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A week in neuro-ophthalmology, where the rare is routine

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Steven Turpin BS
Pacific University College of Optometry

Dr Leonid Skorin Jr
OD DO MS FAAO FAOCO
Mayo Clinic Health System, Albert Lea, MN, USA

 

Perspectives for the optometrist

 

Our patients might come to us with no specific complaints, or they may walk in reporting complete, sudden vision loss. Usually it’s somewhere in between but it’s up to us to determine how urgent the problem is.

A quick way to become more comfortable with making decisions regarding vision-threatening situations is to spend time with those at the end of the referral line. For them, the rare is routine and managing seemingly complex and serious issues is the norm.

We hope that sharing some of the cases we see during a typical week in our neuro-ophthalmology clinic can help as a refresher for primary care clinicians who are often faced with making initial treatment or referral decisions. We will provide a brief overview of relevant case information, current facts about each condition and finally, a description of how that information was used to manage the patients.

MONDAY: TEMPORAL ARTERITIS

The case

A 62-year-old white male was referred to the neuro-ophthalmology clinic by his comanaging optometrist for evaluation. The patient reported that he had experienced severe vision loss in the right eye on waking about five weeks previously. He said that ‘99 per cent of the vision was gone in his right eye.’ He denied any headaches, jaw claudication or scalp tenderness associated with the vision loss. His medical history was positive for suspected temporal arteritis (TA) eight years earlier; however, he had not experienced any vision changes at that time. He was also an insulin-dependent diabetic patient.

217 OL Figure 1
Figure 1. Fundus photo of the swollen optic disc in the right eye


During our evaluation, best corrected vision in his right eye was light perception and 6/7.5 in his left eye. He had a marked relative afferent pupillary defect and severe swelling of the optic disc in the right eye (Figure 1). The optic disc of the left eye was unremarkable. Laboratory testing revealed an elevated C-reactive protein (CRP) level of 4.7 mg/L, an elevated erythrocyte sedimentation rate (ESR) of 102 mm/hr and a platelet count of 145,000 mm3. We performed a temporal artery biopsy on the patient’s right side three days after the consultation. A 1.3 mm specimen was excised and processed by the pathology laboratory (Figure 2). The results came back negative for inflammation that would indicate TA.

217 OL Figure 2
Figure 2. Isolated temporal artery specimen prior to excision. Arrow indicates vessel.

 

The facts

Temporal arteritis, also known as giant cell arteritis, is a chronic autoimmune disorder characterised by inflammation of the small- and medium-sized arteries throughout the body. Unilateral vision loss is a common presenting symptom of TA due to arteritic anterior ischaemic optic neuropathy (AAION). Inflammation and hyperplasia of the intimal layers of the arteries causes occlusion of the short posterior ciliary arteries. This occlusion causes the optic disc to become ischaemic in patients with AAION, leading to vision loss. Patients with TA may also experience severe headaches, scalp tenderness, jaw claudication and general malaise. The peak age of incidence is between 60 and 75 years and it occurs very rarely under the age of 50 years. A patient presenting with vision loss and two or more of the other characteristics is highly suspect for temporal arteritis with AAION.

Differentiating AAION from NAION

The primary differential for AAION is non-arteritic anterior ischaemic optic neuropathy (NAION). Unilateral vision loss in NAION is, on average, less severe (6/30 or better) than is seen with AAION. Patients with NAION are often younger (< 60 years of age) and do not complain of headaches or other associated symptoms. Objectively, the optic disc of the affected eye appears less swollen in NAION compared to AAION. Additionally, the disc of the non-affected eye in a patient with NAION may be classified as a ‘disc at risk’ characterised as a cup/disc ratio less than 0.3. AAION is not associated with any specific cup/disc ratio measurements. While NAION has no standard treatment and often resolves on its own, AAION associated with TA is much more serious and may result in severe vision loss in the fellow eye within a week if treatment is not initiated quickly. The risk of bilateral blindness makes differentiation of the two diseases critical.

The most reliable differentiating tests are the erythrocyte sedimentation rate (ESR) test, C-reactive protein (CEP) test and complete blood count (specifically, platelet count). CRP values over 2.5 mg/L, ESR values over 50 mm/hr and a platelet count of greater than 400,000 mm3 are all indicative of TA/AAION.1 Laboratory tests for NAION generally come back normal. If a patient’s laboratory results are elevated, the next step is to perform a temporal artery biopsy, which is the gold standard for TA diagnosis. A greater than or equal to 1.0 cm specimen is excised from the frontal branch of the superficial temporal artery and submitted to a pathology laboratory for evaluation. Positive tests are characterised by the presence of near complete lumen occlusion, ‘giant’ multi-nucleated cells and granulomatous inflammation. A negative specimen will not exhibit any of these characteristics.

Corticosteroids are the treatment of choice in those with TA.1 Treatment should be initiated immediately if TA is suspected, even if a temporal artery biopsy has not been performed. Treatment will not skew the results of the biopsy until two to four weeks after treatment has been initiated.2,3

The best treatment for those patients with severe vision loss in one eye is one gram of intravenous methylprednisone for three days followed by oral steroids (1 mg/kg of body weight/day).4 If this option is not available, 40 to 100 mg of oral prednisone (about 1 mg/kg of body weight/day) should be started and increased (maximum of 100 mg/day) until symptomatic improvement is reached.5 ESR and CRP should be checked weekly to measure improvement. Once an effective dose is reached, it should be continued for four to six weeks. The steroid should then be tapered very slowly, reducing the dosage by 5-10 mg per month. As a result, treatment regimens can last from one to two years.

Putting it all together 

Our case is a good example of the ambiguity associated with suspected temporal arteritis. Our patient exhibited severe vision loss but no other symptoms. His ESR and CRP were elevated, but the results may have been complicated due to concurrent end-stage renal disease from his long-standing diabetes which may also increase inflammatory markers.6 His history was positive for suspected TA in the past; however, a temporal artery biopsy was never performed. When the procedure was performed, the results were negative. In the end, half the diagnostic data pointed toward TA, while the other half was not consistent with the typical disease characteristics.

Ultimately, he was treated with oral steroids. Although he did not present to his optometrist until two weeks after he had first noticed his vision loss, he was immediately started on 60 mg of oral prednisone daily. Two weeks later, the medication was stopped by his general practitioner due to a rapid elevation in his blood glucose levels (245 mg/dL). It was not until after treatment was discontinued that he was referred to our office.

The patient reported that his vision had improved when the therapy was initiated, but deteriorated rapidly when it was stopped. We cannot definitely say the discontinuation of the treatment caused further vision impairment because vision loss can continue in up to 13 per cent of patients receiving standard treatment.7 Fortunately, his left eye was not affected at the time, though it is at risk. The temporal artery biopsy was performed about five weeks after the onset of symptoms as well as after the steroid treatment. Only 60 per cent of biopsies come back positive under these circumstances.2 The recommendation was made to perform the procedure on the other side as 23 per cent of bilateral temporal artery biopsies are positive on one side and negative on the other. Results of the second biopsy were negative as well. We classified his condition as NAION. Regardless of the diagnosis and despite all of the interventions, the patient’s vision in his right eye is not likely to improve.

We believe our case exemplifies the seriousness of this condition and the potentially detrimental effects of delayed treatment and testing. Patients who are at most at risk should be educated about returning to the clinic immediately if they experience any of the symptoms described above. Additionally, communication between practitioners is paramount to preventing vision loss through early treatment and laboratory testing. Treatment protocol should be well understood by all parties to prevent relapse and further complications.

 

TUESDAY: PSEUDOTUMOUR CEREBRI

 

The case

A 24-year-old white female was referred to the neuro-ophthalmology clinic by the emergency department for evaluation. The patient reported ‘spots in her vision’, primarily her left eye, which had started five days before presenting to the emergency department. She was experiencing severe headaches across the frontal portion of her head and they were progressively getting worse. Her medical history was positive for pseudotumour cerebri two years prior. The patient had also been taking oral tetracycline medication to treat her acne.

During our evaluation, her corrected visual acuities were 6/9 in each eye. She subjectively reported ‘grey spots’ both superior temporally and superior nasally during Amsler grid testing of the left eye. Amsler grid testing was unremarkable for the right eye. Visual field testing was performed for each eye (Figure 3). Enlargement of the blind spot was noted in the right eye and a superior arcuate defect extending from an enlarged blind spot to the nasal field, crossing the horizontal midline was noted in the left eye. Both optic discs were elevated and indistinct, consistent with papilloedema. Other findings during the dilated fundus examination were unremarkable. The patient returned to the emergency department and a lumber puncture was performed. Opening pressure was measured to be 34 cm.

217 OL Figure 3
Figure 3. 24-2 Humphrey visual field of the right and left eye in a patient with pseudotumour cerebri

 

The facts

Pseudotumour cerebri is also known as idiopathic intracranial hypertension (IIH). It is characterised by increased intracranial pressure due to an unknown cause. Vision disturbance or obscuration is generally transient and visual acuity is not drastically reduced as the macula is not usually involved.8 The most common area of visual field loss in patients with IIH is inferonasal.9 Associated symptoms include severe headache with or without nausea and pulsate tinnitus (pulse-synchronous whooshing sound in ears). The condition is most commonly seen in overweight women of child-bearing age. Medications that are commonly used by this population may increase the risk of developing IIH including oral contraceptives and oral tetracyclines.

A patient with these signs and symptoms should be referred, specifically for neuro-imaging. IIH is a diagnosis of exclusion and magnetic resonance imaging is indicated to rule out an increase in intracranial pressure due to a mass or hydrocephalus and a magnetic resonance venography should be done to rule out dural sinus thrombosis. A lumbar puncture is then performed to measure the intracranial pressure. Normal opening pressure is between 10 and 20 cm. A reading over 25 cm is considered diagnostic for IIH provided imaging is negative for any other pathology.

In addition to being a diagnostic test, lumbar puncture usually provides some immediate, short-term relief of symptoms to patients with severe headaches. Long-term treatment includes weight loss and medications to reduce intracranial pressure. A six per cent reduction in body weight has been shown to improve signs and symptoms indefinitely if the weight is maintained.10 In cases where weight loss is not enough, oral carbonic anhydrase inhibitors (CAI) are indicated.

Oral acetazolamide (Diamox) is the first-line medical treatment for IIH and acts by reducing the production of cerebral spinal fluid. Alternatively, topiramate (Topamax) which is a weak CAI and aids in weight loss may also be a good option for some patients. In cases of more severe visual field loss, a surgical shunt to drain the cerebral sinus fluid or optic nerve sheath fenestration may be appropriate.

A surgical referral should be made if a new visual field defect is noted or a previously noted defect gets worse even with medical treatment.

Putting it all together

Our patient’s magnetic resonance imaging and magnetic resonance venography scans were negative for any pathology when she was initially diagnosed with IIH two years prior to the referral. At that time, she had been prescribed two, 500 mg Diamox tablets daily and reported improvement of symptoms. She continued to take her medication for over 18 months but stopped because she felt her symptoms had completely resolved. Over the next four months, her symptoms returned. She restarted the Diamox; however, it did not provide headache relief and prompted her to present to the emergency department.

Computed tomography (CT) of the brain was done in the emergency department the day of our consultation and was found to be negative for a mass. The patient reported relief after a lumbar puncture was performed and was started back on the same Diamox dosing. Additionally, 25 mg of topiramate daily by mouth was prescribed to aid in weight loss and reduce intracranial pressure. She was scheduled for a follow-up visual field test in one month.

This case is more straightforward than the last but it illustrates an important point. Making the appropriate referral is crucial even if the answers seem obvious. Findings were consistent with a previous diagnosis and it may have been tempting to observe the patient to see if restarting the Diamox medication would eventually alleviate her symptoms. However, the referral served two important purposes: any serious pathology was ruled out with CT scanning and the lumbar puncture provided instant relief for the patient’s headache symptoms.

 

THURSDAY: BELL’S PALSY

 

The case

A 72-year-old white male was referred for consultation by his ophthalmologist to the neuro-ophthalmology clinic with complaints that the right side of his face and mouth were ‘droopy’ and that he was unable to close his right eye. After further questioning, the patient reported the onset was sudden and painless; however, he did not know when the problem had started. The patient’s wife had first noticed the problem 10 days previously.

During our evaluation, entering corrected acuities were 6/30 in the right eye and 6/7.5 in the left eye with no improvement on pinhole. The anterior segment examination revealed mild, diffuse injection of the bulbar conjunctiva and areas of superficial punctate keratitis covering the entire cornea of the right eye. During auxiliary cranial nerve testing, the patient was unable to wrinkle the right side of his forehead or smile with the right side of his mouth. There was blunting of the nasolacrimal fold on the right side compared to the left side. Examination of the right ear canal for herpetic lesions to rule out herpes zoster oticus (Ramsay-Hunt syndrome) was unremarkable. When asked to close his eyes, the right eye remained open and did not properly elevate while the left closed normally (Figure 4).

217 OL Figure 4
Figure 4. Lack of Bell’s phenomenon in a patient with Bell’s palsy attempting to close both eyes


We rated his Bell’s phenomenon (elevation of the eyes when the lids are closed) as poor. Tear break up time was four seconds in both eyes and the Schirmer-2 test was 8 mm in the right eye and 6 mm in the left. Corneal sensitivity was tested with a cotton swab and rated as very poor.

The facts

Bell’s palsy is characterised by hemi-facial paresis and inhibited eyelid closure. The pathophysiology of Bell’s palsy involves inflammation of cranial nerve seven (CN VII). Infection of the nerve ganglion by the herpes simplex virus (HSV-1) in the most commonly accepted cause of the condition. Vision may be affected due to ocular surface decompensation as a result of blink inhibition. The lack of consistent blinking also causes tearing, burning or general ocular irritation.

Vision-care providers should be familiar with eye and facial signs that may aid in differentiating between stroke and Bell’s palsy. Specifically, it is not likely that eyelid closure and frontalis function (furrowing of the forehead) would be affected in a patient who suffered a stroke; however, they may exhibit other neurological signs. Conversely, patients with Bell’s palsy will have a complete unilateral facial palsy but no other signs. If a stroke is suspected, patients require immediate referral so that patients who require anti-clotting treatment can be treated in a timely manner. Prognosis is most favourable if treatment is started within the first three hours after onset of a stroke.

Bell’s palsy is significantly more benign and the treatment window is much broader. The discoveries of the inflammatory and viral nature of the condition led to treatment strategies combining both corticosteroids and antivirals. Administration of oral steroids within 72 hours of onset has been shown to significantly increase the rate of recovery.11 

Putting it all together

We presented the information to our patient and his wife, explaining that because the onset had been 10 days prior, treatment might not be as effective as if it had been provided sooner. The patient and his wife elected to do combination therapy. We prescribed oral acyclovir 400 mg twice-daily and oral prednisone 10 mg twice-daily, both for one week.

We then explained treatment options to heal the ocular surface. Patients who develop corneal damage despite appropriate conservative therapy need surgery to reanimate their paralysed eyelids. The most vulnerable patient is one who manifests the ‘BAD’ syndrome, that is, lacks the Bell’s phenomenon, and has corneal anaesthesia and dry eye.12 The patient was completely unable to close his eye and did not blink once during the examination. His Bell’s phenomenon was reduced when he attempted to close his eyes. Our testing also confirmed that he had corneal anaesthesia and dry eye, putting him at high risk for corneal damage.

We chose to apply 3M surgical tape horizontally from the medial to lateral aspect of the upper lid to act as a temporary weight. This was enough to induce a partial ptosis in primary gaze and close the eye when the patient tried to shut his eyes and the levator relaxed. Gel drop artificial tears were prescribed every two hours and preservative-free ointment was prescribed for overnight coverage.

After two weeks, his condition had greatly improved. He and his wife reported that he had completed the oral antiviral and steroid treatment as directed. The visual acuity in his right eye improved to 20/25+ and he had no other visual complaints. His corneal epithelium was intact and did not stain with sodium fluorescein. He was able to shut both his eyes tightly and did not display any residual lagophthalmos. A referral may be appropriate if full function of the orbicularis oculi muscle does not return and the cornea remains exposed. Lid weights can be surgically implanted into the upper eyelid to induce ptosis and protect the ocular surface.

Conclusion

The question of when to refer, to whom and how quickly can be tricky. Often, it depends on the comfort of the primary care clinician in making a diagnosis and initiating treatment. Regardless of the ultimate decision, precise documentation of all examination information is crucial. It allows optometrists to track improvement if they are managing the patient and it also allows the physicians receiving a referral to cross-check information and make sure they have the facts straight. A thorough initial examination, accurate assessment and differential diagnosis and good communication between practitioners are the keys to success and may save a patient’s vision in an urgent or emergent situation.

Disclosures

Turpin and Skorin report no relevant financial disclosures.  

 

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