective tissue compartment of the larynx
and was first described in 1962 by Tucker and Smith.1
They reported that PGS borders the thyroid cartilage anterolaterally, the
conus elasticus interoinferiorly, the ventricle and quadrangular membrane
inferiorly, and the piriform sinus mucosa dorsally. Paraglottic space is also
connected with the preepiglottic space superiorly and with the extralaryngeal
space inferiorly through the gap in the cricothyroid membrane.1-2
Kirchner and Cornog3 described transglottic
cancer as laryngeal cancer invading both sides of the false vocal cord and
true vocal cord across the ventricle, and reported that the extension of laryngeal
cancer is achieved through PGS. Transglottic cancer invading PGS is characteristically
known to show a high incidence of laryngeal skeleton invasion and cervical
metastasis.4-5 Determining the
accurate stage of transglottic cancer is difficult preoperatively,5 leading to failure of partial laryngectomy in some
cases.6-7 Laryngeal cancer invading
PGS was treated in the past with total laryngectomy; however, patients who
undergo this procedure lose their voice, resulting in social and emotional
problems. The development of partial laryngectomy in recent years has led
to the development of surgical methods that preserve the maximal physiological
function of the larynx while totally removing the primary site. Supracricoid
partial laryngectomy (SCPL) is one of the methods reported that can be used
in laryngeal cancer cases needing total laryngectomy by resecting the tumor
with PGS.6-8 However,
pathological verification in this procedure has not been established because
the tumor is removed completely from the piriform sinus where no barrier is
present from laryngeal cancer cases. Thus, we tried to confirm whether a tumor
can be resected safely by separating PGS from the piriform sinus mucosa SCPL
in locally advanced laryngeal cancer cases with preoperative PGS invasion
of stage T2b or higher.
PATIENTS AND METHODS
The study was conducted with 8 patients who were diagnosed as having
transglottic cancer at stage T2b or higher with radiologically suspected invasion
of PGS and decreased or fixed movement of the vocal cords. These patients
underwent SCPL at the Department of Otolaryngology–Head and Neck Surgery,
Kangnam St Mary's Hospital, College of Medicine, and The Catholic University
of Korea, from March to December 1999. All cases were squamous cell carcinoma,
and the primary lesion was glottic cancer in 7 cases (9 sides) and supraglottic
cancer in 1 case. The study included 2 patients with stage T4 cancer where
the vocal cord invasion of both sides was present (Table 1). There were 3 cases of T2b, 3 cases of T3, and 2 cases
of T4 cancer; 6 cases underwent cricohyoidoepiglottopexy; 1, tracheocricohyoidoepiglottopexy;
and 1, cricohyoidopexy. All patients were male with an average age of 63.6
years.
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Paraglottic Space Invasion and Safety Margin From Tumor to Piriform
Sinus Mucosa*
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SURGERY METHODS
Supracricoid partial laryngectomy described by Laccourreye et al8-9 was performed according to tumor location.
After dissecting the superior and nontumor-bearing side of PGS tissue during
surgery according to tumor invasion by the conventional method, the lesion
side of PGS was completely dissected from the piriform sinus mucosa. To expose
the piriform sinus mucosa, an index finger was inserted in the piriform sinus,
pulling it anterolaterally while pulling the other side of the larynx in the
opposite direction. The remaining PGS tissue, not including the piriform sinus
mucosa, was sharply dissected completely and the PGS tissue was removed from
the piriform sinus mucosa with a sharp knife (Figure 1).
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Figure 1. Surgical method of supracricoid
partial laryngectomy. Surgeon's left index finger is placed under the patient's
right piriform sinus mucosa (P) pulling it anterolaterally while pulling the
other side of the larynx in the opposite direction. The remaining paraglottic
space tissue (G) is dissected using a No. 15 cold blade while preserving the
piriform sinus mucosa.
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TISSUE TREATMENT
The resected tissue was fixed in 10% formaldehyde, decalcified in 8%
formic acid for 4 days, and embedded in paraffin. After cutting 4-mm horizontal
sections from the top, middle, and bottom sections of PGS, the supraglottic
paraglottic region, glottic region, and infraglottic region of PGS (by observing
the embedded tissue), the invasion of PGS was determined visually in each
section. When invasion of PGS was present, the distance between the resection
margin of the piriform sinus and tumor mass was measured, and the tissue slides
were prepared from the site nearest the tumor mass and stained with hematoxylin-eosin.
The distance between the tumor mass to the piriform sinus mucosa was then
measured and the average distances of the 3 sites were calculated (Figure 2).
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Figure 2. Planes of section. A, The distance
(safety margin) of the horizontal section of the larynx at the level of glottis
between the tumor and piriform sinus mucosa (arrow). B, Median section of
larynx shows horizontal section of tumor from upper, middle, and lower margins
(3 lines).
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RESULTS
Paraglottic space invasion was confirmed histologically in 7 (9 sides)
of 8 cases (10 sides) of clinically suspected PGS invasion. The safety margin
from the tumor mass to the piriform sinus mucosa in the supraglottis was 3
mm in supraglottic cancer and 9 to 19 mm in glottic cancer. The invasion was
mainly present in supraglottic cancer and the safety margin was maintained
but was too close. Although the invasion was present in the glottic area with
the safety margin of 2 mm in supraglottic cancer and 5 to 17 mm in glottic
cancer, the safety margin was sufficient in most cases. The safety margin
from the middle of the tumor was 15 and 17 mm in 2 of 3 cases with initial
PGS invasion; 5 mm in 1 case with confirmed PGS invasion; and 2 mm, 5 mm,
and 8 mm in 3 cases of T3 tumors. In 2 cases (4 sides) of T4 tumors, the safety
margin was 5 mm in the right side and 6 mm in the left side in 1 case and
14 mm in the right side and 16 mm in the left side in the other case. Among
these, the closest safety margin was 2 mm from the superior glottic region
to the piriform sinus in the T3 transglottic tumor originated from the supraglottis
(Figure 3).
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Figure 3. An approximate 2-mm safety margin
(arrow) was noted between piriform sinus mucosa (M) and the tumor mass (T)
invading paraglottic space (hematoxylin-eosin, original magnification x
40).
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In all 8 cases, PGS could be dissected from the piriform sinus mucosa
with a sufficient surgical margin; the average distance between the tumor
to the piriform sinus mucosa was 10.3 mm. No postoperative aspiration or dysphagia
was present in any of the patients (Table
1).
COMMENT
The concept of compartmentalization of the larynx was introduced by
Pressman et al,10 who detected that the flow
of a dye injected under the supraglottis mucosa stops at the inferior margin
of the false vocal cord. The authors also determined that the ventricle functions
as an anatomical barrier. After the introduction of the compartmentalization
concept of the larynx, Tucker and Smith1 reported
that the PGS is a compartment in the larynx composed of connective tissue;
it borders the thyroid cartilage anterolaterally, the conus elasticus inferomedially,
the ventricle and quadrangular membrane superomedially, and the piriform sinus
dorsally. The PGS connected to the preepiglottic space superiorly, to the
extralaryngeal space through the gap in the cricothyroid membrane inferiorly,
and included the thyroarytenoid muscle.1-2
However, Maguire and Dayal11 defined PGS as
a small space composed of fat tissue bordering the thyroarytenoid muscle medially,
the thyroid cartilage laterally, and the piriform sinus dorsally; the thyroarytenoid
muscle from PGS was excluded. Sato et al12
reported similar results. Thus, defining the exact area of PGS is still debatable.
The inferior PGS located between the medial thyroarytenoid muscle and lateral
thyroarytenoid muscle plays an important role in decreasing the vocal cord
and arytenoid movements as the route of glottic cancer extension.13 In other words, a decrease in the vocal cord movement
represents the invasion of a tumor into the medial or lateral thyroarytenoid
muscle through PGS in supraglottic cancer, and invasion into PGS of a tumor
through the medial thyroarytenoid muscle in glottic cancer. In the present
study, we confirmed that of 8 patients with suspected tumor invasion into
PGS clinically and radiologically, 7 patients experienced tumor invasion into
PGS histologically.
Transglottic cancer is laryngeal cancer invading the false vocal cord
and true vocal cord across the ventricle. The origin of this tumor could be
glottic cancer progressing superiorly, supraglottic cancer extending inferiorly,
or a tumor originating from the ventricle extending into both directions.
Clinical characteristics of this cancer are submucosal extension of the false
vocal cord, PGS invasion, cartilage invasion, and cervical lymph node metastasis
in about 30% to 40% of cases.14 Hao et al15 compared a T3 tumor invading only the true vocal
cord with T3 transglottic cancer and reported that transglottic cancer showed
more cervical lymph node metastasis, with 27% compared with 17% in the T3
tumor; there was more extracapsular spread in transglottic cancer with 43%
compared with 27%.15 Also, Biller and Lawson14 reported that vertical partial laryngectomy could
result in incomplete resection in transglottic cancer and could cause a high
rate of recurrence. Transglottic cancer extends usually through PGS; thus,
total laryngectomy was performed to completely remove PGS when a tumor invaded
the PGS due to a high failure rate with past conventional methods of partial
laryngectomy. However, total laryngectomy results in loss of voice and creates
serious emotional and social problems for the patient. Therefore, it is important
to accurately determine the presence or absence of PGS invasion preoperatively
for the selection of treatment method and operative results.
Zbären et al16 reported that PGS
invasion can be diagnosed accurately in 86% of cases with computed tomography
and in 89% with magnetic resonance imaging. We clinically determined the presence
or absence of PGS invasion using computed tomography when the vocal cord movement
was decreased or fixed. Laccourreye et al8-9
recently reported on SCPL to remove PGS, epiglottis, and preepiglottic space,
including thyroid cartilage. Different from total laryngectomy, this procedure
not only avoids losing the physiological function of voice and a permanent
tracheotomy, but is also most effective in removing PGS as the partial laryngectomy
that could replace the conventional total laryngectomy in cases of transglottic
cancer invading PGS.10, 17-18
In the surgical method of SCPL completely resecting PGS, the most important
aspect is preserving the piriform sinus mucosa that forms the dorsal margin
of PGS and anteromedial margin of the hypopharynx. Moreover, since PGS is
situated closely to the piriform sinus, PGS could be the route of laryngeal
cancer extending to the hypopharynx or hypopharyngeal cancer extending to
the larynx.19 Although Laccourreye et al8-9 reported that PGS could be completely
resected using SCPL, not many studies reported on the surgical procedures
that could resect PGS while safely preserving the piriform sinus (the posterior
border of PGS). Thus, we tried to remove PGS as much as possible from the
piriform sinus mucosa by inserting an index finger into the piriform sinus
mucosa while pulling laterally to easily confirm the piriform sinus mucosa
and pulling the rest of the larynx tissue to the opposite direction so that
the removal of the other tissue was achieved. A surgical knife was used while
confirming the piriform sinus mucosa. As a result, we could remove PGS from
the piriform sinus mucosa in all 8 cases while giving a sufficient surgical
margin. We histologically confirmed that the surgical margin was safe in all
cases, especially in the cases where the surgical margin was more than 5 mm
of localized stage T2b tumors. The average surgical margin was 8.9 mm in tumors
in stages T3 and T4. Caution was needed in 1 case of supraglottic cancer where
the tumor invasion was 2 mm from the surgical margin, possibly because the
distance between the piriform sinus mucosa and PGS in the supraglottis is
anatomically close.20 Thus, SCPL used in the
present study needs to be performed with more caution in transglottic cancer
in dissecting PGS. A relatively safe surgical margin could be obtained in
the rest of the cases. The patients are being followed up in an outpatient
setting, with no sign of recurrence 1 year after surgery; no postoperative
dysphagia or other complications due to the surgery were present.
CONCLUSIONS
Supracricoid partial laryngectomy is a procedure that permits a safe
en bloc dissection of a tumor including PGS when the tumor is confined within
the PGS and could be used more effectively by safely separating PGS from the
piriform sinus mucosa while managing to preserve the piriform sinus mucosa.
This procedure needs to be performed after more prudent evaluation and selection
in patients with transglottic cancer originating from the supraglottis.
AUTHOR INFORMATION
Accepted for publication August 24, 2001.
This study was presented as a poster at the annual meeting of the American
Head and Neck Society, Palm Desert, Calif, May 14-16, 2001.
Corresponding author and reprints: Min-Sik Kim, MD, Department of
Otolaryngology–Head and Neck Surgery, Kangnam St Mary's Hospital, The
Catholic University of Korea, Seoul, Korea 137-040 (e-mail: entkms{at}cmc.cuk.ac.kr).
From the Department of Otolaryngology–Head and Neck Surgery,
College of Medicine, The Catholic University of Korea, Seoul, Korea.
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