Ophthalmology

February 2014

Neuro-ophthalmology Question of the Week: Blepharospasm Treatment

http://microbiology2009.wikispaces.com/Botulism

Question:

Which of the items below are appropriate for the treatment of benign essential blepharospasm?

1. Botox injections

2. Assessment of antibodies to Botox

3. Facial neurectomy

4. Orbicularis myectomy

__________________________________________________

Correct Answers:

1. Botox injections

4. Orbicularis myectomy


References:

1. Myectomy for blepharospasm 2013. Pariseau, Brett; Worley, Michael W.; Anderson, Richard L. Current opinion in ophthalmology:2013:24:5:488 -493

“Abstract

Purpose of review: Botulinum toxin (BTX) injections are the main medical treatment of facial dystonias, but injections are ineffective in some patients. This review discusses the indications for myectomy and surgical technique for treating benign essential blepharospasm (BEB) and apraxia of eyelid opening (ALO).

Recent findings: There are four reasons to consider myectomy for patients with BEB. The first is ALO associated with BEB. The second is patients with blepharospasm-associated deformities. The third is patients who are truly unresponsive to BTX. The fourth is patients who cannot afford or who refuse BTX injections.

Recent findings: There are four reasons to consider myectomy for patients with BEB. The first is ALO associated with BEB. The second is patients with blepharospasm-associated deformities. The third is patients who are truly unresponsive to BTX. The fourth is patients who cannot afford or who refuse BTX injections.

Summary: Myectomy remains essential for treating blepharospasm patients and the most common indication is those with associated ALO.

...

History

When myectomy was developed in the mid-1970s by senior author R.L.A., botulinum toxin (BTX) was not available. The only useful surgery prior to myectomy was facial neurectomy. Most neurectomies failed because of nerve regrowth and so-called ‘successful’ ones looked like bilateral facial nerve palsy. The myectomy at that time was, applied to all blepharospasm sufferers. Shortly thereafter, Dr Alan Scott studied botulinum A toxin in human volunteers and formed his company Oculinum, Inc.

In 1980, Scott first reported injecting botulinum A toxin into extraocular muscles to treat strabismus. In 1981, Mattie Lou Koster founded the BEBRF and R.L.A. first reported myectomy results. R.L.A. began using botulinum A toxin for blepharospasm in 1983 and Scott first reported treating blepharospasm with botulinum A toxin in 1985. Allergan acquired the distribution rights to Scott's botulinum A toxin product, Oculinum, in 1988. Oculinum, now named onabotulinum toxin A (Botox), was approved by the US Food and Drug Administration for blepharospasm and strabismus in 1989. Other botulinum A toxins such as abobotulinum toxin A (Dysport, Ipsen Biopharmaceuticals, Inc.), incobotulinum toxin A (Xeomin, Merz Pharma), and botulinum B toxin, also called rimabotulinum toxin B (Myobloc, US WorldMeds) have since been approved.

Currently, most myectomies are reserved for ‘failures’ or inadequate responses to BTX. True, BTX failures are rare, as less than 2% of the population does not respond. Patients can become refractory to BTX, especially with high doses used for generalized dystonia. However, even these numbers are overstated. If one questions immunity to or failure of BTX, placing 5–10 units in a forehead rhytid will determine whether it works. Antibody studies are useless.

...

Botulinum toxin failures

True BTX failure occurs in less than 2% of patients. Failure or resistance can be confirmed by injecting 5–10 units of BTX in a forehead rhytid and if nothing occurs, the patient is immune or refractory to the neurotoxin. Almost all inadequate responses or BTX ‘failures’ are because of ALO or droopy eyelids from ptosis, brow ptosis or dermatochalasis. Not recognizing these deformities and increasing BTX doses may further aggravate these conditions. Simple eyelid ptosis, brow ptosis, dermatochalasis, lid laxity, and eye dryness can be corrected by standard procedures and improves almost all BEB patients, unless they also have ALO or are truly immune to BTX.

...

Fewer surgeons may be performing the procedure because Medicare reimbursement has steadily declined. In 1976, Medicare reimbursed $3500 per side. In 1996, reimbursement was $1100 per side, in 2005 it was $100 per side, and in 2006 it dropped to zero. To offset this loss, surgeons can bill insurance for associated functional surgeries such as ptosis repair, blepharoplasty, and punctal occlusion.”


The authors preferred surgical technique is described in this reference.


2. Immunogenicity of botulinum toxins. Naumann M, Boo LM, Ackerman AH, Gallagher CJ.  J Neural Transm. 2013 Feb;120(2):275-90.

Abstract

Botulinum neurotoxins are formulated biologic pharmaceuticals used therapeutically to treat a wide variety of chronic conditions, with varying governmental approvals by country. Some of these disorders include cervical dystonia, post-stroke spasticity, blepharospasm, migraine, and hyperhidrosis. Botulinum neurotoxins also have varying governmental approvals for cosmetic applications. As botulinum neurotoxin therapy is often continued over many years, some patients may develop detectable antibodies that may or may not affect their biological activity. Although botulinum neurotoxins are considered "lower risk" biologics since antibodies that may develop are not likely to cross react with endogenous proteins, it is possible that patients may lose their therapeutic response. Various factors impact the immunogenicity of botulinum neurotoxins, including product-related factors such as the manufacturing process, the antigenic protein load, and the presence of accessory proteins, as well as treatment-related factors such as the overall toxin dose, booster injections, and prior vaccination or exposure. Detection of antibodies by laboratory tests does not necessarily predict the clinical success or failure of treatment. Overall, botulinum neurotoxin type A products exhibit low clinically detectable levels of antibodies when compared with other approved biologic products. This review provides an overview of all current botulinum neurotoxin products available commercially, with respect to the development of neutralizing antibodies and clinical response


These questions are from http://EyeQuiz.com.

Please send feedback, questions and corrections to tcooper@stanford.edu.  


Neuro-ophthalmology Question of the Week: Episodic Anisocoria

http://www.neurology.org/content/79/9/949.full.pdf+html?ct


Question:

Which condition is demonstrated in the above photos of episodic anisocoria?

1. Horner syndrome

2. Adie’s pupil

3. Tadpole pupil

4. Traumatic pupillary sphincter muscle tear

__________________________________________________


Correct Answer:

3. Tadpole pupil


Reference:

1. Tadpole pupil. Aki Kawasaki and Cedric Mayer, Neurology 2012;79;949

http://www.neurology.org/content/79/9/949.full.pdf+html?ct

A young woman has recurrent episodes of unilateral mydriasis lasting several minutes. The left pupil becomes large and deformed, described as “egg-shaped” (figure). Examination, including pharmacologic pupil tests, revealed no ophthalmologic or neurologic abnormalities. Cranio-orbital MRI was normal. Diagnosis of tadpole pupil was confirmed by self-taken photographs using a cellular phone.

Spontaneous segmental spasm of the iris dilator can cause pupillary distortion that resembles the shape of a tadpole.

Occasional patients with tadpole pupil have underlying Horner syndrome; otherwise, the syndrome is benign and self-limited. 1,2

Cellular phone “telemedecine” was particularly helpful in diagnosing this form of episodic mydriasis.

1. Thompson HS, Zackon DH, Czarnecki JS. Tadpole-shaped pupils caused by segmental spasm of the iris dilator muscle. Am J

Ophthalmol 1983;96:467– 477.

2. Balaggan KS, Hugkulstone CE, Bremner FD. Episodic segmental iris dilator muscle spasm: the tadpole-shaped pupil. Arch Ophthalmol 2003;121:744 –745.


2. Anisocoria. Sam Tapsell http://youtu.be/jgVJyEOXVvM 5 minute video


These questions are from http://EyeQuiz.com.

Please send feedback, questions and corrections to tcooper@stanford.edu.  


Neuro-ophthalmology Question of the Week: Isolated Ocular Motor Nerve Palsy

http://www.nanosweb.org/images/MicrovascularC_3_small.jpg

Question:

In patients age 50 years or older with an isolated ocular motor nerve palsy...

1. that is due a serious etiology, what percent will also have microvascular risk factor(s)?

a. 20%

b. 40%

c. 60%

2. the presence or absence of pain predicts whether the palsy is of a microvascular or non-microvascular in etiology?

a. true

b. false

_____________________________________________________

Correct Answers:

In patients age 50 years or older with an isolated ocular motor nerve...

1. that are due a serious etiology, what percent will also have microvascular risk factor(s)?

c. 60%

2. the presence or absence of pain predicts whether a palsy is microvascular or non-microvascular in etiology?

b. false


References:

1. Isolated Third, Fourth, and Sixth Cranial Nerve Palsies From Presumed Microvascular Versus Other Causes: A Prospective Study

Tamhankar MA, Biousse V, Ying GS, et al. Ophthalmology. 2013;120:2264-2269


Purpose: To estimate the proportion of patients presenting with isolated third, fourth, or sixth cranial nerve palsy of presumed microvascular origin versus other causes.

Design: Prospective, multicenter, observational case series.

Participants: A total of 109 patients aged 50 years or older with acute isolated ocular motor nerve palsy.

Testing: Magnetic resonance imaging (MRI) of the brain.

Main Outcome Measures: Causes of acute isolated ocular motor nerve palsy (presumed microvascular or other) as determined with early MRI and clinical assessment.

Results: Among 109 patients enrolled in the study, 22 had cranial nerve III palsy, 25 had cranial nerve IV palsy, and 62 had cranial nerve VI palsy. A cause other than presumed microvascular ischemia was identified in 18 patients (16.5%; 95% confidence interval, 10.7-24.6). The presence of 1 or more vasculopathic risk factors (diabetes, hypertension, hypercholesterolemia, coronary artery disease, myocardial infarction, stroke, and smoking) was significantly associated with a presumed microvascular cause (P ¼ 0.003, Fisher exact test).

Vasculopathic risk factors were also present in 61% of patients (11/18) with other causes. In the group of patients who had vasculopathic risk factors only, with no other significant medical condition, 10% of patients (8/80) were found to have other causes, including midbrain infarction, neoplasms, inflammation, pituitary apoplexy, and giant cell arteritis (GCA). By excluding patients with third cranial nerve palsies and those with GCA, the incidence of other causes for isolated fourth and sixth cranial nerve palsies was 4.7% (3/64).

Conclusions: In our series of patients with acute isolated ocular motor nerve palsies, a substantial proportion of patients had other causes, including neoplasm, GCA, and brain stem infarction. Brain MRI and laboratory workup have a role in the initial evaluation of older patients with isolated acute ocular motor nerve palsies regardless of whether vascular risk factors are present.


In addition:

  • “Age and sex distributions were similar in patients with and without presumed microvascular palsies.”

  • “Sixty percent of the cohort (n=65) experienced pain or headache in association with double vision, and the presence or absence of pain was not predictive of the cause of the palsy.”


2. http://www.ophthobook.com/ Timothy Root, MD http://rooteyenetwork.com/websites/


                            
3rd Nerve Palsy                          4th Nerve Palsy


                      

These questions are from http://EyeQuiz.com.

Please send feedback, questions and corrections to tcooper@stanford.edu.  


Neuro-ophthalmology Question of the Week: Optic Tract Signs

The right optic tract is hyperintense on the FLAIR axial MRI

Am J Ophthalmol 2007;143:772-80.

Which of the following findings are compatible with an optic tract lesion?

1. Contralateral visual field defect

2. Ipsilateral visual field defect

3. Incongruous homonymous hemianopia

4. Congruent homonymous hemianopia

5. Complete homonymous hemianopia

6. Relative afferent pupillary defect on the side ipsilateral to the lesion

7. Relative afferent pupillary defect on the side contralateral to the lesion

8. Optic atrophy

________________________________________________________


Correct Answers:

1. Contralateral visual field defect

3. Incongruous homonymous hemianopia

4. Congruent homonymous hemianopia

5. Complete homonymous hemianopia

7. Relative afferent pupillary defect on the side contralateral to the lesion

8. Optic atrophy


References:

1. Pearls & Oy-sters: Optic tract syndrome, Rodriguez AR & Reddy K.

Neurology 75:e86-7:2010. Divisions of Ophthalmology and Neuro-Surgery, Department of Surgery, McMaster University, Hamilton, Canada.


PEARLS

• The optic tract syndrome is characterized by a contralateral, incongruous homonymous hemianopia, contralateral relative afferent pupillary defect (RAPD), and optic atrophy due to retrograde axonal degeneration.

• Optic disc pallor often results in a pattern of bowtie atrophy of the eye with temporal field

loss and atrophy of the upper and lower poles of the disc of the eye with nasal field loss.

• Visual acuity and color vision are usually normal unless there is bilateral involvement or extension to the chiasm or optic nerve.

OY-STERS

• Homonymous hemianopia is typically incongruous in optic tract lesions although this concept only applies if the defect is incomplete. Complete homonymous hemianopia is of no localizing value.

• Behr’s pupil (larger pupil on the side opposite to the lesion) and pupillary hemiakinesia (Wernicke sign) are historical signs that are not helpful in the clinical setting


Behr’s pupil: Behr's pupil sign reported with lesions of the optic tract is an anisocoria with the larger pupil in the contralateral eye. It has been largely discredited. Neuro-ophthalmology, Glaser JS, 1990 JB Lippincott Company


Wernicke sign:  In hemianopia, a reaction due to damage of the optic tract, consisting in loss of pupillary constriction when the light is directed to the blind side of the retina; pupillary constriction is maintained when light stimulates the normal side. This sign cannot be seen with a bright light because of intraocular scatter onto the seeing half of the retina.http://www.medilexicon.com/medicaldictionary.php?s=Wernicke+reaction


2. Visual fields in neuro-ophthalmology. Kedar S, Ghate D, Corbett JJ. Indian J Ophthalmol [serial online] 2011 [cited 2013 Dec 5];59:103-9. Available from: http://www.ijo.in/text.asp?2011/59/2/103/77013

Retrochiasmal disorders

Retrochiasmal disorders produce varied patterns of homonymous hemianopia, depending on the site of the lesion. Before the advent of modern neuroimaging, these patterns were used to localize a lesion in the visual pathway. However, a recent study has shown that the visual field defects may not be as specific to a given location as was previously believed. [55] Lesions anywhere along the retrochiasmal pathway can produce virtually any type of homonymous visual field deficit, except a unilateral loss of the temporal crescent and homonymous sectoranopia that are produced exclusively by anterior occipital and geniculate lesions, respectively. Contrary to existing and persistent belief, almost 50% of lesions involving the optic tracts produce congruent homonymous hemianopia even though they have a reputation for being notoriously incongruous. [56]Congruent homonymous hemianopias are produced by posterior pathway lesions and the chance that a congruent homonymous hemianopia is produced by a lesion involving the occipital lobe was estimated to be 56%.

Optic tract lesion - Homonymous hemianopia (50% congruent and 50% incongruent)

3. Congruency in homonymous hemianopia. Kedar S, Zhang X, Lynn MJ, Newman NJ, Biousse V. . Am J Ophthalmol 2007;143:772-80.

FIGURE 6. Congruent homonymous hemianopia (HH) from optic tract lesion. (Left) Goldmann visual fields showing a congruent right homonymous superior quadrantic visual field defect associated with a right homonymous scotomatous defect secondary to a left optic tract lesion (Right, arrow) after a posterior GPi pallidotomy for Parkinson disease. (Reprinted with permission from Biousse V, Newman NJ, Carroll C, et al. Visual fields in patients with posterior GPi pallidotomy. Neurology 1998;50:258–265).



FIGURE 7. Congruent homonymous hemianopia (HH) from a demyelinating optic tract lesion in a patient subsequently diagnosed with multiple sclerosis. (Left) 24-2 SITA-fast Humphrey visual field test (grayscale and pattern deviation) showing a congruent left incomplete HH secondary to a right optic tract lesion (Right). The right optic tract is hyperintense on the FLAIR axial MRI (Right).


These questions are from http://EyeQuiz.com.

Please send feedback, questions and corrections to tcooper@stanford.edu.  


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