Schwannnomas - Revised 2 - Word
Schwannnomas - Revised 2 - Word
Schwannnomas - Revised 2 - Word
Prankur Verma*, Jeyashanth Riju*, Natarajan Ramalingam*, Rubine Zeinuddin*, Antony Paulose, Sherin
Susheel**, Meera Thomas**, Rajan Sundaresan***, Rajiv Michael*, Amit Tirkey*, Aparna Irodi****,
Kiranmayi C****
* Department of Head and Neck Surgery, Christian Medical College, Vellore, Tamil Nadu, India, 632002
** Department of Pathology, Christian Medical College, Vellore, Tamil Nadu, India, 632002
*** Division of Skull Base Surgery, Department of E.N.T., Christian Medical College, Vellore, Tamil Nadu,
India, 632002
**** Department of Radiodiagnosis, Christian Medical College, Vellore, Tamil Nadu, India, 632002
Corresponding author: Jeyashanth Riju M.S., F.H.N.S.O., Assistant Professor and In-charge, Department
of Head and Neck Surgery Unit- 1, Christian Medical College, Vellore. Phone: +914162282075,
Funding statement
This work received no funding or any specific grant from any source.
Approval for the study was obtained from the Ethics Committee, Institutional Review Board, Christian
Medical College, Vellore, Tamil Nadu, India, 632002. IRB Number: 15156 dated 25/01/2023
ABSTRACT
Introduction: Schwannomas are rare benign neurogenic tumours. About 25 - 45 % of extra cranial
schwannomas are found in the head and neck region. In head and neck, they can arise from various cranial,
peripheral and autonomic nerves. Due to this, they have varied clinical presentations.
Material and Methods: This retrospective cohort includes 97 patients diagnosed with extra cranial head and
neck schwannoma, and operated in the Otolaryngology and Head & Neck Surgery department, from 2013 till
2022 were recruited as a retrospective cohort. The parameters observed were the age and gender distribution,
location, nerve of origin, size, pressure symptoms, cranial palsies, post operative symptoms, recurrence and
complications. The data were collected from the electronic records of the institute.
Results: The median age of study population was 36 years among them. 51 patients were menale and 46
were womenfemales. The most common tumour location was parapharynxs were varied. The patients had
varied head and neck symptoms of which 23.7% patients had nerve pareses pre operativelyat presentation. A
variety of surgical approaches were used. 22 patients developed Nnew onset cranial nerve pareses immediate
Conclusions: Extra cranial schwannomas are uncommon neoplasms and have varied presentations.
Comprehensive evaluation with appropriate imaging should be done in all cases. Though benign, patients
can present with nerve paresis. Recurrence is uncommon after complete resection.
Keywords: Sschwannoma, Nerve Sheath Neoplasms, Head and Neck Neoplasmhead and neck
Schwannomas are rare benign neurogenic tumours. Along with neurofibroma, they constitute
one of the two most common benign nerve sheath tumours(1). It is reported that 25–45% of extra cranial non
vestibular schwannomas are found to be in the head and neck region(2). They are encapsulated,
slow-growing tumors that arise from Schwann cells of myelinated nerves and so can be found arising from
various cranial, peripheral, and autonomic nerves. They can arise in a variety of locations in the head and
neck region, given the abundance of various nerves, and thus they have varied presentations. The clinical
signs and symptoms vary according to the size and location of the tumour, and the nerve of origin(3). Such
varied presentations pose diagnostic and therepeutic challenges. Surgical resection is the mainstay of
treatment.
This study describes the clinico pathological presentation and outcome following surgical resection in a set
of 97 patients with extra cranial head and neck schwannomas arising in a variety of locations and study the
post operative course. This series is supposed to be one of the largest of its kind till now, to the best of our
knowledge.
Methodology
A total of 97 patients diagnosed with extra cranial non vestibular schwannomas, operated between January
2013 till December 2022 in the Department of Otorhinolaryngology and Head and Neck Surgery and The
Department of otorhinolaryngology of the Christian Medical College, Vellore, India, were recruited as a
retrospective cohort. Those with a history of radiotherapy to the head and neck region, those who presented
with a recurrent schwannoma, and those who did not undergo surgical intervention were excluded from the
study. Ethical clearance was obtained from theStudy was approved by Institutional Review Board before
The objective of the study was to investigate the clinico pathological features of various extra cranial non
vestibular schwannomas; and to analyse the immediate and long termlong-term complications following the
surgery.
The parameters that were analysed were the age and gender distribution, location and side of the tumour, the
nerve of origin. The symptomatology due to the mass effect and nerve dysfunction was noted. Local
examination findings with emphasis on cranial and autonomic nerve functions were recorded. DPost
operative diagnostic workup including imaging and cytopathology were noted. Surgical approaches to the
tumour were noted. Various immuno-histochemical markers that aided in the pathology reporting were
studied. Post operative complications that included occurrence of nerve dysfunction were noted. The
patient’ss’ routinely followed after up upto 6 months or 1 year post surgery, or earlier, if symptomatic, was
studied. Further follow up was based if symptomaticon symptom or at the discretion of the treating physician
was noted. The data were collected from the electronic records of the institute and entered in the spreadsheet
RESULTS
The study included 97 patientss studied, of them, 52.6% were male and 47.4% were female. Overall median
age was 36 years, the median age of males being 34 and that of females being 40 years. Excluding the
tumours situated midline, 42.3% of the tumours were present on the right side, while 53.6% tumours were on
the left, and 1 of the patient had bilateral tumours. The tumour predominantly involved the left side in men
(62.5%) but was evenly distributed in females(Table 1). Considering the location of the tumours; 49.5%
were parapharyngeal, 19.6% were cervical, 10.3% arose from the parotid region, 6.2% were located in the
nose or paranasal sinus region, and 14.4% from other unusual sites (Fig 1).like supra glottis, nasal cavity,
external auditory canal, palate, base of the tongue and medial canthus(Fig 1).
NERVE OF ORIGIN?
The most common presenting symptom was a swelling in the neck or mouth (68%). Pain over the side or site
of the mass lesion was noted in 20.6% of the patients presented with pain over the side or site of the mass
lesion. Out of the 67 patients with deep neck space (cervical or parapharyngeal) schwannomas, 19% had
change in voice. 19% presented with difficulty in swallowing. We noticed Ear related complaints were
present in 10.3% of the total patients. 15.5% of the patients had symptoms related to a nerve paresis like
voice change, facial weakness, or coughing just after swallowing foodon having liquid diet or facial
weakness(IS IT CORRECT? WHY DO WE HAVE FACIAL WEAKNESS DATA HERE). Among those
with schwanomma arising from the facial nerve, 33.3% had facial nerve weakness (4 out of 12), 3 (25%) had
ear healed related complaints, 1 had headache as the sole symptom, while one was incidentally detected on
imaging. Among the 6 with tumour arising from the nose or paranasal sinuses, nasal obstruction was present
in 2 cases , nasal bleeding in 1 case, and loosening of teeth in 1 case. Ear related complaints were present in
10.3% of the total patients. Other uncommon presentations that were related to the location of the tumour
were nasal block, tingling sensation over the tongue, facial pain, vision loss, oral bleeding, tingling sensation
in the arm, or swelling in the medial canthal region(MENTION PERCENTAGE IN BRACKET eg nasal
Out of the deep neck space schwnnomasschwannomas, neck swelling was noted in 88% and oropharyngeal
mass in 47.6%. Among those with facial nerve schwannoma, 58.3% (7/12) had facial swelling and
33.3%(4/12) had facial paresis. Uncommon locations of the tumour were supra glottis, nasal cavity, external
auditory canal, palate, base of the tongue and medial canthus (Fig 1).
Various single or multiple nerve paresis were found in 23.7% of the total patients on presentation. Among
them, the most commonly involved nerve was vagal (43.5%) followed by hypoglossal nerve (34.8%). A
total of 34.8% of those with nerve paresis had multiple nerve involvement (Table 2).
Contrast enhanced Computed Tomography and Magnetic Resonance Imaging were the mainstay of cross
sectional imaging methods that were performed in 92.8% of the cases; in the rest, ultrasonography was used.
The mean size of the tumour was 5.4 cm. Radiological investigations could categorise 68.9% of the tumours
Pre operative fine needle aspiration cytology was performed in 54.6%. Among them, 49.1% showed spindle
cell/ neurogenic origin, 11.3% showed benign tumour, 1.9% showed necrosis. In 35.8%, FNAC material was
inadequate for characterisation. 3 cases were hybrid nerve sheath tumours characterised as schwannoma-
neurofibroma.
subluxation approach (62 cases), transcervical with mandibulotomy (7 cases), trans parotid (13 cases), trans
oral approach (10 cases, 2 had laser assisted excision and others(CORRECT?) had TOUSS assisted excision)
and endonasal (5 cases) (Fig 2). Uncommon approaches that were used were sub occipital, transmastoid,
craniotomies and Fisch type A depending upon the location of the tumour. None of the patients who
underwent surgery required tracheostomy except for one with a supraglottic schwannoma that required
temporary tracheostomy, who was successfully weaned off. During the immediate post operative period,
Nasogastric tube feeding was needed in 10.3% of the patients due to aspiration while 3.1% of them required
it in the long term. All these were related to parapharyngeal schwannoma excision. Fig 3 shows __(CONT
FIND IMAGE)
Among the immunohistochemical markers, S100 and SOX10 were used as an aid in the diagnosis in 17.5%
and 14.4% cases respectively. CD 34 was positive in 4 out of 7 cases (57.1%). Other markers that turned
negative included SMA (3 cases), synaptophysin (1 case), desmin (1 case), EMA (2 cases). MIB 1 index was
performed in 9 cases in whom the median value was 6% (range 1 - 30%). Hybrid nerve sheath tumours was
noted in 3.1%.
Immediately following the surgery, 1 patient required re exploration and evacuation of haematoma, and one
patient developed surgical site infection that was managed conservatively with antibiotics.
Among the new onset nerve dysfunctions (Fig 4), 9 developed Horner’s syndrome, 8 developed hypoglossal
palsy, 13 developed vagal palsy, 10 developed facial paresis(among them 8 were facial nerve schwannomas)
and 2 had trigeminal paresis. Among those whom underwent deep neck space schwannoma excision,
dysphonia, aspiration and dysphagia was present noted in 25.4% (17 cases), 17.9% (12 cases) and 9% (6
Analysing the long term neural dysfunction and morbidity among the deep neck space schwannomas;
dysphonia, aspiration and dysphagia was present in 7.5% (5 cases), 6% (4 cases), and 3% (2 cases)
respectively. One case patient developed trismus. Two had chronic pain at the surgical site and temporo-
mandibular joint respectively. In those patients who developed new onset nerve palsies; recovery was noted
in 80% of facial nerve, 62.5% of hypoglossal nerve, and 67% of sympathetic chain dysfunctions. Recovery
was not noted in trigeminal schwannomas. Good compensation was noted in 61.5% of vagal palsies(HOW
MUCH VAGUS RECOVERED). Fig 4 shows new onset nerve deficits and residual nerve deficits in the
follow up period. (IN FIG 4. OPTIC AND GLOSSOPHARYNGEAL were mentioned New onset long term
only)
Among the pre operativepreoperative nerve deficits, one case with hypoglossal weakness and one with
Two patients treated for trigeminal schwannoma showed recurrence along the skull base, who required
revision surgery and one of them underwent adjuvant radiotherapy. The other patient patient was not willing
A patient with a parapharyngeal schwannoma who passed the balloon occlusion test underwent trans oral -
trans cervical excision suffered cerebro-vascular accident and developed hemiplegia, and died of respiratory
We encountered an interesting case of a bilateral parapharyngeal schwannoma who underwent excision via
transcervical approach and endoscopic trans pterygoid - trans maxillary approach. Two years later, there was
development of left sided temporal lobe glioblastoma which required surgical intervention followed by
chemo radiation.
DISCUSSION
We analysed 10 year data retrospectively in our study comprising 97 patients. To the best of our knowledge,
this is one of the largest study comprising extra cranial non vestibular schwannomas. The mean age of the
patient was 37.4 years which is in accordance with the other studies(5 - 7) but we noticed there was a slight
male preponderance and occurs at a younger age group. Gender distribution was balanced. There was a
predilection to the left side in the males, while the laterality was balanced in females. The reason for this
laterality is not yet known but couldmight be related to some embryological process. Hybrid schwannoma-
neurofibroma were noted in 3 female patients that involved facial or vagal nerve(NEED TO HAVE A
and the rest in unusual locations like nose or maxillary sinus, tongue, supra glottis, anterior skull base,
brachial plexus, middle ear, orbit and sub occipital region. This pattern is consistent with other similar
studies(3, 8, 9).
The usual presentation is a mass lesion over the head and neck region including or bulge in the oropharynx,
which was noted in 68% in our study. Around 20% cases presented with pain over the lesion or in the
surrounding structures. The incidence of pain has been reported to be 3 - 15% according to various series(10,
11). The symptomatology can be varied and usually depends on the nerve affected and the pressure
symptoms caused by the tumour, such as voice change, dysphagia, ear fullness, vision loss, facial paresis,
tingling sensation or hypoaesthesia, loosening of teeth, proptosis, breathing difficulty or headache. In the
study by Wang et al, brachial plexus nerves were the most common nerve of origin, while it was the
Among the 10 patients with schwannoma arising from the extra temporal part of the facial nerve, 60% had
facial swelling, 20% presented with facial weakness, 10% had facial swelling and weakness and 10% were
We encountered single or multiple nerve dysfunction in 23.7% of the cases, the most common being vocal
cord paralysis, followed by hypoglossal nerve paresis. Almost all those with multiple palsies on presentation
were parapharyngeal schwannomas, while 2 arose in the orbit and the anterior skull base respectively.
Multiple nerve palsies are associated with extensive or large tumours. Since the involved nerve can render
permanent deficits, the knowledge of the nerve of origin aids in pre operative counselling of the patients and
expected outcomes(12).
Cross sectional imaging, particularly the MRI, was found to characterisecharacterize the lesion as a nerve
sheath tumour in almost 70% of the cases. It is therefore the preferred method of pre operative diagnosis in
the current times(8, 12). MRI can also help to identify the nerve of origin(3, 12). We found out that the
accuracy of FNAC to identify a schwannoma was 49.1% in our study, so it is not recommended as a
diagnostic modality for suspected schwannomas(1, 8, 9, 13). The yield of FNAC was often inadequate,
which is consistent with other studies(3, 9, 13). Furthermore, tumours in unusual locations may not be
amenable to aspiration cytology. FNAC may have a role in those cases where there is a suspicion of
malignancy or metastasis. Dongbin et al suggest core needle biopsy as a sensitive pre operative diagnostic
modality, but warn about the risks of nerve and organ damage, though there was no permanent nerve injury
in their study(13).
We used a variety of approaches given the wide variety of tumour locations, the most commonly employed
being transcervical approach with or without mandibular subluxation. Complete surgical excision remains
the standard treatment of choice(1, 3), preferably intracapsular enucleation whenever possible, to preserve
One important goal of our study was to analyse the short term and long term complications following the
surgery. The most common nerve related immediate complication was vagal palsy followed by facial
Analysis of cranial nerve function in the long run showed an interesting trend, especially vocal cord palsy, in
that due to contralateral compensation and return of nerve laryngeal function. in many cases caused only a
limited number of total long term deficits. In most of the cases with vagal dysfunction, Aaspiration and
dysphagia had considerably improved with only ~3% requiring long term nasogastric tube insertionfeed.
Such findings should encourage surgical intervention in such cases, Ssince a significant number of cases
present with nerve deficits, and complete surgical excision causes minimal morbidity in the long term,
almost a negligible risk of recurrence if complete resection has been performed. A considerable amount of
return of nerve related functions can be expected even if deficits occur post operatively. In contrast, pre
operative nerve deficits do not usually improve, which provides an impetus for early surgery before
Recurrence is rare following complete intra capsular excision (12, 15, 16). In our series, 2 cases recurred;
both had involvement of the skull base and arose from the trigeminal nerve and complete excision could not
be performed. This finding stresses the need for complete excision to avoid recurrences despite it being a
benign disease. It is therefore necessary to operate such cases when the tumour is not extensive, and so early
surgery, rather than wait and watch, should be advocated. Observational policy can be applied in patients
malignant peripheral nerve sheath tumour (MPNST) suggested that most of the MPNSTs develop
sporadically rather than transforming from benign tumours(17). Since there is evidence that most MPNSTs
are associated with neurofibromatosis type 1(18, 19); this might be the case with our only patent that
presented with bilateral parapharyngeal schwannomas who went on to develop glioblastoma in the temporal
lobe. It is likely that the patient had a syndromic association (Neurofibromatosis/ Schwannomatosis)(4) and
it is not known whether the malignancy arose de novo or was a transformation. Thus it is safe to conclude
Our study had some limitations, in that it was retrospective, and brachial plexus schwannomas were not
CONCLUSION
Extracranial head and neck schwannomas are rare, benign tumors with varied presentations. Surgery using
various approaches depending upon the tumour location is the mainstay of treatment as it carries minimal
morbidity and furthermore long term cranial nerve dysfunction is uncommon. Early surgery should be
advocated while the tumour is still small to prevent new nerve deficits and avoid recurrences. Recurrence is
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