• 12 SECTION Disorders Pupil

Argyll Robertson Pupils

Key Facts

•Unilateral or bilateral miosis and usually anisocoria

•Affected pupil fails to constrict to light but does constrict to a near target (light–near dissociation)

•Affected pupils lack tonic features, segmental palsy, or denervation supersensitivity

•Associated with positive syphilis serology and other neurologic manifestations of syphilis, especially tabes dorsalis

•Location of responsible lesion is unknown

Clinical Findings

•Unilateral or bilateral miosis and usually anisocoria

•Affected pupil fails to constrict to light but does constrict to a near target (light–near dissociation)

•Affected pupils lack tonic features, segmental palsy, or denervation supersensitivity

•Neurologic manifestations of syphilis may be present

Ancillary Testing

• Positive syphilis serology in serum or spinal fluid in some cases

Differential Diagnosis

•Miosis caused by instillation of pharmacologic agent

•Tonic pupil

•Iris damage from trauma, inflammation, ocular surgery or laser treatment, congenital anomaly

•Denervated pupils in autonomic neuropathy

Treatment

• Directed at underlying condition

Prognosis

•Pupil findings do not change

•Patients are not symptomatic from pupil abnormality

A

B

C

D

Fig. 12.2 Bilateral Argyll Robertson pupils. (A) In darkness, both pupils are slightly small. (B) In brightness, neither pupil constricts. (C) When a target is viewed at reading distance, both pupils constrict normally. (D) After instillation of 1/10% pilocarpine in each eye, neither pupil constricts.

Pupils Robertson Argyll

• 12 SECTION Disorders Pupil

Tectal (Dorsal Midbrain) Pupils

Key Facts

•Anisocoria may be present

•Bilateral dilated pupils that do not constrict or constrict poorly to light but may constrict normally to a near target (tectal light–near dissociation)

•Lesion affects dorsal (tectal) midbrain

•If it extends ventrally into tegmental midbrain, pupils do not constrict to a near target

•Pupil abnormality attributed to disconnection of tectal midbrain portion of afferent pupil reflex pathway from efferent parasympathetic (Edinger–Westphal) nuclei

•Common causes:

•hydrocephalus

•pineal region or midbrain tectal tumor

•demyelinization

•infarction

Clinical Findings

•Bilateral light–near dissociated mydriatic pupils

•Other features of dorsal midbrain syndrome:

•lid retraction

•vertical gaze deficit

•convergence–retraction “nystagmus”

•hypertropia

•torsional nystagmus

Ancillary Testing

•MRI may show ventriculomegaly or signal abnormalities in pineal or midbrain tectal regions

Differential Diagnosis

•Bilateral tonic pupils

•Iris atrophy from ocular surgery, trauma, ischemia, or congenital anomaly

•Botulism

•Denervated pupils in autonomic neuropathy

Treatment

• Depends on underlying condition

Prognosis

• Depends on underlying condition

A

B

C

D

Fig. 12.3 Tectal (dorsal midbrain) pupils. (A) In dim illumination, both pupils are larger than normal, but unequally. (B) In bright light, neither pupil constricts. (C) When a target is viewed at reading distance, both pupils constrict normally. (D) After instillation of 1/10% pilocarpine in each eye, neither pupil constricts.

A B

Fig. 12.4 Tectal glioma. Postcontrast (A) sagittal and (B) axial T1 MRI shows enhancing cystic mass in tectal region (arrow).

Pupils Midbrain) (Dorsal Tectal