CONSTRICTED PUPILS (MIOSIS)
The best method to develop a list of the causes of a constricted pupil
is to use neuroanatomy. One simply follows the nerve pathways from the
end organ (iris) through the peripheral portion of the nerves to the central
nervous system (brainstem) (Table 18).
-
End organ. Iritis, keratitis, or the cholinergic drugs may be the
cause of the constricted pupil in this location. Hyperopia and presbyopia
are also possible causes.
-
Peripheral nerves. Constriction of the pupil may occur from lesions
anywhere along the sympathetic pathway as it branches around the internal
carotid artery (aneurysms, thrombosis, and migraine), enters the stellate
ganglion in the neck (scalenus anticus syndrome, tumors or adenopathy in the
neck), and follows the preganglionic pathway into the spinal cord (aneurysm
of the aorta, mediastinal tumors, spinal cord tumors, or other
space-occupying lesions).
-
Central nervous system. Lesions involving the sympathetic pathways
of the brainstem (posterior inferior cerebellar tumors, occlusion, brainstem
tumors, hemorrhages, encephalitis, or toxic encephalopathy) will cause
miosis. Both pupils are constricted in the Argyll Robertson pupil of
neurosyphilis in which the damage is located in the pretectal nucleus of the
midbrain. Morphine characteristically causes bilateral constriction of the
pupils, probably based on its central nervous system effects.
Approach to the Diagnosis
In unilateral miosis, the clinician must look for local conditions such
as iritis and keratitis. If there is an associated ptosis and enophthalmos,
Horner syndrome is present. The lesion is undoubtedly located somewhere
along the sympathetic pathway. Miosis alone, however, may be due to a
sympathetic lesion. Bilateral miosis and coma should suggest narcotic
intoxication or a brain stem lesion (possibly a pontine hemorrhage).
Bilateral miosis in an alert individual with pupils that fail to react to
light but react to accommodation is clear evidence of an Argyll Robertson
pupil. Partial Argyll Robertson pupils do occur. Bilateral miosis in older
individuals without loss of the light reflexes suggests hyperopia or
arteriosclerosis.
The laboratory workup may include an x-ray film of the cervical spine, chest
and skull roentgenogram, a CT scan or MRI of the brain, and a spinal tap or
arteriograms, depending on the association of other symptoms and signs. A
starch test to determine if sweating function is lost on the side of the
lesion will help locate the level of the sympathetic nerve lesion.
Other Useful Tests
-
Venereal disease research laboratory (VDRL) test (neurosyphilis)
-
Histoplasmin skin test (iriditis)
-
Toxoplasma serology (iridocyclitis)
-
Epinephrine test (Horner syndrome)
-
Slit lamp examination (iriditis, keratitis)
-
Tonometry (glaucoma)
-
Mecholyl test (Argyll Robertson pupil)
Pictures
Book Source Details
- Book Title: Differential Diagnosis in Primary Care
- Author(s): R. Douglas Collins MD, FACP
- Year of Publication: 2007
- Copyright Details: Differential Diagnosis in Primary Care, Copyright © 2007 Lippincott Williams & Wilkins.
Other Book Chapters Related to Pupil symptoms
Read excerpts from these other book chapters related to Pupil symptoms:
Medical Books Excerpts
- Mydriasis
- "Handbook of Signs & Symptoms (Third Edition)" (2006)
- [ read ]
- Mydriasis
- "Professional Guide to Signs & Symptoms (Fifth Edition)" (2006)
- [ read ]
- Mydriasis
- "Signs & Symptoms: A 2-in-1 Reference for Nurses" (2007)
- [ read ]
- Mydriasis
- "Nursing: Interpreting Signs and Symptoms" (2007)
- [ read ]
Copyright Details: Differential Diagnosis in Primary Care, Copyright © 2008 Williams & Wilkins.
More About Causes of Pupil symptoms
» Next page: Videos relating to Pupil symptoms
Rate This Website
What do you think about the features of this website?
Take our user survey and have your say:
Website User Survey
Medical Tools & Articles:
Next articles:
Tools & Services:
Medical Articles:
Forums & Message Boards
- Ask or answer a question at the Boards:
