Keywords
Glomus tympanicum - Surgical approach - modified surgical technique
Introduction
Tympanic paragangliomas typically arise from the middle ear without involvement of
the jugular bulb or jugular foramen. They have a propensity to extend along the path
of least resistance to the epitympanum, hypotympanum, and Eustachian tube, or to expand
into the mastoid and external auditory canal. A reddish mass behind the tympanic membrane
with tinnitus along with conductive loss is the most common presentation. They are
benign and slow growing but produce disabling symptoms for which patients seek intervention.
Rosenwasser,[1] in 1945, was the first to report a carotid body tumor of the middle ear and mastoid.
The preferred term for middle ear paraganglioma is jugulotympanic paraganglioma. They
are the second most common type of temporal bone tumor after acoustic neuroma. The
female-to-male ratio is usually 4:1. Usually, high-resolution computed tomography
is used to study the extent of the tumor and eventual surgical planning.
Jugulotympanic paragangliomas, as per the Glasscock Jackson classification, are of
4 types. I - limited to promontory, II - filling the middle ear space, III - filling
the middle ear space and extending to mastoid, and IV - from the mastoid to fill the
external auditory canal and may extend anteriorly to the carotid artery.[2]
[3] Type-I tumors can be safely excised with the transcanal approach. Type-II and -III
jugulotympanic paragangliomas have been conventionally excised with the facial recess
approach. Tumors with grade-IV extension require standard canal wall mastoidectomy.
The facial recess approach, with its extension, was described to gain access to remove
the tumor from the retrotympanum and hypotympanic region.[4] However, there is restriction in tumor visualization due to limited exposure to
the tumor with increased chances of bleeding. The objective of the present paper is
to highlight our experience with a modified technique called postauricular transcanal
posterior tympanectomy for type-II and -III tumors. This technique is a head-on approach
for excision of the tumor.
Methods and Materials
This is a retrospective review of 34 cases of jugulotympanic paraganglioma treated
in a tertiary center between the period from 2009 to 2019. An approval of the institutional
ethics committee was obtained for the retrospective review of the cases. These patients
underwent surgical excision of the tumor using the modified technique. All the cases
were operated by the senior surgeon (N. K. P.). The cases of jugulotympanic paraganglioma
were reviewed by analyzing the files and charts with regard to clinical presentation,
diagnosis, and surgical management. Pulsatile tinnitus and hearing loss were the predominant
symptoms. The tumors were classified according to Glasscock and Jackson.[3] The patients were divided into three subgroups according to surgical procedure performed.
Group 1 included patients with type-1 tumors who underwent excision strictly via transcanal
approach (n = 2). Group 2 patients underwent surgery by the modified technique for type-II and
-III tumors (n = 29). Group 3 tumors underwent modified radical mastoidectomy for type-IV tumors
(n = 3). ([Table 1])
Table 1
Showing the Surgical approaches for Glomus Tympanicum
|
Surgical approach based on extent of tumor.
|
|
➢ Type I Transcanal excision
|
|
➢ Type II–III Facial recess or extended facial recess
|
|
➢ Modified - Postaural posterior tympanectomy approach
|
|
➢ Type IV may require a canal wall up mastoidectomy approach
|
Brief Overview of the Surgical Steps
Brief Overview of the Surgical Steps
The procedure was performed under general anesthesia. The patient was positioned supine,
with the head rotated to the opposite side. After sterile draping, a surgical microscope
was placed on the opposite of where the surgeon was. The skin was infiltrated with
2% lignocaine with 1:200,000 adrenaline in the postauricualr region and in the external
auditory canal following the Plester technique. A postaural Wilde incision was made,
and a large Palva flap elevated in addition to harvesting the temporalis facia. The
external auditory canal was entered by making a horizontal incision at the level of
the beginning of the bony canal. The tympanomeatal flap was elevated from 12° clock
to the 6° clock position till the sulcus tymapanicus and annulus dissected out. The
tympanomeatal flap was secured using an aluminum foil, which was held in place with
the help of corrugated drain and a mastoid rertractor. The postauricular approach
and anterior based periosteal flap enable the surgeon to have additional exposure.
([Fig. 1])
Fig. 1 Edited showing the tumor after elevation of the tympanomeatal flap.
The extent and margin of the tumor were examined all around. The drilling commenced
in the posterosuperior region of the external auditory canal and the outer attic wall
to expose the ossicles. [Fig. 2] The tumor could then be easily dissected around the ossicles, thus preserving the
hearing. Thereafter, the drilling was performed judiciously in the posteroinferior
part as the facial nerve runs lateral to the tympanic annulus in this region. The
hypotympanic air cells were then exposed, and the tumor was delineated all around.
Once the tumor margins were clearly delineated, a bipolar cautery was used to control
the feeding vessels. [Fig. 3] This shrinks the primary lesion sufficiently and provides hemostasis. The devascularized
lesion was, thereafter, dissected from the promontory by a sharp dissection. [Fig. 4]. At times, the residual bleeding from the bony channels on the promontory could
be effectively controlled by oxidized cellulose (Surgicel - Ethicon Inc., Somerville,
NJ, USA). [Fig. 5]. The surgical video of the procedure is enclosed ([video 1]).
Video 1 Video of the surgical procedure
Fig. 2 Edited showing the drilling in the posterosuperior region of the external auditory
canal.
Fig. 3 Edited showing the application of the bipolar diathermy for shrinking the tumor.
Fig. 4 Edited showing the dissection of the lesion from the promontory. The incudostapedial
joint and stapedius tendon are seen.
Fig. 5 Edited showing the ossicular chain, stapedius tendon and round window niche after
tumor removal.
If the tumor extended medial to the ossicles, the incus was dislocated from the stapes
and removed to gain access. Tympanoplasty was performed, and the canal was packed
with medicated gel film. The patients were alerted regarding the possibility of bleeding,
hearing loss, facial nerve paralysis, taste disturbance, and tympanic membrane perforation.
The follow-up protocol consisted of a computed tomography of the temporal bone with
contrast at the end of 3 months to rule out any recurrence of the tumor. Those with
persistent symptoms of tinnitus underwent computed tomography after 6 months
Results
A total number of 34 jugulotympanic paragangliomas were operated. Out of 34 patients,
8 were male and 26 were female. The modified technique was used in 29 patients. Only
two cases were operated on with a classical transcanal approach. Canal wall down mastoidectomy
was required in three cases. All the cases were successfully operated. Only 2 cases
(2/29) had recurrence with return of tinnitus and conductive hearing loss. A computerized
tomography scan confirmed the presence of tumor in the middle ear. Revision surgery
in the two patients resulted in complete removal of the lesion. None of the patients
required postoperative gamma knife therapy or radiotherapy.
Two patients had tympanic membrane perforation, for which they underwent repair of
the tympanic membrane.
None of the patients had bleeding, facial paralysis, or taste disturbances.
All the patients had resolution of tinnitus after surgery. That is indicative of the
completeness of tumor excision. A repeat computerized scan also confirmed the removal
of the tumor. ([Fig. 6 a] and [b])
Fig. 6 (a) Edited computerized scan in axial plane showing the soft tissue opacity in the middle
ear surrounding the ossicles. (b) edited post operative scan in axial plane showing the complete disappearance of
the lesion
Hearing results: The hearing results are shown in [Table 2]. There was a significant difference in the hearing thresholds after surgery. The
postoperative improvement was around 19%.
Table 2
Showing the hearing thresholds before and after surgical excision. (n = 29)
|
Hearing threshold
|
Preoperative
|
Postoperative
|
P-value
|
|
49.52 ± 17.22 dB
|
40.53 ± 17.34 dB
|
0.001 [*]
|
*
P-value is derived using the Wilcoxon test
* statistical significance (p < 0.05)
Discussion
It was Guild, in 1941, who described glomic tissue for vascularized tissue in the
middle ear over the promontory and jugular bulb.[5] The glomus tympanicum tumors are typically located in the mesotympanum over the
promontory, with propensity to expand into the mastoid and external auditory canal.
The patients typically present with hearing loss and tinnitus. There can be otalgia,
and vagal or hypoglossal palsy due to the mass effect on the surrounding structures.
A complete excision is ensured by identifying the entire margin of tumor extension.
The management of jugulotympanic paragangliomas stand divided with the current standard
of care. Surgical management of glomus tympanicum depends upon the stage of the tumor.
Tumors strictly over the promontory are generally approached by the transcanal route.
Recently, endoscopes have also been used for small tumors, with excellent results.[6] Endoscopic ear surgery has also revolutionized transcanal surgery for these lesions.
Pollak et al.[6] described a removal of tympanic paraganglioma exclusively with endoscopes. Endoscopic
ear surgery enhances visualization to ensure complete removal of smaller lesions.
Mohammed et al.[7] also reported a case of endoscopic excision of tympanic paraganglioma. Endoscopic
ear surgery, thus, could be a good tool for smaller lesions. Endoscopes enable the
surgeon to have three-dimensional anatomy of the middle ear cleft. However, for larger
lesions, a transcanal endoscopy may not be feasible for complete extirpation of the
lesion.
A facial recess approach can still be used when the computerized tomography localizes
it in the mesotympanum. Traditionally, the removal of type-II or type-III tumors is
accomplished through the extended facial recess approach described by House and Glascock.[4] The extended facial recess is a time tested and safe approach for the management
of tympanic paragangliomas. The approach preserves the posterior canal wall and is
supposed to provide exposure through a facial recess approach. The advantages of this
approach are clear demarcation of the entire course of vertical segment of the facial
nerve prior to handling of the tumor, thus ensuring safety. Occasionally, one of the
limitations of the facial recess approach could be the presence of continuous oozing
at the time of surgery. This may prompt the surgeon to remove the canal wall or resort
to canal wall mastoidectomy for tumor removal.
We have, therefore, modified our technique in glomus tympanicum class II and III,
in which we use the postauricular transcanal posterior tympanectomy approach, the
surgical steps of which have already been described. Our technique obviates the need
to convert to a canal wall mastoidectomy in cases of imminent difficulty with the
facial recess approach. This approach gives a head-on approach in addition to wide
and adequate exposure to dissect tumor from the attic, mesotympanum, and hypotympanum.
The tumors extending into the hypotympanum are approached by extended hypotympanic
access by drilling the anteroinferior canal wall. A wider access also ensures easy
maneuverability of the bipolar cautery forceps used for dissection and making the
tumor avascular. This results in complete excision of the tumor. ([Figs. 1] and [2]). Some surgeons advocate the use of fiber-based laser system, which allows for accurate
delivery of laser pulses to the tumor margins, thus being useful for tumor dissection.
In our opinion, a microbipolar forceps is quite convenient to use.
The extension of glomus tympanicum to the hypotympanum is a difficult issue. The transcanal
approach may have to be combined with endoscopic assisted visualization. Some of them
may require mastoidectomy with retrofacial hypotympanotomy. Our technique also facilitates
a hypotympanum approach, as described by Shambaugh[8] or Farrior.[9] The hypotympanic access is achieved by removing the inferior part of the posterior
bony external auditory canal.[10] The surgeon must exercise caution here to avoid injury to the mastoid (vertical
segment) of the facial nerve. Our technique (PT2) is, therefore, unique in providing wide exposure of the mesotympanum, epitympanum,
and hypotympanum for achieving complete excision of the tumor. This surgical procedure
is safe and provides better anterior and inferior dissection of tumor without compromising
the visualization of the tumor margins. Another advantage of our approach is a wider
canal for adequate postoperative examination. The ossicular chain and tympanic membrane
repair can also be done with satisfactory outcomes. These added advantages make this
technique an ideal approach for removal of glomus tympanicum tumors. This technique
of removal of jugulotympanic paragangliomas has not been reported earlier in the literature.
We came across only two cases who had recurrence in 2 years of follow-up. Both patients
required revision surgery. None of the patients had any tympanic membrane perforation
or cholesteatoma. No patient required gamma knife therapy.
Conclusions
A complete surgical removal is the treatment of choice in tympanic paragangliomas.
The preoperative imaging allows for exact localization of the tumor and surgical planning.
The modified technique of the postauricular transcanal posterior tympanectomy approach,
nicknamed PT2, is ideally suited for types II and III glomus tympanicum tumors. This technique
provides an adequate exposure for complete excision of jugulotympanic paragangliomas.
