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Patient presents with recent-onset facial muscle spasms
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An 85-year-old white female was referred to our clinic by her optometrist for evaluation of recent-onset facial muscle spasms. The patient reported periodic closing of her right eye with concurrent elevation of the right side of her mouth. These spasms began 3 months prior and occurred one to five times per day. She also reported feeling that her right ear was full of water once every 2 to 3 weeks.
The patient’s past ocular history was unremarkable for any eye diseases. Ocular surgical history was significant for cataract removal from both eyes and pterygium removal from the left eye. There was no significant family ocular history.
Her medical history was significant for hyperlipidemia, angina, cardiac arrhythmia, actinic keratosis, sensorineural hearing loss, vertigo and other vestibular troubles. Current medications included mometasone furoate 0.1% cream, a calcium/vitamin D supplement and aspirin (81 mg). The patient reported an allergy to penicillin.
Corrected distance visual acuities were 20/25-1 OD and 20/25+2 OS. Her pupils were equal, round and reactive to light with no relative afferent pupillary defect. Extraocular motilities were full with no restrictions. Cover test revealed orthophoria at distance and low exophoria at near. Confrontation visual fields were full to finger count in both eyes. Intraocular pressures by applanation tonometry were 15 mm Hg OD and 18 mm Hg OS. No facial muscle spasms were visualized during the exam.
The exam notes from the patient’s comprehensive eye examination by the referring optometrist 2 weeks earlier indicated uncorrected distance visual acuities of 20/40-1 OD and 20/40 OS. All entrance testing was consistent with the results found at our exam. Best corrected visual acuities were 20/25-1 OD and 20/25 OS with a manifest refraction of +0.50-1.50 x 040 OD and +0.50-1.50 x 085 OS.
Slit lamp examination of the anterior segment at the comprehensive exam was unremarkable except for pseudophakia in both eyes and mild nasal corneal scarring from pterygium removal in the left eye. Dilated fundus examination of the posterior segment revealed healthy optic nerves with 0.2 round cup-to-disc ratios in both eyes. The maculae were flat with hard drusen, and the retinal periphery was flat and intact 360 degrees in both eyes.
Images: Dailey K
A comprehensive examination was not completed at our encounter with the patient because she had recently had one and was referred specifically for evaluation of her facial muscle spasms. Based upon the history gathered and the lack of ocular pathology reported by the referring optometrist we suspected that there was intracranial pathology affecting cranial nerves seven and eight. Because of this, it was decided that neuroimaging would have the greatest diagnostic value, and further ocular and visual assessment such as fundus photos and automated perimetry could be completed at a later time if needed.
Magnetic resonance imaging (MRI) of the brain with and without gadolinium contrast was ordered and performed 9 days later. The MRI revealed a 4 x 9 mm circumscribed, homogenously enhancing mass at the right internal auditory canal that extended slightly into the right cerebral pontine angle. The mass appeared to spare the lateral aspect of the internal auditory canal and fill the remainder of the canal, resulting in displacement and impingement of the seventh and eighth cranial nerves.
For eye care providers, the important differential diagnoses to consider in patients with facial muscle spasms are benign essential blepharospasm (BEB) and hemifacial spasm.
Both of these diagnoses are characterized by involuntary, rapid facial muscle contractions, but the etiology and distribution of muscle contraction varies between them. A thorough history and observation are generally the only information required for diagnosis.
Benign essential blepharospasm
BEB is characterized by bilateral contractions of the orbicularis oculi, procerus and corrugator. It is an idiopathic condition thought to result from a dysfunction in the blinking reflex control center. If accompanied by intermittent contraction of the orofacial muscles, it is known as Meige syndrome. Patients are generally 50 to 70 years old and complain of increased blinking lasting seconds to minutes. Severe spontaneous eyelid closure can result in functional blindness and disability.
Treatment for BEB includes botulinum toxin, distraction techniques, treatment of any underlying ocular surface disease, medications and surgery in severe cases. Many different medications have been used to treat BEB, but most are only occasionally effective in relieving symptoms. These include muscle relaxants such as baclofen, benzodiazepines such as clonazepam, antipsychotics such as haloperidol, anticholinergic agents such as trihexyphenidyl and dopamine depleting drugs such as tetrabenazine.
Botulinum toxin injections are the most effective nonsurgical treatment for BEB. The muscle paralysis caused by botulinum toxin injection is not permanent, and the injections must be repeated every 3 to 6 months. Because botulinum toxin injections are less invasive than surgery, they are usually the first line treatment in BEB.
The main surgical approach used to treat BEB is a protractor myectomy. This involves removal of some or all of the eye muscles responsible for eyelid closure through an incision in the upper eyelid. Ideally, only the upper portion of the orbicularis must be removed, but portions of the lower orbicularis, corrugator and procerus can be removed as well. Protractor myectomy is a technically difficult procedure and is often more effective after botulinum toxin treatment of the muscles.
Hemifacial spasm
Hemifacial spasm is characterized by unilateral, intermittent, synchronous contraction of the orbicularis oculi and other facial muscles. The muscular contractions experienced by patients with hemifacial spasm are secondary to compression or irritation of the facial cranial nerve (CN VII). Many cases of hemifacial spasm are idiopathic or caused by benign conditions such as Bell’s palsy or compression of the nerve from otherwise normal arteries. However, there are also a multitude of more nefarious causes including aneurysm, multiple sclerosis, arteriovenous malformation or tumor near the brainstem or cerebellopontine angle. Patients are generally 30 to 60 years old and more commonly female.
After brain pathology has been ruled out as a potential cause of the muscle spasms, medications, botulinum toxin, distraction techniques and surgery are all potential treatment options. The classes of oral medications used to relieve hemifacial spasm are identical to those discussed above. As with BEB, oral medications only occasionally relieve symptoms. Botulinum toxin injections are generally the first-line treatment modality for this condition and are highly effective.
Surgical treatment for hemifacial spasm involves microvascular decompression of the facial nerve, known as the Janetta procedure. The procedure necessitates removal of part of the skull just posterior to the ear in order to directly visualize the nerves and vasculature. Although highly effective, the invasive nature of the surgery precludes it from being used in all cases except those refractory to all other treatments.
While the presentation, patient symptoms and treatment can be similar for both of these conditions, proper diagnosis is critical for making appropriate management decisions. Most important is keeping in mind the different etiologies of these conditions. Hemifacial spasm is a disorder of a cranial nerve making an underlying structural cause more likely than with BEB. For this reason, any time the diagnosis of hemifacial spasm is made, an MRI must be done to rule out brain pathology.
This patient’s diagnosis
Our patient was diagnosed with hemifacial spasm secondary to a vestibular schwannoma.
Vestibular schwannomas, also called acoustic neuromas, are benign, slow-growing tumors that arise from the myelin sheath cells of the vestibular branch of CN VIII. These tumors are relatively common, accounting for approximately 8% of all intracranial tumors and 80% of cerebellopontine angle tumors. There are a reported 2,000 to 3,000 new cases per year. Mean age at diagnosis is 53 years old, and males and females are equally affected. Eighty-five percent of these tumors are reported to occur in Caucasians.
The most common presenting symptoms of vestibular schwannomas are gradual unilateral hearing loss, unilateral tinnitus, unsteadiness/loss of balance, vertigo and facial numbness or weakness. Hemifacial spasm, such as that seen in our patient, is a less common presenting symptom, reported in only 10% of cases.
In the case of our patient, compression of CN VII, and the resulting hemifacial spasm, was caused by the tumor of CN VIII. CN VII and CN VIII share a close anatomic relationship, as they travel intracranially. The majority of CN VII fibers originate in the facial nerve nucleus in the pons while CN VIII fibers originate at the border of the pons and medulla. After exiting their respective portions of the brainstem, CN VII travels medially to CN VIII through the cerebellopontine angle. The nerves then enter the internal acoustic meatus, a bony canal in the petrous portion of the temporal bone, on their way to the inner ear.
Vestibular schwannomas often originate in the internal acoustic meatus and compress the auditory/cochlear branch of CN VIII. This results in the prominent early symptoms of unilateral hearing loss and tinnitus. As the tumor enlarges, it spreads intracranially into the cerebellopontine angle. The tumor can damage CN VII either within the internal acoustic meatus or in the cerebellopontine angle because they are in close proximity in both locations. Once the tumor has spread intracranially it may also cause compression of the brainstem and involvement of other cranial nerves, especially the trigeminal nerve (CN V).
Initial diagnosis of a vestibular schwannoma typically occurs after MRI in a patient with unilateral hearing loss. Many tumors discovered in the cerebellopontine angle are assumed to be schwannomas because of their propensity to form there. However, multiple types of tumors can be found in this area, and diagnosis of a vestibular schwannoma cannot rely on MRI alone. Suspicion of the diagnosis may be based upon certain anatomical features on MRI, such as absence of the dural tail sign commonly seen with meningiomas; but final diagnosis always requires biopsy of the tissue.
Our patient’s presenting symptoms of facial muscle spasms and past medical history of vertigo and unilateral hearing loss can all be explained by the presence of a vestibular schwannoma. Involvement of CN VII accounts for the facial muscle spasms, while involvement of CN VIII accounts for the vertigo, feeling of water in the ear and potentially the sensorineural hearing loss diagnosed years before.
When symptoms can be localized to multiple cranial nerves, always rule out intracranial pathology. Understanding the pathways of cranial nerves and brainstem anatomy allows for correlation of patient symptoms and localization of potential pathology. Not only is this important for preventing a tumor from going undiagnosed, but it can also help direct radiologic studies to the appropriate area of the brain.
Treatment
Schwannomas are typically classified into one of three categories based upon extent of the tumor on MRI: entirely intracanalicular, intracranial extension without brainstem distortion or intracranial extension with brainstem distortion. Other diagnostic tests such as audiograms and brainstem audio evoked responses (BAER) are used to evaluate the possibility of saving hearing. These tests, along with the MRI classification of the tumor, are the main determinants of the primary treatment modalities. Watchful waiting is an option for some patients, as vestibular schwannomas are benign and slow growing. However, if treatment is desired or indicated, the two options are surgery or radiation.
Approximately 60% of patients diagnosed with vestibular schwannomas are treated with surgery. There are many surgical approaches that can be taken depending on the location and size of the tumor. Surgery is more likely to be done if useful hearing is still present. In addition, tumors that are classified as intracranial with brainstem distortion will generally be removed to prevent permanent damage.
Complete schwannoma removal is possible in 95% of cases, and mortality is less than 1%. Permanent facial paralysis secondary to CN VII damage is the largest source of disability after tumor removal.
Radiation is the treatment of choice in a reported 20% of cases. Traditional radiation therapy has not proven to be very effective, so stereotactic radiation is more commonly performed. Stereotactic radiation involves a single dose of radiation delivered in the exact size and shape of the tumor. This varies from traditional radiation, where many doses of radiation are delivered over an extended period of time.
Radiation does not cure the tumor but rather slows or stops its growth. Because of this, patients who undergo radiation for treatment of their tumor will require indefinite MRIs for monitoring. The greatest side effect of radiation therapy is damage to healthy tissues surrounding the tumor.
Patient management
We referred our patient to an ear, nose and throat (ENT) specialist to determine the best course of management. Audiometry testing by the specialist revealed sensorineural hearing loss in both ears. The extent of hearing loss in the left ear was consistent with levels measured in 2011; but the loss in the right ear had progressed, particularly at lower frequencies.
Due to the benign nature of vestibular schwannomas and the patient’s age, the ENT specialist recommended not treating the tumor at this time. Although the patient’s asymmetric hearing loss, balance difficulties and hemifacial spasm are likely caused by the tumor, it was noted that surgical or radiation treatment could result in further damage to CNs VII and VIII, causing symptoms to worsen. The specialist recommended that the patient be re-evaluated in 6 months by audiogram and MRI. If growth of the tumor is documented, stereotactic radiation will be considered. Surgery was ruled out as an option due to the patient’s age.
Botulinum toxin injections were offered to treat the patient’s hemifacial spasm. The patient decided to delay the injections until the tumor is re-evaluated in 6 months. She stated that the spasms are not debilitating, and she has concerns about the injections needing to be repeated every few months. If the tumor has not grown in size and no treatment is going to be pursued in 6 months, botulinum toxin injections will then be initiated. The patient was educated that injections could be started sooner if the muscle spasms become more troublesome.
- References:
- Biousse V, Newman N. Disorders of the Eyelids. In: Biousse V, Newman N, eds. Neuro-ophthalmology Illustrated. 1st ed. Thieme; 2009:498-500.
- Carter B, et al. Acoustic Neuroma. UC San Diego Health System Neurosurgery website. http://neurosurgery.ucsd.edu/acoustic-neuroma/. Updated December 2013. Accessed September 17, 2015.
- Clinical Practice Advisory Group of the British Association of Otorhinolaryngologists-Head and Neck Surgeons. Clinical Effectiveness Guidelines. Acoustic neuroma (Vestibular schwannoma). https://entuk.org/sites/default/files/files/3412_Acoustic_Neuroma.pdf. Published Spring 2002. Accessed September 17, 2015.
- Gal TJ, et al. Otolaryngol Head Neck Surg. 2010;doi:10.1016/j.otohns.2010.01.037.
- Hain T. Acoustic Neuroma. American Hearing Research Foundation website. http://american-hearing.org/disorders/acoustic-neuroma/. Updated October 2012. Accessed September 17, 2015.
- Hallet M. Benign Essential Blepharospasm. National Organization of Rare Disorders website. https://rarediseases.org/rare-diseases/benign-essential-blepharospasm/. Updated July 2013. Accessed September 17, 2015.
- Skorin L. Blepharospasm and Hemifacial Spasm. In: Onofrey B, Skorin L, Holdeman N, eds. Ocular Therapeutics Handbook: A Clinical Manual. 3rd ed. Lippincott Williams & Wilkins; 2011:574-575.
- Sampath P, et al. J Neurosurg. 1997;doi:10.3171/jns.1997.87.1.0060.
- For more information:
- Kathryn Dailey, BS, is a fourth year optometry intern at the Pacific University College of Optometry in Forest Grove, Ore. She can be reached at: khdailey@pacificu.edu.
- Leonid Skorin Jr., OD, DO, MS, FAAO, FAOCO, can be reached at the Mayo Clinic Health System in Albert Lea, Minn.; skorin.leonid@mayo.edu.
Disclosures: Dailey and Skorin report no relevant financial disclosures.