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5 Diagnostic Method andInstrumentation inRhinology
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Fig. 5.17 39year old male, with NK Tcell lymphoma of
nasal cavity, underwent
MIP image (a) reveals FDG avid mass involving the nasal
cavity and diffuse uptake in axial and appendicular skeleton. (b) Irregular soft tissue thickening of right nasal cav-
18
F-FDG PET/CT for staging.
Hodgkin lymphoma (NHL). Most common NHL in the head and neck region is
of the Waldeyer ring, in which palatine
tonsil is most common followed by nasopharynx. Primary nasopharyngeal lymphoma constitutes 8% of all head and
neck lymphomas.
18
F-FDG PET/CT is
useful for the detection of the Primary
Nasopharyngeal lymphoma (PNL), its
extent of disease, and response evaluation. Studies have revealed that 18F-FDG
PET/CT is not reliable to differentiate
between PNL and NPC [21]. The nasal
cavities and paranasal sinuses are rarely
affected by primary NHL, these can be
differentiated from squamous carcinomas of these areas on conventional imaging due to their sub-mucosal origin.
18
F-FDG PET/CT also has a role in the
ity and involving the nasal septum and nasopharynx, with
diffuse FDG uptake. (c) FDG avid extension of mass into
infra-orbital region of right eye and right ethmoid seen.
No other lesion noted in rest of the body
metastatic evaluation and disease activity
response assessment (Fig.
5.17).
(iv) Mucosal Melanoma:
Mucosal malignant melanoma is a very
rare tumor counting for approximately
0.8–1.3% of all melanomas. Sinonasal
malignant melanoma (SNMM) accounts
roughly for 4% of all head and neck melanomas and sinonasal malignancies [
22].
In routine practice of head & neck radiological assessment, CT and MRI are used
for initial diagnosis. These modalities
have their limitation in metastatic evaluation and detection of residual/recurrent
disease. 18F-FDG-PET/CT imaging has
higher sensitivity and specicity over
conventional imaging in the staging of
malignant melanoma [23]. Therefore,
18
F-FDG-PET/CT can be a one-stop-
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Fig. 5.18 50 years old female, with known malignant melanoma, underwent
radiotherapy to look for disease status. (a) MIP image showing increased uptake in the region of nasal cavity, lungs, and
18
F-FDG-PET/CT post-surgery and
shop imaging for detection of primary as
well as metastatic diseases (Fig. 5.18).
Studies have shown the use of
18
F-FDGPET/CT in staging, restaging postsurgery, and response assessment of
SNMM [24]. However, non-specic
mucosal FDG uptake inlocal infective or
inammatory conditions may lead to
misinterpretation of PET.
(v) Olfactory Neuroblastoma:
Olfactory neuroblastoma also known as
Esthesioneuroblastoma (ENB) is a rare
neuroectodermal tumor of the nasal cavity, comprising 2% of all sino-nasal neoplasms [25]. Imaging plays an important
role in the diagnosis and staging of olfactory neuroblastoma. CT is essential for
axial skeleton. (b) Axial CT and Pet/CT fused images showing mucosal thickening in lateral wall of left nasal cavity
with FDG uptake, suggestive of residual disease. (c) FDG
avid parenchymal metastatic nodule in right lung lower lobe
evaluation of the osseous involvement of
the cribriform plate, fovea ethmoidalis,
and lamina papyracea. MRI assesses the
soft tissue extent and dural involvement
of the disease. Like other neuroectodermal tumors, ENB shows MIBG (Metaiodo benzyl guanidine), a nor-epinephrine
analog, concentration.
for diagnostic planar and SPECT and
123
I labeled MIBG
131
labeled MIBG for therapeutic indications
are already in use for extra-nasal neuroblastoma. MIBG scintigraphy has been
found to be useful in differentiating
olfactory neuroblastomas from other
nasal tumors [26]. 18F-FDG-PET/CT is
used for staging, restaging, and follow up
of ENB [27]. Some studies have shown
I
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Fig. 5.19 33 years old male, with suspected nasal neuroendocrine carcinoma, post three cycles of docetaxel,
underwent
PET/CT fused images showing sift tissue mass in right
68
Ga DOTANOC PET/CT. (a) Axial CT and
the superior diagnostic role of Cholinebased PET (18F or 11C labeled) over FDG
PET, however, more data is required to
establish this [28]. High expression of
Somatostatin Receptors (SSTR), particularly SSTR-1 and 2, has been documented in tumor cells of neuroblastoma
[29]. Extending from this knowledge
Savelli etal. have reported SSTR scintigraphy and peptide receptor radionuclide
therapy (PRRT) in a case of ENB, they
have reported good uptake of 68Ga
nasal cavity with intense tracer uptake. (b) Sagittal CT
and PET/CT fused images showing mass occupying the
right nasal cavity. Biopsy revealed olfactory
neuroblastoma
DOTANOC in tumor and response to 90Y
DOTATATE (Fig.5.19) [30].
(vi) Occult Primary:
Carcinomas of unknown primary (CUP)
account for 5–10% of head and neck cancers [31]. Oropharynx is one of the most
common sites of origin of head and neck
occult primaries, accounting for nearly
90% of CUPs, the nasopharynx and
hypopharynx are relatively less common
‘hot spots’ for occult primary tumors
[32]. When conventional imaging, i.e.,
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CT and MRI, fail to localize occult primary, PET/CT becomes the next investigation of choice. FDG PET/CT scan has
an overall staging accuracy of 69–78%, a
positive predictive value of 56–83%, a
negative predictive value of 75–86%, a
sensitivity of 63–100%, and a specicity
of 90–94% in CUP [33]. Apart from the
localization of primary, PET also assists
in identifying more feasible sites for
biopsy. However, FDG PET/CT also has
its drawbacks, the presence of infective/
inammatory pathology in nasal cavity
and paranasal sinuses may give rise to
false positives.
(C) Sentinel Lymph Node Scintigraphy
Sentinel lymph node biopsy is based on the
identication of the predictable pattern of
lymphatic drainage to a primary tumor, and
its role as an effective lter for tumor cells
[34]. Histopathological conrmation of the
involvement of sentinel lymph node helps in
limiting unnecessary neck dissections. There
are various techniques for the identication
of the sentinel lymph nodes, commonly used
are the dye method and radiotracer method.
In the radiotracer method, the radiolabeled
colloid suspension is injected at the primary
site, and planar and SPECT/CT images are
acquired at 15, 30, and 60min from injection. SPECT/CT provides anatomical conrmation of lymph node level of the sentinel
lymph node. During surgery, the exact location of the nodes may be conrmed using a
hand-held gamma detector probe. These
identied lymph nodes are then biopsied to
look for the spread of malignancy, and assist
in decisions regarding neck dissection. Few
sentinel lymph node scintigraphy studies
have been done for sino-nasal malignancies,
showing an increment in the identication of
involved nodes of up to 14% [35].
(D) Therapeutic Potential
Tumors expressing somatostatin receptors
(SSTR) like NET of the nose and paranasal
sinuses, may be considered for peptide
receptor radionuclide therapy (PRRT) targeting these receptors, such as
177
Lu (lute-
tium), 90Y (yttrium), or
225
Ac (actinium)
labeled DOTATE.Olfactory neuroblastoma
like other neuroblastomas is amenable to
131
I-MIBG therapy. JNA has been shown to
express both SSTRs and PSMA, therefore,
theoretically can receive PRRT or PSMA
labeled
177
Lu or
225
Ac therapy.
5.4 Part D: Bacteriology
andVirology
5.4.1 Introduction
Antonie Philips van Leeuwenhoek was the rst
scientist who observed bacteria. Bacteria are single cell organism seen by light microscopy which
unlike viruses is able to multiply by binary ssion
as well as survive outside other cells. After birth,
the nasopharynx of a new born does not remain a
sterile site for more than 48h. With rapid acquisition of colonizing bacteria initially from the
maternal genital tract and later followed by organism which are either ingested or received from
carrier skin. The normal indigenous ora consists
of gram-positive and gram-negative, aerobic and
anaerobic bacteria including the oral streptococci,
Bacteroides species, Corynebacterium species,
and Neisseria species.
5.4.1.1 Bacteriology ofNose andPNS
Common cold (Rhinitis) is dened as an inammation of the nasal mucous membrane or lining.
Bacterial agents are responsible for 10–15% of
cases of rhinitis which include Chlamydia pneu-
moniae, Mycoplasma pneumoniae, and Group A
streptococci [36]. Maxillary sinus is the most commonly involved sinus. The subsequent order of
frequency of sinus involvement is the ethmoid,
frontal, and sphenoid sinuses) [37]. Streptococcus
pneumoniae and Haemophilus inuenzae are the
most common etiological agents among
community- acquired cases (50–60%). Moraxella
catarrhalis is responsible for around 20% of cases
in children. Methicillin-resistant Staphylococcus
aureus (MRSA) concern is emerging. Among
anaerobes, Prevotella spp. Fusobacterium spp.,
are found [38]. Among chronic sinusitis, common
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pathogens are S. pneumoniae, H. inuenzae, and
M. catarrhalis. Other pathogens that are less fre-
quently seen are anaerobic streptococci, Prevotella
spp., and Fusobacterium spp. M. catarrhalis is
one of the possible agent in chronic sinusitis in
children [36].
Nosocomial sinusitis is a relatively common
occurring complication, mainly in critical care.
Risk factors are nasal intubation, nasal-enteric
tube. Bacterial species that are prevalent in environment of hospital are the common etiological
agents for nosocomial cases including,
Staphylococcus. aureus, Pseudomonas spp.,
Klebsiella pneumonia, etc. Such infections are
commonly polymicrobial and multidrug resistant. During the last three decades, extrapulmonary tuberculosis (EPTB) has gained
special attention because of the human immunodeciency virus (HIV) pandemic. Mycobacterium
tuberculosis most frequently reaches the lung and
rarely involves paranasal sinuses and nasopharynx. It reaches the nose and facial bones through
blood stream or lymphatics. Antral lavage examination for AFB and culture for Mycobacterium
tuberculosis can facilitate early diagnosis, there
by avoiding surgical intervention.
Steps and Site of Specimen Collection [39]
1. Rhinitis: The sample is collected from ante-
rior nares. If pus is found on anterior rhinos-
copy, dry swab is applied over it to collect
sample. If no pus is found, the swab is moist-
ened rst and then the anterior nares are
swabbed. Swab specimen should be taken
from at least 1cm inside the nares. The trans-
port medium for the swab is mainly for staph-
ylococcal carriers. To culture the lesion, the
sample is to be collected from the advancing
margin of the lesion. For nasopharyngeal
swab, exible swab stick is inserted per nasal,
it is passed through the nasal cavity till it
impinges on the nasopharynx, and then rotate
for 5–10 s. Swab can be moistened with
Stuart’s or Amie’s medium. (This moistening
is only for bacterial etiology suspected). Thin
wire or exible swab is dipped into transport
medium. Transport to laboratory
immediately.
2. Sinusitis is the clinical diagnosis. Maxillary
sinusitis is the most common type of sinusitis, and specimen is collected by aspiration
and subjected to culture and susceptibility
testing [36, 40]. Therapy can be modied
according to the etiological agent and treatment response. As nasal cavity is colonized
heavily with respiratory ora, contamination
of sample collected from paranasal sinuses is
quite common. To help in differentiating true
infection from contamination, quantitative
methods can be helpful. Colony count of at
least 104 colony- forming units per milliliter
(CFUs/mL) of aspirated material is suggestive of infection.
3. General instructions for specimen transport:
The specimen should reach the laboratory as
soon as possible. Ideally specimen must
reach the laboratory within <2h. If specimen
is taken in odd hours, it can be store at 4°C
(This only applies to Virus etiology as mentioned with Coronavirus). For suspected
Bacterial etiology, we can keep the specimen
at room temperature maximum for 24 h. It
should not be refrigerated, Sinus drainage is
unacceptable for smear or culture because of
contamination with naturally occuring ora.
Nasal smear is also useful to evaluate eosino-
phils. It may help in diagnosing the suspected
cases of allergic rhinitis. Even in uncomplicated
cold, polymorpho-nuclear leukocytes predominance in nasal secretions can be seen and does
not always a marker for bacterial superinfection.
Routine microbiological investigations like
bacterial cultures or antigen detection are
required when specic bacterial etiological agent
like group A streptococcus, nasal diphtheria, or
Bordetella pertussis is suspected.
5.4.2 Staining Procedures
• Gram Stain: It divides the bacteria into Grampositive and Gram-negative bacteria.
• Ziehl–Neelsen Technique: It divides the bacteria into acid fast and non-acid fast.
Mycobacterium tuberculosis being acid fast,
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is presumptively diagnosed with this
technique.
• Albert Stain: It is performed for Corynebacterium
diphtheriae, will appear as green bacilli with
purple-blue metachromatic granules and in typical arrangement.
5.4.3 Culture Media Are Required
toIsolate theBacteria
fromtheClinical Specimens
1. Primary Plating Medias are blood agar,
MacConkey agar, chocolate (Heated blood
agar) agar. It is for isolation of aerobic bacteria (Figs.5.20, 5.21, and 5.22).
2. Lowenstein-Jensen (LJ) medium: It is used
for isolation of Mycobacterium tuberculosis.
3. Loefer’s serum slope and Potassium tellurite
agar (PTA): It is used for isolation of
Corynebacterium diphtheriae.
4. Blood agar and Pike’s medium (Blood agar
containing crystal violet and sodium azide):
For Streptococcus spp.
5. Robertson’s cooked meat medium (RCM),
PRAS (pre-reduced anaerobic sterilized)
transport medium, Stuart’s transport medium
for anaerobes.
Growth from the medium can be identied by
conventional biochemical tests, automated identication system, or MALDI-ToF {Matrixassisted laser desorption/ionization (MALDI),
and the mass analyzer is time-of-ight (TOF)
analyzer}.
5.4.3.1 Storage ofMedia
Bacterial cultures are generally stored on agar
plates or in stab cultures in the refrigerator at
4°C.Long-term storage methods should be considered for maximum bacterial viability like:
Fig. 5.20 MacConkey Agar
Fig. 5.21 Blood Agar
1. Freezing samples
2. Freeze-drying (Lyophilization)
5.4.4 Nucleic Acid Amplication
Techniques (NAAT)
It is increase the yield of sample. The various
NAATs used are Polymerase chain reaction
Fig. 5.22 Chocolate Agar
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(PCR), Real-time polymerase chain reaction,
Ligase chain reaction (LCR), Transcriptionmediated amplication (TMA), Nucleic acid
sequence-based amplication (NASBA), and
Strand displacement amplication (SDA) [41].
The PCR technique involves three basic steps
to amplify the number.
1. DNA extraction from the organism
2. Amplication of extracted DNA
3. Gel electrophoresis of the amplied product
5.4.5 Antibiotic Sensitivity,
Resistance, andPrevention
Testing for antibiotic sensitivity is often done by
the Kirby-Bauer method or automated antibiotic
susceptibility system. Small disc containing antibiotics are placed onto a plate upon which bacteria are growing. If the bacteria are sensitive to the
antibiotic, a clear ring, or zone of inhibition, is
seen around the disc indicating poor growth.
Antibiotic resistance occurs when bacteria
change in some way that reduces or eliminates
the effectiveness of drugs, chemicals, or other
agents designed to cure or prevent infections. The
bacteria survive and continue to multiply causing
more harm. Bacteria can do this through several
mechanisms. To preserve the potency of existing
antibiotics, overall antibiotic use must be
decreased. Physicians, pharmacists, and the general public must avoid the careless use of these
valuable drugs. Antibiotics must be prescribed
only for bacterial infections and in the proper
dose for the correct amount of time.
5.4.6 Viruses inENT
Viruses are the smallest unicellular organisms,
are obligate intracellular. Viruses are the most
primitive microorganisms infecting man. Viral
infections are responsible for rhinitis in 20–25%
of cases. In rhino-pathologies of viral origin, the
microscopic picture is characterized by fairly
aspecic cellular changes gathered under the
term “ciliocytophthoria,” which comprises
degenerative alterations of the ciliary ultrastructure (shortening and focal or even general loss of
the cilia), the cytoplasm (contraction of the cytoplasm, or even shortening of the upper portion of
the cell body), the nucleus (chromatin margination with a ground-glass appearance and intranuclear inclusions). The range of viruses that
commonly infects the respiratory tract is notoriously wide (rhinovirus, coronavirus, respiratory
syncytial virus [RSV], adenovirus, parainuenza
virus, coxsackievirus, cytomegalovirus).
However, no specic cytomorphologic alteration
has been found till date that could represent a
turning point in epidemiology, despite viral infections accounting for the bulk of human infectious
diseases, or in prognosis and therapy. Some have
strongly linked with the carcinogenesis of several
tumor types, particularly Burkitt’s lymphoma
and nasopharyngeal carcinoma (NPC) with
Epstein-Barr virus (EBV).
5.4.7 Laboratory Diagnosis ofViral
Diseases
Laboratory Diagnosis of Common Cold [37]:
The culture, antigen detection, PCR, or serologic
methods are the commonly employed diagnostic
methods for viral pathogens that cause the common cold. As such, routine diagnostic methods
neither required nor of any help in cases with
common cold. It is only helpful when therapy
with an antiviral agent is required for specic
etiological agent. As such, viruses have been
infrequently isolated from patients with acute
sinusitis. Timing of sinus aspiration may be
responsible for this. Sinus aspiration is usually
done in persistent sinusitis when case has been
symptomatic for at least 7–10 days [42].
Normally, by this time, viral infection may be
diminishing. Respiratory viruses have been
recovered from approximately 10% of sinus aspirates. Approximately 30–40% of sinus aspirates
in cases with acute sinusitis are not positive for
any bacteria. It is presumed that many of these
infections are, in fact, viral. Nasopharyngeal and
oropharyngeal swab is also collected to evaluate
virus. Swab should be Dacron or polyester
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ocked swab. For transport of samples for viral
detection, Viral transport medium (VTM) containing antifungal and antibiotic supplements to
be used. Avoid repeated freezing and thawing of
specimen. Transport the sample to laboratory at
4°C.If specimen is required to be stored, store at
4°C less than equal to 5days while at -70°C for
>5days.
5.4.7.1 Detection Methods forViruses
Direct Demonstration of Virus is done by electron microscopy, immune-electron microscopy,
Fluorescent microscopy, Light microscopy.
ELISA, direct immunouorescence (IF),
Immunochromatography (ICT) test, ow through
assays are the methods for detection of viral antigens. Hemagglutination Inhibition assay (HAI),
neutralization test, and complement xation test
(CFT) are the conventional techniques for detection of the specic antibodies. Enzyme-linked
immunosorbent assay (ELISA) is a technique
used to detect antibodies to infectious agents in a
sample. Antibodies are made in response to infection and so an antibody ELISA can indicate
whether or not an animal has been in contact with
a certain virus. Molecular methods include
RT-PCR is for RNA and DNA detection. The isolation of virus is done by animal inoculation
method, embryonated egg inoculation method,
and by tissue cultures such as organ culture,
explant culture, cell line culture [43].
5.5 Part E: Advanced
Instruments inRhinology
The normal anatomy of the nose and paranasal
sinuses is highly variable and complicated.
Certain parts were very difcult to access with
existing cold instruments so clearance of disease from these areas was difcult. With the
advent of the concept of functional endoscopic
sinus surgery, preservation of uninvolved
mucosa is very important so outcome of surgery is better. It improves the quality of life to
great extent. With the advancement in instrumentation in the eld of rhinology, the knowledge of normal anatomy and its variation is
improved, handling of diseased and normal
healthy mucosa is improved, access to difcult
area is also improved so the disease clearance
is better than with cold instruments which in
term reduce the chances of recurrence and
residual disease. Sinonasal region is surrounded by vital structures such as brain and
orbit. Inadvertent injury to these vital structures can create devastating complications.
Powered instrument also reduces the rate of
complications and fear to handle disease close
to these vital structures, which in turn reduces
the morbidity, mortality, and nancial burden
on community. Endoscopes, debrider, coblator,
navigation system, ultrasonic aspirator, radiofrequency ablation, etc. are advances in the last
two decades.
1. Endoscopes—It is prepared by using ber
optics and powerful lens systems to provide
lighting and visualization of the relatively
inaccessible areas through conventional instruments. The portion of the endoscope inserted
into the body can be rigid or exible. Hopkins
rod lens system was developed to provide
endoscopes of different length, diameter, and
angle to provide visualization in certain areas.
The rigid endoscopes commonly used are 2.7,
3, and 4mm in diameter. 2.7mm is for pediatric and 4 mm is for adult nasal procedures.
Visualization is better with the increase in
diameter of endoscopes as more light can
transmit to the surgical eld. The working
length of nasal endoscopes is 18 cm. Nasal
endoscopes are available in various degrees
such as 0, 15, 30, 45, 70, and 90° (Fig.
[44]. 0° and 30° endoscopes are the most commonly used endoscopes. With the increase in
degrees, we can see more hidden part of nose
and paranasal sinuses. Seventy degree endoscope is useful for visualization of frontal
sinus and maxillary sinus oor. All the endoscopes are now autoclavable. 0° nasal endoscope comes with green color coding. Fifteen
and thirteen degrees endoscopes comes with
white and red color coding. Color coding for
45°, 70°, 90° endoscopes are blue, yellow, and
black respectively.
5.23)
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Fig. 5.23 Nasal
endoscopes
147
Video endoscopes are mechanically similar to ber-endoscopes. They have charged
couple device (CCD) ‘chip’ and supporting
electronics mounted at the tip, to and fro wiring replacing the optical bundle and further
electronics and switches occupying the site of
the ocular lens on the upper part of the control
head [45]. A CCD chip is an array of 33,000–
100,000 individual photo pixel receiving photons reected back from the mucosal surface
and producing electrons in proportion to the
light received. The advantages are improved
image quality, improved monitor view, removing the necessity to grasp the instrument close
to the surgeon eye has hygienic advantages
and it also improved instrument design and
handling techniques. The only limiting factor
is no direct viewing. Endoscopic observation
can further increase by the light source and
digital camera.
Light Source further augment visualization by increasing light output. With the
advent of the xenon light source (peak wavelengths in the 800–1000nm range), visualization has markedly improved. Xenon
sources have been observed to be 3 times
greater than that of standard halogen sources,
with white rather than yellow-tinted light
quality. In comparison to halogen light,
xenon is more robust and efcient, with
greater life, less heat creation. The drawback
of xenon bulbs is the cost to install and
replace, it takes a few seconds to attain full
glow and give off more glare.
Digital cameras use chips that process
color information. Modern 3-chip cameras
have spate chips to process each of the three
primary colors, red, blue, and green. This
markedly enhances video quality [46].
2. Microdebrider—Microdebrider is a powered
instrument. It is an extremely helpful surgical
tool in modern endoscopic sinus surgery [47].
Handpiece, interchangeable blades, and
machines are the components of microdebrider. The handpiece is connected with suction and irrigation source which is cylindrical
or piston drip in design (Fig.5.24). The blades
have cylindrical back part for easy connection
with handpiece. It contains two hollow shafts.
The outer shaft allows suction and irrigation
through and around the blades whereas the
inner shaft rotates or oscillates with in outer
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Fig. 5.24 Microdebrider hand piece, blades, and machine (Courtesy—Dr. Hitesh Verma, Associate Professor, AIIMS,
New Delhi, India)
G. Singh et al.
shaft. For surgical ease, blades are available in
wide range in term of size and angles. Straight
edge blades allow clear tissue cut without
injury to surrounding mucosa whereas serrated edge blades allow rapid tissue removal.
Frontal sinus and the deeper part of maxillary
sinus can be accessed by more angled blades.
Recent modication in design increases the
application of microdebrider such as inferior
turbinate reduction, correction of septal spur
[48]. The mode and speed can be control by
footplate of microdebrider.
Microdebrider acts by indrawn of soft tissue by the suction portal. This tissue is
sheared off by the revolving blade between
the inner and outer cannulas. Irrigation is
classically incorporated into the device,
applied by another set of tubing, and pumped
into the blade to assist the movement of
debrided tissue. The irrigation helps to prevent blockage of the device by the debrided
tissue. The slower the revolving speed of the
blade, the big is the tissue nibble. At higher
speed rates, the instrument becomes less
effective for debridement of tissue but it is
more effective for drilling of bone. Oscillation
mode is used for tissue debridement and it is
around 5000 rotations per minute. Other
mode is rotation, it is used for drilling and it
is around 15,000 rotations per minute. The
sheared bits of debrided tissue are sucked by
the suction effect. Microdebrider also
improves surgical eld by its suction and irrigation mechanism. The Advantages are the
preservation of surrounding healthy mucosa,
it allows precise tissue removal and decreases
surgical time [49]. It is commonly used for
the removal of polyp and tumor tissue of
nose and paranasal sinuses. Current technology advances have added cauterization of
bleeders by delivering bipolar cautery effect
via the end of the blade. These blades themselves are surrounded by layers of insulation
causing a sandwiching of the inner and outer
electrodes [50].
3. Coblator—Coblator term is originated from
“Controlled ablation”. It is a kind of bipolar
radiofrequency ablation that works at relatively low temperatures (typically 60–70C)
by unsettling molecular bonds and allowing
tissues to melt [51, 52]. Soft tissue melting
makes use of bipolar radiofrequency energy.
This energy is made to ow through a conductive medium like normal saline. When current
from radiofrequency probe passes through
saline medium it breaks saline into sodium
and chloride ions. These highly energized ions
form a plasma eld strong enough to break
organic molecular bonds within soft tissue
causing its dissolution. The excellent conduc-
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