Acoustic neuroma, also known as vestibular schwannoma (VS), is the most common tumor that occurs in a region between the brainstem and inner ear, called the cerebellopontine angle or CPA. This region contains the nerves of hearing, balance, and facial movement.
The symptoms of VS vary but the most common are hearing loss and tinnitus. Other possible symptoms are imbalance, taste disturbance, headache, facial weakness, and/or facial numbness. Some tumors do not cause any symptoms and are found incidentally. In our experience, a not insignificant number of patients will also describe cognitive difficulties such as slow-thinking, memory lapse, or a non-specific “brain fog”. These can be some of the most troubling symptoms affecting patients with VS, but unfortunately, less is known about them because these symptoms can be vague and are also common in the general population.
Fortunately, research into these cognitive symptoms is increasing. While the exact prevalence of detectable cognitive impairment in VS patients is still unknown, recent studies of patients with various cerebellar tumours have shown that most patients were found to have deficits in at least one area of cognitive functioning,*1,2 and a constellation of deficits (including cognitive and emotional symptoms) as part of a “cerebellar syndrome” has been described. Fortuitously, existing research suggests that most patients see improvement in cognitive function with surgery.*1,3 It should be noted that most of this research is not specific to VS, or even tumors in the CPA, but comes from research on cerebellar tumors in general. Thus, we should be judicious in applying it to patients with VS.
Cognitive symptoms can affect patients with untreated tumors or after treatment with surgery or radiation. Although the exact incidence of development of new symptoms after treatment is unknown, they may be common and transient after treatment. Occasionally, new or pre-treatment symptoms persist; in one study of patients who underwent surgery for VS, 7% of patients self- reported long-term difficulty concentrating in an open-ended questionnaire.*4
At the University of Cincinnati Medical Center, we have begun to utilize biofeedback therapy for patients with cognitive symptoms. We will publish our results in the near future. In summary, cognitive symptoms can be very troubling to patients with vestibular schwannoma but remain poorly understood compared to other symptoms. Most of our existing knowledge comes from research of other types of tumors that affect the cerebellum or CPA, which suggests cognitive symptoms may be more common than realized.
References
1. Bodranghien F, Bastian A, Casali C, et al. Consensus Paper: Revisiting the Symptoms and Signs of Cerebellar Syndrome. Cerebellum. 2016;15(3):369–391.
2. Goebel S, Mehdorn HM. A missing piece? Neuropsychiatric functioning in untreated patients with tumors within the cerebellopontine angle. J Neurooncol. 2018;140(1):145–153.
3. Manto M, Mariën P. Schmahmann’s syndrome—identification of the third cornerstone of clinical ataxiology. Cerebellum Ataxias. 2015;2:2.
4. Bateman N, Nikolopoulos TP, Robinson K, O'Donoghue GM. Impairments, disabilities, and handicaps after acoustic neuroma surgery. Clin Otolaryngol Allied Sc 2000;25(1):62–65.
This article which appeared in ANA NOTES June 2020 is reprinted with permission of the authors and our US sister organization, ANA.
Ravi N. Samy, MD, FACS; Mario Zuccarello, MD, FACS; Scott B. Shapiro, MD; Noga Lipschitz, MD; Allie Mains, FNP, CNRN; University of Cincinnati Medical Center