Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
Key Concepts
-
The diagnostic approach to diplopia is aimed at determining (1) if the diplopia is monocular, (2) if there is a restrictive or mechanical issue in the orbit or orbital structures, (3) if there is a palsy of one or more of the oculomotor cranial nerves, (4) if there is a neuroaxial process involving the brainstem and related cranial nerves, or (5) if there is a systemic neuromuscular process.
-
Monocular diplopia is most commonly caused by an ophthalmologic problem related to refractory distortions or retinal buckling.
-
Binocular diplopia resolves when either eye is closed and is the result of a misalignment in the visual axes.
-
Important historical features in assessing diplopia includes onset, directionality and orientation of the diplopia; presence of pain, and the presence of other associated symptoms.
-
An isolated CN III palsy presents with diplopia in all directions of gaze, except on lateral gaze to the affected side; the eye is deviated down and out; ptosis and a dilated pupil may also be present.
-
A CN IV palsy results in vertical or torsional diplopia that worsens on looking down and toward the nose.
-
A CN VI palsy will cause the affected eye to turn inward and results in diplopia that worsens on lateral gaze toward the affected side.
-
Cavernous sinus or posterior orbit disease (orbital apex syndrome) may present with ipsilateral diplopia involving CN III, IV and or VI; associated symptoms may include pain, exophthalmos, chemosis, and possibly ipsilateral periorbital facial numbness or dysesthesia.
-
Multiple sclerosis or localized pathology in the brainstem, such as tumor, lacunar infarct, basilar artery thrombosis, vertebral artery dissection or ophthalmoplegic migraine, may present with focal lesions presenting as diplopia.
-
The diplopia caused by myasthenia gravis is associated with ptosis, gets worse as the patient fatigues, and improves with rest or on placing ice over the eye.
-
Initial treatment for diplopia is directed toward imminent threats to airway and ventilation (e.g., with botulism and myasthenia gravis) and immediate or rapidly evolving threats to the central nervous system (CNS) (e.g., stroke, meningoencephalitis or Wernicke encephalopathy).
Foundations
Diplopia (double vision) can be either monocular or binocular. Although life-threatening diagnoses are rare, ED patients have a higher incidence of harboring a serious neurological process than patients presenting in the ambulatory setting. Most ED cases are binocular, with cranial nerve palsies being the most common cause.
Pathophysiology
Double vision or diplopia is seeing two or more images. The etiology can be from systemic disease or pathology in the eye or brain. Monocular diplopia does not correct when one eye is closed and is usually caused by intraocular pathology, for example, lens subluxation, retinal abnormalities, or a refractive error, in which case the diplopia should resolve with pinhole testing.
Binocular diplopia is double vision that resolves when one eye is closed. It is caused by misalignment of the visual axes, and has an extensive differential diagnosis: see Table 17.1 . Approximately one-third of patients presenting to the ED with binocular diplopia have a secondary cause, such as stroke, multiple sclerosis, brain tumors, and cerebral aneurysms.
TABLE 17.1
Differential for Binocular Diplopia
| Structural Orbitopathy: | Trauma Infection/abscess Craniofacial masses |
| Orbital Myositis: | Thyroid eye disease Wegener granulomatosis Giant cell arteritis Systemic lupus erythematosus Dermatomyositis Sarcoidosis Rheumatoid arthritis Idiopathic orbital inflammatory syndrome (orbital pseudotumor) |
| Isolated Oculomotor Nerve Palsy: Cranial nerve III Cranial nerve IV Cranial nerve VI |
Multiple sclerosis Hypertensive vasculopathy Diabetic vasculopathy Idiopathic intracranial hypertension Compression Trauma |
| Multiple Oculomotor Nerve Palsies: | Cavernous sinus infection, mass, vasculitis or thrombosis Orbital apex syndrome |
| Neuroaxial Process Involving the Brainstem and Related Cranial Nerves: | Focal:
Localized brainstem process:
Diffuse (involving the brainstem and/or CNs III, IV, and VI)
|
| Neuromuscular Disorder: | Myasthenia gravis Botulism |
CN , Cranial nerve.
Cerebral diplopia, or polyopia, is seeing many images and can be monocular or binocular. It is rare and associated with stroke, vascular spasm, tumor, multiple sclerosis, trauma, infections, or seizures, primarily involving the occipital or temporal lobes.
Diagnostic Approach
Differential Considerations
Monocular diplopia is an ophthalmologic problem related to distortions in the light path from dry eyes, a corneal irregularity, cataract, lens dislocation, or retinal wrinkles involving the macula. In rare cases, monocular diplopia may be the presenting complaint in conversion disorder, but this is a diagnosis of exclusion. Box 17.1 outlines some key causes of monocular diplopia.
BOX 17.1
Key Causes of Monocular Diplopia
-
Dry eyes
-
Corneal irregularity
-
Cataract
-
Lens dislocation
-
Retinal wrinkles
-
Conversion disorder
Binocular diplopia may be due to a mechanical or restrictive process in the orbit or structures of the orbit, a palsy of one or more of the oculomotor cranial nerves, a proximal neuroaxial process involving the brainstem and related cranial nerves, a systemic neuromuscular process, or trauma. Table 17.1 outlines some key causes of binocular diplopia.
The clinical approach in the ED entails narrowing the differential diagnosis to those diagnoses that may result in rapid and profound morbidity, in distinction from those that are less acute. In most cases a systematic history and physical exam will elicit the underlying etiology.
Pivotal Findings
History
The history begins by determining if the diplopia is monocular or binocular. Additional information helpful in formulating the differential diagnosis in diplopia includes: (1) the timing of onset and symptoms; (2) directionality and orientation of the diplopia (horizontal, vertical, or torsional); (3) presence of pain; and (4) presence of other associated symptoms. In terms of the timing, sudden onset suggests an ischemic, cerebrovascular, or microvascular cause, especially if the intensity or degree of diplopia is maximal at onset. A fluctuation of symptoms over time may suggest transient ischemic attacks or an impending stroke, but more generally implies a neuromuscular disease.
The directionality of the diplopia is as important as the type of diplopia. The directions of gaze that elicit or worsen the diplopia and the general orientation of that diplopia—horizontal, vertical, torsional—should be carefully determined to localize the problem. Diplopia can be horizontal with the images side by side, vertical with the images above and below each other, or torsional. Horizontal diplopia, without vertical separation, is often indicative of medial or lateral rectus muscle pathology, whereas torsional diplopia is more commonly caused by superior or inferior oblique muscle dysfunction or lateral medullary syndrome. Vertical diplopia is most commonly associated with brain or brainstem pathology but can been seen with CN IV palsy.
Important associated symptoms include vision changes, periorbital pain, pain with eye movement, ptosis, and systemic symptoms such as headache, nausea, vomiting, generalized weakness, and neurological deficits. In the absence of trauma, the presence of pain suggests an inflammatory or infectious process and narrows the differential significantly. Associated neurological symptoms concerning for cerebrovascular disease include vertigo, dizziness, ataxia, or aphasia.
Other critical components of the history include: progression of the symptoms, relieving or exacerbating symptoms, trauma, and past medical and family history. A history of progressive symptoms raises concern for a compressive lesion, whereas intermittent diplopia, especially if associated with ptosis, raises concerns for a neuromuscular junction disorder such as myasthenia gravis. In addition, a history of worsening symptoms throughout the day that improve with rest also raises concerns for myasthenia gravis. Past medical history should focus on immune system compromise and vascular risk factors such as hypertension, diabetes, coronary artery disease, and smoking. Family history should include questions about multiple sclerosis, lupus, and vascular diseases.
Physical Exam
The physical exam includes a complete neurological exam with particular attention on the cranial nerves. The provider should focus on any subtle findings, including head positioning, facial asymmetry, cranial nerve abnormalities, extremity weakness, and sensory deficits. Binocular diplopia, due to cranial nerve pathology on one side of the body, with neurological deficits involving the contralateral side of the body, raises the suspicion for brainstem pathology.
The eye exam should include the external eye exam, a visual acuity and visual field exam, a pupil exam, the extraocular muscle exam, a funduscopic exam, and a slit lamp exam to look at the anterior chamber as well as intraocular pressure measurements. If there is concern for increased intracranial pressure, a bedside ultrasound can be done to look for papilledema.
The external eye exam
The external eye exam includes an exam of the orbital and periorbital structures. The conjunctiva is examined for signs of injection, inflammation, chemosis, or hemorrhage. Document head positioning, proptosis, ptosis, and lid lag, as well as evidence of trauma. A patient presenting after trauma to the eye may have orbital fractures causing entrapment of the extraocular muscles, most commonly the inferior rectus muscle, which prevents the affected eye from tracking with the nonaffected eye on upwards gaze, resulting in diplopia, or a proptotic eye secondary to a retrobulbar hematoma. In addition, space-occupying lesions of the orbit can cause unilateral proptosis, and systemic diseases—for example, thyroid disease—can cause bilateral proptosis or myopathy resulting in diplopia.
You're Reading a Preview
Become a Clinical Tree membership for Full access and enjoy Unlimited articles
If you are a member. Log in here