GLOMUS TUMOUR

It is the most common benign neoplasm of middle ear and
is so-named because of its origin from the glomus bodies.
The latter resemble carotid body in structure and are
found in the dome of jugular bulb or on the promontory
along the course of tympanic branch of IXth cranial nerve
(Jacobson's nerve). The tumour consists of paraganglionic
cells derived from the neural crest.
Aetiology and Pathology
The tumour is often seen in the middle age (40-50
rears). Females are affected five times more.
It is a benign, non-encapsulated but extremely vascular
neoplasm. Its rate of growth is very slow and several
'ears may pass before there is any change from the initial
symptoms. Tumour is locally invasive.
Microscopically, it shows masses or sheets of epithelial
cells which have large nuclei and a granular cytoplasm.
There is abundance of thin-walled blood sinusoids with
no contractile muscle coat, accounting for profuse bleedIng
from the tumours.
For purposes of diagnosis and treatment, two types are
differentiated.
1. Glomus jugulare. They arise from the dome of
Jugular bulb, invade the hypotympanum and jugular foramen,
causing neurological signs of IXth to XlIth cranial
nerve involvement. They may compress jugular vein or
Invade its lumen .
2. Glomus tympanicum. They arise from the promonory
of the middle ear and cause aural symptoms, some"
Imes with facial paralysis.
Spread of Glomus Tumour
1. Tumo ur may initially fill the middle ear and later
perforate through the tympanic membrane to present
as a vascular polyp.
2. It may invade labyrinth, petrous pyramid and the
mastoid.
3. It may invade jugular foramen and the base of skull,
causing IXth to Xllth cranial nerve palsies.
4. By spread through eustachian tube, it may present in
the nasopharynx.
5. It may spread intracranially to the posterior and
middle cranial fossae.
6. Metastatic spread to lungs and bones is rare, but
seen in 4% of cases. Metastatic lymph node enlargement
can also occu r.
Clinical Features
In 90% of cases, symptoms pertain to the ear.
(a) When tumour is intra tympanic. Earliest symptoms
are deafness and tinnitus. Deafness is conductive
and slowly progressive. TlOnitus is pulsatile and of swishing
character, synchronous with pulse, and can be temporarily
stopped by carotid pressure .
Otoscopy shows a red reflex through intact tympanic
membrane. "Rising sun" appearance is seen when tumour
arises from the floor of middle ear. Sometimes, tympanic
membrane appears bluish and may be bulging.
"Pulsation sign" (Brown's sign) is positive, i.e. when ear
canal pressure is raised with Siegle's speculum, tumour
pulsates vigorously and then blanches; reverse happens
with release of pressure.
(b) When tumour presents as a polyp. In addition
to deafness and tinnitus, there is history of profuse bleeding
(rom the ear either spontaneously or on attempts to
clean it.
Dizziness or vertigo and facial paralysis may appear.
Earache is less common than in carcinoma of-the external
and middle ear, and helps to differentiate ie.
Otorrhoea may occur due to secondary infection and
the condition may simulate chronic suppurative otitis
media with polyp.
Examination reveals a red, vascular polyp filling the
meatus. It bleeds readily and profusely on manipulation
or at biopsy.
Cranial nerve palsies. This is a late fe ature appearing
several years after aural symptoms. IXth to XIIth cranial
nerves may be paralysed. There is dysphagia and hoarseness
with unilateral paralysis of the soft palate, pharynx
and voca l cord with weakness of the trapezius and sternomas
toid muscles.
Tumour may present as a mass over the mastoid or in
the nasopharynx.
Signs of intracranial invo lvement may also occur.
Audible bruit. At a ll stages, ausc ultat ion with
stethoscope over the mas toid may reveal systolic bruit.
Some glomus tumours secrete catecholamines and produce
symptoms like headache, sweating, palpitation, hypertension
and anxiety, and require further investigat ions.
Rule of lOs. Remember that 10% of the tumou rs are
familial, 10% multicentric and up to 10% functional, i.e.
they secrete catecholamines.
Diagnosis
In addition to thorough history and physical examination,
the patient is checked-up to find out the extent of
tumour, other associated glomus tumours, and serum levels
of catecholamines or their break-down products in urine
(vanillylmandelic acid, metanephrine, etc.). Investigations
include:
CT scan-head. Using bone window, 1 mm thin sections
are cut. It helps to distir,guish glomus tympanicum
from the glomus jugu lare tumour by iden tification of
caroticojugular spine which is eroded in the latter. CT
scan also helps to differentiate it from the abe rrant
carotid artery, high or dehiscent jugular bulb.
MRI. It gives soft tissue extent of tumour .. Magnetic
resonance angiography and venography further help to
delineate invasion of jugular bulb and vein or compression
of the carotid artery.
Four vessel angiography. It is useful to find out extent
of tumour and compression of internal carotid artery. Also
useful in finding other carotid body tumours and embolisat
ion of the tumour, if that becomes necessary. If the case
needs surgical treatment, brain perfusion studies and adequacy
of contralateral internal carotid artery and circle of
Willis are also assessed. Diagnosis of glomus tumour is
made on clinical and radiographic findings. Diagnostic
biopsy is not done as the tumour is highly vasc ular.
Treatment
It consists of:
1. Surgical removal.
2. Rad iation.
3. Embolisation.
4. Combination of the above techniques.
Dependin g on the extent of tumour, surgical removal
may be done through transmeatal, transmasto id or skull
base approach.
Radiat ion treatment does not cure the tumour but may
reduce its vascu larity and arrest its growth . Radiation is
used for inoperable tumours, residual tumours, recurrences
after surgery or for older individuals where extensive sku ll
base surgery is not indicated.
Embolisation is used to reduce the vascularity of
tumour before surgery, or is the sole treatment in inoperable
patients who have received radiation.