Treatment of Manifestations
Pain management. Various pain medications (e.g., calcium channel alpha 2 delta ligands such as gabapentin, tricyclic antidepressants such as amitriptyline, serotonin-norepinephrine reuptake inhibitors such as venlafaxine) may be helpful individually or as adjuncts. No class of pain medication appears to be better than another [Author, personal communication]. A comprehensive, multimodal approach to pain management guided by a pain management specialist or neurologist provides an opportunity for long-term management of symptoms without surgical intervention.
Emotional health. Pain management may improve anxiety and depression. Referral to mental health professionals may also be warranted.
Surgical management of peripheral nerve tumors. Surgery is indicated for symptomatic schwannomas (e.g., uncontrolled localized pain related to a schwannoma, schwannoma resulting in a neurologic deficit). The principles for surgical resection of peripheral nerve tumors are similar to those utilized for resection of sporadic nerve sheath tumors:
The potential benefits of surgery must be weighed carefully against the potential risks.
Given the technical challenges involved in surgery, referral to an expert center with a peripheral nerve surgeon is recommended.
It is important that surgery be performed in conjunction with ongoing pharmacologic pain management, as pain relief following tumor resection is not ensured.
Management of spinal and cranial nerve tumors. Performing surgery for each newly identified tumor is impractical and inadvisable. Therefore, delineation of "presymptomatic" tumors at initial evaluation (and each subsequent evaluation) is requisite to establishing a paradigm of expectant management for longitudinal observation. Affected individuals should be educated on the most common, early symptoms that suggest that an existing tumor is becoming problematic. Early identification and intervention for problematic tumors improves outcomes for many central nervous system tumors. Intraspinal schwannomas >5 mm in size warrant longitudinal imaging and clinical surveillance. Growing intraspinal schwannomas may cause significant impact to adjacent neural structures, and surgical removal at the time of early onset of symptoms remains the mainstay of treatment. This approach balances the need to maximize functional outcome and to avoid unnecessary prophylactic surgical intervention.
When considering surgical intervention for a cerebellopontine angle cranial nerve schwannoma it is important to consider historical cues, physical exam findings, and imaging observations that may help delineate a facial nerve etiology. Because hearing preservation and facial nerve preservation are significant considerations when making a decision to intervene on schwannomas of the internal auditory canal, these become critical in determining the timing of intervention. In general hearing preservation rates are dramatically reduced when vestibular schwannomas exceed 1 cm in size, and facial nerve function significantly declines when schwannomas exceed 2.5-3 cm. It remains unclear how best to translate the success seen with radiosurgery for sporadic vestibular schwannoma management to those with schwannomatosis [Kondziolka et al 1998].
Management of meningiomas. There is a paucity of outcome data from surgical, radiosurgical, and radiation therapy for meningiomas in individuals with schwannomatosis. Therefore, management recommendations in individuals with schwannomatosis and meningioma are the same as for those with sporadic meningioma.
Radiation therapy. There is a theoretic risk that radiation exposure can increase the risk for malignant transformation; however, this has not yet been demonstrated in individuals with schwannomatosis [Evans et al 2006]. The exact role of this modality needs to be established.
Surveillance
Based on the 2016 American Association for Cancer Research Childhood Cancer Predisposition Workshop, surveillance guidelines have been proposed [Evans et al 2017].
SMARCB1-related schwannomatosis
Baseline MRI examination of the brain and spine at diagnosis, then every two to three years beginning at age ten years
Consideration of whole-body MRI examination and increasing surveillance frequency if symptomatic
LZTR1-related schwannomatosis [Plotkin et al 2012, Merker et al 2014, Evans et al 2017]
Baseline MRI examination of the brain and spine at diagnosis, then every two to three beginning at age 15 to 19 years
Consideration of whole-body MRI examination and increasing surveillance frequency if symptomatic
High cost and poor insurance reimbursement limit the wider use of whole-body MRI.