neuro-ophthalmology

Horner Syndrome: Pharmacologic Diagnosis

Horner syndrome describes the constellation of findings associated with a lesion affecting the oculosympathetic pathway. Clinically, ipsilateral miosis, ptosis, and anhidrosis form the classic triad, with other features potentially being present.

Without getting into too much detail about the sympathetic pathways and differential diagnosis of Horner syndrome (those will be covered in other articles), I will attempt to highlight the 3 pharmaceutical agents used in the diagnosis of Horner syndrome, discuss the tests, and point out the key ideas that often find themselves in tests.

Diagnostic Criteria For Pseudotumor Cerebri (Idiopathic Intracranial Hypertension)

Pseudotumor cerebri syndrome (PTC, also referred to as idiopathic intracranial hypertension [IIH]) is classically taught as presenting in young, overweight women of childbearing age, with a history of headaches and findings of bilateral optic nerve swelling, associated with an elevated intracranial pressure.  However, as with every "textbook" definition of a disease, there are atypical cases (children, men, thin people, older people), and so I am often confronted with some interesting diagnostic challenges when I am referred a patient that does not fit the typical picture of PTC who has bilateral optic nerve swelling.

Ciliary Ganglion

The ciliary ganglion serves as the site of synapse for the parasympathetic nerves innervating the eye.  Because of the many nerves that course through it (not all of them synapse!) and its anatomical location, this structure is of importance in learning the basics of ophthalmology.  According to the Basic and Clinical Science Course, it is located lateral to the ophthalmic artery, situated between optic nerve and lateral rectus muscle, approximately 1 cm (10 mm) anterior to the annulus of Zinn and 1.5-2 cm (15-20 mm) posterior to the globe (1-5).

Phakomatoses: Overview

Phakomatoses are a multidisciplinary category of systemic diseases that is often tested for a multitude of reasons.  Although the incidence of these conditions is fairly low (though chances are you will see at least 1 case of many of these conditions), there are many ocular findings that need to be considered.

I've been debating how to organize this information in a useful manner for review for quite some time.  The subject material is pretty massive, and each condition could easily take several articles (and probably eventually will).  But I wanted to make sure there was a useful review out there on this subject before the written board exam, in case the test covers one of these conditions.

Congenital Optic Disc Anomalies

Funny-looking optic discs are a "fun" diversion in an ophthalmology clinic (sarcasm implied here).  What was initially a routine exam immediately turns into an agonizing "is this normal or not" exercise.  Part of the angst that comes from seeing anomalous optic discs is that some of the congenital disc anomalies are associated with systemic diseases.  If there is concurrent visual field loss or decreased visual acuity, the challenge becomes deciding if those defects in the visual system are due to the anomalous nerve, or if there is some other ophthalmic cause that we don't want to miss.

Optociliary Shunt Vessels

Optociliary shunt vessels (retinochoroidal shunts), are normal congenital collaterals between the retinal and choroidal venous circulation.  In conditions that cause chronic central retinal vein obstruction, venous outflow becomes redirected to the choroidal venous circulation, resulting in dilation of these collateral vessels.

Papilledema

Neuro-ophthalmology tends to have some of the more challenging questions, depending on your level of knowledge or comfort with these topics.  One of the important things to recognize and evaluate is the swollen optic nerve.

The 8 Causes of Tunnel Visual Fields

There are relatively few causes for tunnel visual fields (or “gun barrel” visual fields), which is a relatively common finding in neuro-ophthalmology.  There are 8 major categories of tunnel visual fields, which can be determined systematically through careful history and examination.  This differential diagnosis is adopted from Duane’s Clinical Ophthalmology.