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\begin{document}

\title{Endopharyngeal Ultrasound}



\author[1]{Taha Mur}%
\author[1]{Osamu Sakai}%
\author[1]{Lauren Tracy}%
\author[1]{Kei Suzuki}%
\author[2,3]{Daniel Faden}%
\affil[1]{Boston Medical Center}%
\affil[2]{Harvard Medical School}%
\affil[3]{Massachusetts Eye and Ear Infirmary}%


\vspace{-1em}



  
  \date{June 07, 2024}


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Key Points:

\begin{itemize}
\tightlist
\item
  We describe a novel procedure, Endopharyngeal Ultrasound (EPhUS) and
  EPhUS-guided FNA
\item
  EPhUS requires an operator and an assistant, can be performed
  transnasal or transoral, and utilizes a Endoscopic Ultrasonography
  Bronchoscope
\item
  EPhUS is a safe and effective method for biopsy of deep space neck
  masses inaccessible to transcutaneous FNA
\end{itemize}

Key Words: Endoscopic, Ultrasound, Fine needle aspiration, Neck mass,
Biopsy, minimally invasive

Ethical Considerations: The patient presented below was informed that
this procedure has not been reported in the past and agreed to proceed
following standard informed consent. The patient consented to having
their case published in the literature.

\textbf{INTRODUCTION:}

Ultrasound (US) has become an integral part of the practice of medicine
due in part to its soft tissue resolution, cost effectiveness, ability
to measure vessel flow and, perhaps most relevant to head and neck
surgeons, ease of use in the clinical setting in conjunction with fine
needle aspiration (FNA). Thus, it is no surprise that US has gained
significant traction in head and neck surgery in both the clinical and
operative setting for imaging and biopsies of soft tissue lesions of the
lateral and central neck(2). The development of US probes attached to or
passed through endoscopes has allowed for the development of endoscopic
US. For instance, endobronchial ultrasound (EBUS) is a bronchoscopic
technique that utilizes US to visualize structures in the trachea and
paratracheal soft tissues and has become the modality of choice for
mediastinal lymph node biopsy. In EBUS, the endoscope is equipped with
an US at the tip, allowing for image guided endoscopic FNA. The EBUS
system was first introduced in the 1990's as a minimally invasive option
compared to mediastinoscopy and open biopsy. Large series have
demonstrated the safety and cost effectiveness of EBUS with a major
complication rate of well under 1\%(3).

Transcutaneous central and lateral neck US, in both the outpatient
clinic and operating room, is commonplace in head and neck surgery.
However, for the upper aerodigestive track, flexible endoscope-based US
techniques and approaches have not yet been well developed or described.
Adapting existing endoscopic based US techniques, here, we describe
flexible endopharyngeal ultrasound (EPhUS) and the EPhUS guided FNA.

\textbf{MATERIALS/METHODS}

A 61-year-old woman was referred to the general Otolaryngology clinic
with the incidental finding of a left neck mass identified on CT scan.
Contrast-enhanced CT revealed a 3cm low attenuating lesion with a
punctate calcification, displacing the internal and external carotid
arteries anteromedially and internal jugular vein
posterolaterally(Figure 1A). The differential diagnosis included
metastatic lymphadenopathy or neurogenic tumor. Given these findings,
the patient was referred to interventional radiology for an image guided
biopsy. However, upon review, the interventional radiology team deferred
transcutaneous FNA given proximity of the mass to the great vessels. The
patient was then referred to the head and neck surgical oncology clinic
of the senior author for management. MRI with and without contrast
demonstrated a rim-enhancing, predominantly non-enhancing lesion with a
nodular enhancement at its medial portion, and foci of susceptibility
effect, suggestive of microhemorrhage(Figures 1B, C). Although,
schwannoma was high on the differential diagnosis, calcifications were
felt to be an unusual finding. The differential diagnosis included
metastatic lesions, particularly from the thyroid, and neurogenic tumor.
In office US confirmed that transcutaneous biopsy was not possible due
to the location of the internal and external carotid arteries in the
line of transcutaneous US-guided FNA. Open biopsy was felt to be a poor
choice due to potential for nerve injury in the case of a neurogenic
tumor, in addition to standard reasons to avoid open surgical biopsies
in cases of suspected neoplasm (scar, risk of seeding tumor, cranial
nerve injury). Options of observation and EPhUS were offered and after
informed consent, EPhUS was selected.

The patient was given general anesthesia and intubated orally. A tonsil
gag was placed to expose the pharynx. An \emph{Olympus BF-UC180F
Endoscopic Ultrasonography Bronchoscope} (Tokyo, Japan) was placed
transorally into the pharynx(Figure 1D). The endoscope is equipped with
a 7.5 MHz convex ultrasound probe(Figure 1E). The angle of view is 90
degrees and the direction of view is 35 degrees forward and oblique. The
tip of this scope contains a balloon, which assists with acoustic
coupling of the ultrasound, however this is of little utility in the
pharynx. A working channel allows passage of a needle for FNA. The
endoscope, processing tower and monitor system allow duel display of
both the ultrasound and endoscopic images, including Doppler. Both
transnasal and transoral EPhUS are possible. In our experience both
require two people: an endoscopist and an assistant to hold the
endoscope in contact with the pharyngeal wall. The endoscope is passed
into the pharynx and then brought into contact with the pharyngeal
mucosa. Real time ultrasonographic imaging is then performed. In this
case example, the lesion in question, with the internal and external
carotid arteries on the lateral surface, are clearly identifiable
(Figure 1F). After confirmation of the lesion, FNA can be performed
(Figure 1G).

This needle used here is a retractable, 22g-g beveled, needle with a
stylet, which allows clearance of plugs. The external surface of the
needle is grooved, rendering it more hyperechoic, improving US
visualization. Once the target mass is identified, the needle is
advanced through the channel of the bronchoscope. Although the needle
can be extended to a length of 40mm, intrinsic safety mechanisms of the
device prevent excessive needle protrusion. Suction can be applied with
a 20-ml VacLoc syringe as needed. When an adequate biopsy is obtained,
the entire needle system is then withdrawn and the aspirated specimen is
removed by pushing preservative through the lumen. Both on-site and
final pathology confirmed the diagnosis of nerve sheath tumor. There was
minimal blood loss. The patient was observed in the post-anesthesia unit
and discharged in stable condition after examination confirmed no voice
changes, dysphagia or shortness of breath. When seen in follow up, she
was asymptomatic.

\textbf{DISCUSSION}

There are sparse descriptions in the literature regarding endopharyngeal
ultrasonographic techniques8,9,10. All such descriptions have employed
rigid endocavitary probes, which

suffer from limitations in: 1) the anatomic regions accessible to line
of sight through the oral

aperture and 2) cumbersome size. Here, we present EPhus and EPhUS-guided
FNA as a safe and minimally invasive technique for assessing and
sampling parapharyngeal lesions not accessible by transcutaneous FNA.
While EPhUS requires specialized equipment, the procedure is straight
forward for surgeons familiar with endoscopy of the upper aerodigestive
tract and ultrasonography. Most hospitals which provide multispecialty
care are equipped with the necessary endoscopes to perform EPhUS. In
this case example, a lesion of the carotid space, was successfully
visualized and sampled by EPhUS. Additional spaces, which have
traditionally proved hard to access by transcutaneous image (US or CT)
guided FNA, yet are accessible by EPhUS include the parapharyngeal,
retropharyngeal and pterygomandibular spaces (Figures 2A-B).

In conclusion, EPhUS and EPhUS guided FNA can be a safe, minimally
invasive approach for visualization and biopsy of lesions in the
parapharyngeal, retropharyngeal and pterygomandibular spaces, which have
traditionally been difficult to access with transcutaneous image guided
FNA.

\textbf{REFERENCES} :

\begin{enumerate}
\tightlist
\item
  Kane D, Grassi W, Sturrock R, Balint PV. A brief history of
  musculoskeletal ultrasound:`From bats and ships to babies and hips'.
  Rheumatology. 2004 Jul 1;43(7):931-3.
\item
  Mcivor NP, Freeman JL, Salem S, Elden L, Noyek AM, Bedard YC.
  Ultrasonography and ultrasound-guided fine-needle aspiration biopsy of
  head and neck lesions: a surgical perspective. The Laryngoscope. 1994
  Jun;104(6):669-74.
\item
  Rintoul RC, Glover MJ, Jackson C, Hughes V, Tournoy KG, Dooms C,
  Annema JT, Sharples LD. Cost effectiveness of endosonography versus
  surgical staging in potentially resectable lung cancer: a health
  economics analysis of the ASTER trial from a European perspective.
  Thorax. 2014 Jul 1;69(7):679-81.
\item
  Gu P, Zhao YZ, Jiang LY, Zhang W, Xin Y, Han BH. Endobronchial
  ultrasound-guided transbronchial needle aspiration for staging of lung
  cancer: a systematic review and meta-analysis. European journal of
  cancer. 2009 May 1;45(8):1389-96.
\item
  Steinfort DP, Hew MJ, Irving LB. Bronchoscopic evaluation of the
  mediastinum using endobronchial ultrasound: a description of the first
  216 cases carried out at an Australian tertiary hospital. Internal
  medicine journal. 2011 Dec;41(12):815-24.
\item
  Fornage BD, Edeiken BS, Clayman GL. Use of transoral sonography with
  an endocavitary transducer in diagnosis, fine-needle aspiration
  biopsy, and intraoperative localization of retropharyngeal masses.
  American Journal of Roentgenology. 2014 May;202(5):W481-6.
\end{enumerate}

Figure legends

Figure 1. A 61-year-old woman with an incidentally found left neck mass.

\begin{enumerate}
\tightlist
\item
  Contrast-enhanced CT demonstrates a well-demarcated lesion
  (\emph{arrows} ) with a punctate calcification (\emph{arrowhead} )
  displacing the internal and external carotid arteries anteromedially
  and internal jugular vein posterolaterally. Note the lesion is
  surrounded by great vessels, preventing percutaneous biopsy.
\item
  Post-contrast fat-suppressed T1-weighted MR image demonstrates a
  rim-enhancing, predominantly non-enhancing lesion (\emph{arrows} )
  with a nodular enhancement (\emph{arrowhead} ) at its medial portion,
  which may be an ideal site for biopsy.
\item
  Fast-field echo MR image demonstrates foci of susceptibility effect
  (\emph{arrowheads} ) within the lesion (\emph{arrows} ), suggestive of
  microhemorrhage.
\item
  A Crow-Davis is used to expose the pharynx. An assistant works to keep
  the bronchoscope in position.
\item
  The endoscope is equipped with a 7.5 MHz convex ultrasound probe and a
  needle that is delivered through the working channel of the scope.
\item
  Endoscopic Doppler ultrasonography demonstrates the lesion
  (\emph{arrows} ) and surrounding internal and external carotid vessels
  (\emph{arrowheads} ).
\item
  Intra-procedure ultrasonography demonstrates needle (\emph{arrows} )
  inserted into the lesion for sampling.
\end{enumerate}

Figure 2. Examples of lesions that may be accessed by EPhUS guided FNA

\begin{enumerate}
\tightlist
\item
  A 53-year-old man with laryngeal cancer. Contrast-enhanced CT
  demonstrates a borderline-enlarged round retropharyngeal node with
  ill-defined boundary (\emph{arrow} ).
\item
  A 73-year-old woman with mandibular cancer status post resection and
  reconstruction. Contrast-enhanced CT demonstrates a peripherally
  enhancing lesion (\emph{arrow} ) at the medial and posterior aspect of
  the right medial pterygoid muscle, concerning for recurrence.
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