Treatment algorithm

Please note that formulations/routes and doses may differ between drug names and brands, drug formularies, or locations. Treatment recommendations are specific to patient groups: see disclaimer

ONGOING

small tumour (Koos grades 1-2)

1st line – observation

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small tumour (Koos grades 1-2)
1st line – 

observation

Small, asymptomatic tumours with normal cranial nerve function can be monitored by observation. Observation is also considered the first option in patients with small tumours with complete hearing loss.

Clinical observation is recommended if no growth appears on serial scans. At 6 months from presentation, patients who are being observed only should have an MRI, followed by yearly scans for several subsequent years, then scans every 2 years.[58]​ In select cases, patients with smaller growing tumours may still be observed if reliable follow-up can be assured.[57]

2nd line – focused radiation or surgery

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small tumour (Koos grades 1-2)
2nd line – 

focused radiation or surgery

Some patients with normal cranial nerve function may opt for focused radiation or surgery, but these treatments can deteriorate the nerve function and are usually not recommended.[13]

If tumour growth is apparent on serial scans, focused radiation or surgery is usually recommended. The choice depends on local physician expertise and patient preference.[73][74]

Surgery is completed with a number of approaches tailored to the patient's tumour size and degree of hearing loss, and to the surgeon's experience. In general, a middle fossa approach is completed through an incision that begins in front of the tragus of the affected ear and extends superiorly onto the temporal scalp. A 5 x 5 cm craniotomy is made above the ear, essentially centred on the ear canal. This approach is typically reserved for smaller tumours confined to the internal auditory canal when hearing preservation is attempted.[64]​ The translabyrinthine approach is performed through an incision behind the ear, working through the mastoid portion of the temporal bone, and does not preserve hearing because the inner ear is opened when, as the name suggests, the labyrinthine bone is drilled away. Thus, this approach is often used for patients who already have poor hearing or sometimes in cases where hearing preservation is unlikely, such as with large tumours.[64] The retrosigmoid approach is completed through an incision behind the ear allowing a craniotomy or craniectomy inferior to the transverse sinus and posterior to the sigmoid sinus.[64] This approach can be used for any sized tumour, with or without the intent of hearing preservation. Almost always, the posterior aspect of the internal auditory canal must be removed with a high-speed drill to access the component of the tumour extending into this area.[65][66][67]​ Intra-operative neurophysiological monitoring of cranial nerves, in particular the facial nerve, is considered standard of care. Monitoring of cranial nerves has changed the nature and success of surgery in terms of cranial nerve morbidity.[68][69][70][71]

Consider – salvage radiation or surgery

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small tumour (Koos grades 1-2)
Consider – 

salvage radiation or surgery

Additional treatment recommended for SOME patients in selected patient group

In approximately 5% to 10% of patients who opt for radiotherapy, tumours may grow despite treatment and may require salvage surgery.[72] Similarly, in patients selected for up-front surgical treatment, tumour recurrence may occur during follow-up, especially if less than a gross total resection is performed, and then may require follow-up salvage radiation. Generally speaking, if a person fails initial radiation treatment, then surgery is pursued. If a tumour recurs after surgery, then radiation is pursued.

Recurrence after microsurgical resection of small tumours is approximately 1% to 3% but may be slightly higher in cases of attempted hearing preservation.

medium tumour (Koos grades 3-4, tumour size <3 cm)

1st line – focused radiation or surgery

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medium tumour (Koos grades 3-4, tumour size <3 cm)
1st line – 

focused radiation or surgery

A majority of patients with medium-sized tumours may have vestibular/cochlear symptoms.[13]​ Up-front treatment with radiosurgery or microsurgery is typically recommended for such tumours, and long-term observation is usually not considered. The reason for this paradigm is that treatment outcomes are primarily driven by tumour size, and tumours >1.5 cm risk poorer outcomes if further growth occurs.[57]​ Stereotactic radiation carries lower risk than surgery. Nevertheless, surgery ensures complete resection of the tumour.[13]

Surgery is completed with a number of approaches tailored to the patient's tumour size and degree of hearing loss, and to the surgeon's experience. In general, a middle fossa approach is completed through an incision that begins in front of the tragus of the affected ear and extends superiorly onto the temporal scalp. A 5 x 5 cm craniotomy is made above the ear, essentially centred on the ear canal. This approach is typically reserved for smaller tumours confined to the internal auditory canal when hearing preservation is attempted.[64]​ The translabyrinthine approach is performed through an incision behind the ear, working through the mastoid portion of the temporal bone, and does not preserve hearing because the inner ear is opened when, as the name suggests, the labyrinthine bone is drilled away. Thus, this approach is often used for patients who already have poor hearing or sometimes in cases where hearing preservation is unlikely, such as with large tumours.[64] The retrosigmoid approach is completed through an incision behind the ear allowing a craniotomy or craniectomy inferior to the transverse sinus and posterior to the sigmoid sinus.[64] This approach can be used for any sized tumour, with or without the intent of hearing preservation. Almost always, the posterior aspect of the internal auditory canal must be removed with a high-speed drill to access the component of the tumour extending into this area.[65][66][67]​ Intra-operative neurophysiological monitoring of cranial nerves, in particular the facial nerve, is considered standard of care. Monitoring of cranial nerves has changed the nature and success of surgery in terms of cranial nerve morbidity.[68][69][70][71]

Consider – salvage radiation or surgery

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ONGOING
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medium tumour (Koos grades 3-4, tumour size <3 cm)
Consider – 

salvage radiation or surgery

Additional treatment recommended for SOME patients in selected patient group

In approximately 5% to 10% of patients who opt for radiotherapy, tumours may grow despite treatment and may require salvage surgery.[72] Similarly, in patients selected for up-front surgical treatment, tumour recurrence may occur during follow-up, especially if less than a gross total resection is performed, and then may require follow-up salvage radiation. Generally speaking, if a person fails initial radiation treatment, then surgery is pursued. If a tumour recurs after surgery, then radiation is pursued.

large tumour (Koos grade 4, tumour size >3 cm)

1st line – surgery

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large tumour (Koos grade 4, tumour size >3 cm)
1st line – 

surgery

With or without tumour growth on serial scans, surgery is recommended owing to the large size and potential damage to adjacent structures and resulting functional deficits. Surgery is recommended in most centres in preference to radiation, because of improvement in mass effect symptoms offered by surgery over radiation.[66][75]​​ Surgery to preserve hearing is not offered by most surgeons as the mass effect of such a large tumour has often already caused damage to hearing structures, although if the patient has useful hearing prior to surgery, a hearing preservation attempt is a reasonable undertaking, albeit not likely to succeed.​[53][67]​​ Surgery should focus on improving or maintaining quality of life and attempting to preserve the nerve function.[76]

Patients with large tumours may have modest brainstem compression and may present with facial nerve paresis and gait ataxia. Decompression of the brainstem and stretched cranial nerves is vital in such cases, and thus surgery is the preferred treatment option.

Surgery is completed with a number of approaches tailored to the patient's tumour size and degree of hearing loss, and to the surgeon's experience. In general, a middle fossa approach is completed through an incision that begins in front of the tragus of the affected ear and extends superiorly onto the temporal scalp. A 5 x 5 cm craniotomy is made above the ear, essentially centred on the ear canal. This approach is typically reserved for smaller tumours confined to the internal auditory canal when hearing preservation is attempted.[64]​ The translabyrinthine approach is performed through an incision behind the ear, working through the mastoid portion of the temporal bone, and does not preserve hearing because the inner ear is opened when, as the name suggests, the labyrinthine bone is drilled away. Thus, this approach is often used for patients who already have poor hearing or sometimes in cases where hearing preservation is unlikely, such as with large tumours.[64] The retrosigmoid approach is completed through an incision behind the ear allowing a craniotomy or craniectomy inferior to the transverse sinus and posterior to the sigmoid sinus.[64] This approach can be used for any sized tumour, with or without the intent of hearing preservation. Almost always, the posterior aspect of the internal auditory canal must be removed with a high-speed drill to access the component of the tumour extending into this area.[65][66][67]​ Intra-operative neurophysiological monitoring of cranial nerves, in particular the facial nerve, is considered standard of care. Monitoring of cranial nerves has changed the nature and success of surgery in terms of cranial nerve morbidity.[68][69][70][71]

Consider – radiation or observation

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ONGOING
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large tumour (Koos grade 4, tumour size >3 cm)
Consider – 

radiation or observation

Additional treatment recommended for SOME patients in selected patient group

As complete resection may lead to deterioration of cranial nerve function, incomplete resection of the tumour followed by radiation or observation is recommended.[13]

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Please note that formulations/routes and doses may differ between drug names and brands, drug formularies, or locations. Treatment recommendations are specific to patient groups. See disclaimer

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