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Glomus Jugulare
By
Dr. T. Balasubramanian M.S. D.L.O.
Synonyms:
Paraganglioma, Chemodectoma, Ganglia tympanica, Vascular
tumors of middle ear.
Definition: Glomus jugulare is
defined as a collection of ganglionic tissue within the temporal bone
in close relationship with the jugular bulb. The jugular bulb is
closely related to the floor of the middle ear cavity (i.e.
Hypotympanum).
History: Valentine in 1840
described this condition as ganglia tympanica. Guild
recognised its histological relationship with the carotid
body. Lattes and Waltner suggested that the ideal generic term
for these structures is non-chromaffin paraganglioma.
Paraganglia cells are derived from the neural crest and are found
widely distributed in the autonomic nervous system. Paraganglia
having negative chromaffin reaction are termed non - chromaffin
paraganglia. Guild in his anatomical studies on temporal bones
found that on an average three glomus bodies were found in them.
They were usually found in close relationship with the
tympanic branch of glossopharyngeal nerve or the auricular branch
of vagus. These bodies were supplied with non medullated sensory
fibers from the adjacent nerves. They are supplied by branches
from the ascending pharyngeal artery.
Eventhough the paraganglia cells are closely related to either the
tympanic branch of glossopharyngeal nerve or the auricular branch of
vagus, their position in the temporal bone is
highly variable. Commonly they are found in the adventitial
layer of the jugular bulb. In about 25% of cases they may be
found over the mucosa of the promontory. Histologically, they
resemble carotid body. It contains epitheloid cells interspaced
in a highly vascular stroma of capillary and precapillary
vessels. The proportion of the cellular and stromal components
vary. Guild classified glomus tumors into two types depending on
the amount of cellular and stromal components:
1. Cellular glomus bodies - when the cellular component is predominant
2. Vascular glomus bodies - when the vascular stromal
component predominates.
Their sizes could be variable, but mostly they are ovoid in shape.
Paragangliomas of the temporal bone are generally divided into those
that originate within the middle ear, glomus tympanicum tumors, and
those that originate within the jugular fossa, glomus jugulare
tumors. This latter term, however, is often used to refer to large
tumors where the origin is difficult to determine. The predominance of
the paraganglia within the jugular fossa likely accounts for the
increased frequency of tumors with this origin. Classification systems
that have been developed for temporal bone paragangliomas are used for
staging purposes. surgical planning, and comparison among different
therapeutic modalities.
Incidence: Glomus jugulare
occurs in about 1 in 100000 patients. It is 6 times more common
in females when compared to males.
Hereditary pattern: It shows autosomal dominant inheritance with
variable penetrance.
Endocrine activity: Eventhough these tumors are considered non
chromaffin paragangliomas with no endocrine activity, some cases with
endocrine activity by these tumors have been reported. It is
hence important to look for evidence of endocrine activity by urine
estimation of VMA (Vanillylmandelic acid).
Glomus tumors sometimes may show multicentric presentation i.e. present
in both ears, or in conjunction with other paragangliomas. The
carotid body being commonly the second site.
Pathophysiology: Glomus tumors
are encapsulated, highly vascular, and locally invasive tumors.
Inside the temporal bone they tend to expand along the pathway of least
resistance such as air cells, vascular lumen, skull base foramina and
eustachean tube. They also invade and erode bone in a lobular
fashion. The middle ear ossicles are commonly spared.
Initially skull base erosion occur in the region of jugular fossa and
postero inferior part of petrous bone. Later on extension occurs
to the mastoid and adjacent occipital bone.
The parenchyma of the paraganglia consists of 2 primary cell types.
Type I cells are more common and are typically round with indistinct
cell borders. Type II cells are smaller and irregularly shaped.
Presentation: These tumors are
slow growing, with very little symptoms. The diagnosis may easily
be missed. Infact the average delay between the onset of symptoms
and diagnosis varied from 6 years to 15 years. The first symptoms
generally follow middle ear involvement is easily overlooked.
Pulsatile tinnitus and conductive deafness are the
common presenting symptoms. A red mass behind an intact ear
drum (rising sun sign) may also be seen. In some 30% of
cases cranial nerve palsies are common. Facial nerve is affected
most commonly.
Fig showing glomus jugulare (Rising sun sign)
Presenting features of Gomus
jugulare:
1. Deafness - 69%
2. Middle ear mass - 75%
3. Pulsatile tinnitus - 55%
4. Imbalance - 8%
5. Otorrhoea - 5%
6. Facial palsy - 8%
7. Endocrine syndrome - 3%
8. Cranial nerve deficits
Hoarseness - 16%
Dysphagia - 16%
9. Headache - 15%
10. Visual disturbance - 6%
11. Presence of headache indicates intracranial extension
12. Dural sinuses may be involved may mimic sinus thrombosis
Clinical features: Otoscopic
examination reveals a characteristic, pulsatile, reddish-blue tumor
behind the tympanic membrane that often is the beginning of more
extensive findings (ie, the tip of the iceberg). When the drum is
examined under a microscope will show a pulsation of the reddish mass
behind the drum. On seigalisation the mass blanches. This
sign is known as Brown's sign. This is pathognomonic of
glomus tumor.
Audiologic examination reveals mixed conductive and sensorineural
hearing loss. The sensorineural component tends to be more significant
with larger tumors.
Classification:
Glasscock - Jackson classification of temporal bone paraganglioma:
1. Type I : Small tumor involving the jugular bulb, middle ear and
mastoid.
2. Type II: Tumor extending under the internal auditory canal.
There may be intracranial extension.
3. Type III: Tumor extending into the petrous apex. There may be
intracranial extension.
4. Type IV: Tumor extending beyond the petrous apex into the clivus and
infratemporal fossa. There may be intracranial extension.
The Fisch classification of glomus tumors is based on extension of the
tumor to surrounding anatomic structures and is closely related to
mortality and morbidity.
Fisch classification:
1. Type A tumor - Tumor limited to middle ear (carries the best
prognosis)
2. Type B tumor - Tumor limited to the tympanomastoid area with no
infralabyrinthine compartment involvement
3. Type C tumor - Tumor involving the infralabyrinthine
compartment of temporal bone with extension to petrous apex
This is divided into three types: C1, C2 and C3.
Type C1 - Tumor with limited involvement of the
vertical portion of the carotid canal
Type C2 - Tumor invading the vertical portion of the
carotid canal
Type C3 - Tumor invasion of the horizontal portion
of the carotid canal
4. Type D tumor has 2 types
Type D1 - Tumor with an intracranial extension
less than 2 cm in diameter
Type D2 - Tumor with an intracranial extension
greater than 2 cm in diameter
Diagramatic representation of glomus tumor
Investigations: Radiological
investigations help in the diagnosis.
Plain X ray skull: May show enlargement of lateral jugular foramen and
jugular fossa.
CT scan and Contrast MRI using Gadolinum enhancement is very helpful in
delineating tumor extension.
CT scan showing glomus tumor
Flow chart showing radiological investigations to study glomus
tumors in the middle ear
Applied anatomy of jugular bulb
area:
The
posterolateral portion of the foramen (pars venosa) contains the
jugular bulb, posterior meningeal artery, and cranial nerves X and XI.
The anteromedial portion (pars nervosa) contains the inferior petrosal
sinus and cranial nerve IX. The jugular bulb is situated between the
sigmoid sinus and the internal jugular vein. The lower cranial nerves
are situated medial to the medial wall of the jugular bulb. The
inferior petrosal sinus enters the medial aspect of the jugular bulb
via several channels anterior to cranial nerves IX, X, and XI.
Many
important structures are in proximity to the jugular bulb, including
the internal auditory canal, the posterior semicircular canal, the
middle ear, the medial external auditory canal, the facial nerve
(posterolaterally), and the ICA (anteriorly) within the carotid canal.
At the extracranial end of the jugular foramen, the ICA, internal
jugular vein, and cranial nerves VII, X, XI, and XII are within a 2-cm
area.
Treatment:
Treatment is mainly surgical. Complete resection of the mass
is curative. Since it is a highly vascular tumor pre op
intravascular embolisation may help to reduce bleeding during
surgery.
The particular surgical approach used to resect temporal bone
paragangliomas depends on the location and extent of the tumor.
Paragangliomas originating from the promontory of the middle ear and
isolated to the mesotympanum can be resected by elevating the tympanic
membrane and removing the tumor using microdissection techniques. If
the tumor extends into the hypotympanum or the mastoid, a
tympanomastoidectomy is performed and the tumor resected.
In extensive Fisch type 3 tumors the mass can be approached with help
from neurosurgeons. The skull base approach ensures better
exposure of the mass and facilitates complete resection.
Management of Fisch type 4 tumors is highly controversial.
Irradiation of the mass has been tried with very little effect.
Considering the slow growth rate of these tumors with a very long
doubling time, these patients are best left alone with symptomatic
treatment of the complications.
Complications of surgery:
Complications
of surgery include death, cranial nerve palsies, bleeding,
cerebrospinal fluid (CSF) leak, meningitis, uncontrollable
hypotension/hypertension, and tumor regrowth.
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