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we describe the case of a male patient who presented with anisocoria , and was initially diagnosed with an acute adie 's tonic pupil . on subsequent laboratory testing , he was found to have neurosyphilis .
this case underscores the importance of considering this diagnosis in patients with acute onset internal ophthalmoplegia and hypersensitivity to dilute pilocarpine , even in the absence of other oculomotor nerve findings .
a 39-year - old man presented to our clinic with complaints of an enlarged right pupil of onset 10 days prior .
he initially noted a difference in the pupil size while looking at his eyes in the mirror , and complained of progressively worsening light sensitivity in the right eye .
in addition , he described blurred vision with reading and near work , which improved on covering his right eye .
he denied a recent history of headaches , diplopia , ptosis or blurred vision at distance .
he also denied a previous history of ocular trauma , use of scopolamine patches or recent upper respiratory infection symptoms .
the best - corrected visual acuity was 20/20 in the right eye and 20/15 in the left eye .
the visual fields were full to confrontation , but on frequency doubling technology ( fdt ) visual field testing , he was noted to have an inferior altitudinal defect in the left eye ( fig .
anisocoria was present , with the right pupil measuring 7.5 mm and the left pupil 4 mm in the light . in the dark , the right and left pupils measured 8 and 7.5 mm , respectively .
pupils were also tested on convergence , and measured 6 mm in the right and 3 mm in the left .
a sluggish response was noted on redilation of the right pupil in going from near to distance vision .
the patient also had a small left relative afferent pupillary defect ( rapd ) by the reverse rapd technique .
the anterior chamber was deep and quiet bilaterally , and no iris sphincter tears or other signs of previous ocular trauma were noted in the right eye .
no vermiform movements were seen , but an atonic segment was present inferotemporally in the iris collarette . given the clinical picture of anisocoria worse in the light and the tonicity noted in the right pupil on distance fixation after convergence , pharmacological testing was undertaken with dilute pilocarpine ( fig .
a drop of dilute pilocarpine ( 0.125% ) was instilled in each eye , and the pupil sizes were measured at the same illumination at 5 , 15 , and 30 min intervals .
reversal of the anisocoria was noted after 30 min , with the pupils measuring 2.5 and 4 mm in the right and left eyes , respectively .
this was consistent with denervation hypersensitivity of the right pupil and a diagnosis of an acute right adie 's tonic pupil .
homes - adie 's syndrome was ruled out on testing of the peripheral reflexes , which were within normal limits bilaterally .
on dilated fundus examination , superior optic disc pallor was noted in the left eye ( fig .
there was slight cup - to - disc ratio asymmetry ( 0.3 mm in the right eye and 0.45 mm in the left eye ) , but the pallor was out of proportion to the cupping .
associated with this sectoral disc pallor in the left eye , there was slight attenuation of the superior arcades .
the vitreous , macula , vessels , and periphery were within normal limits in the right eye . on red saturation test , the patient volunteered having noticed decreased color intensity in the left eye for the last 2 years .
however , on ishihara pseudoisochromatic plate testing , he was able to correctly identify all plates in both eyes . based on these findings in the left eye , an enhanced magnetic resonance imaging ( mri )
brain and orbits study was obtained , which revealed enhancement of the right oculomotor nerve , along its cisternal segment into the oculomotor cistern of the superior right cavernous sinus ( fig .
3 ) . no orbital or intracranial mass was seen , and there was no evidence of previous demyelinating disease .
considering the unlikelihood of an adie 's tonic pupil in a male patient , his previous history of genital herpes , and the lack of a viral prodrome or any other cause to justify this diagnosis of exclusion , rapid plasmin reagent ( rpr ) , venereal disease research laboratory ( vdrl ) , and fluorescent treponemal antibody ( fta - abs ) tests were ordered .
these tests were all positive and the patient was diagnosed with probable neurosyphilis per hooshmand 's criteria .
a peripherally inserted central catheter was placed , and the patient was treated with a 3-week course of procaine penicillin g.
our patient 's presentation was initially consistent with that of an acute adie 's tonic pupil given the decreased light and convergence responses , tonicity after accommodation , hypersensitivity to dilute pilocarpine , and the inferotemporal atonic iris segment noted in the right eye . in light of this unusual presentation , the patient 's right internal ophthalmoplegia and left optic neuropathy were further investigated .
positive syphilis serologies clinched the diagnosis , which was confirmed by enhancement of the right preganglionic oculomotor nerve on mri .
this was omitted by the infectious disease specialist as it would not have altered the treatment of the patient .
the differential diagnosis of unilateral internal ophthalmoplegia in a young patient includes ocular or orbital trauma , uveitis , acute viral illness , cycloplegic medication use , aneurysm ( early posterior communicating artery or internal carotid artery ) , direct or indirect ( i.e. uncal herniation ) compressive oculomotor neuropathy secondary to an orbital or intracranial mass , nothnagel syndrome , miller - fisher syndrome , leptomeningeal disease , and adie 's tonic pupil . on physical examination
the patient had a left optic neuropathy , but denied a history of previous head trauma , and no signs of optic nerve atrophy or healed fractures were seen on mri .
he was also asked about a viral prodrome or history of previous eye infection , which he denied as well .
there was likewise no history of mydriatic medication use , and this was ruled out on pupil examination .
compression of the oculomotor nerve by an early aneurysm usually results in subtle ocular motility deficits and/or ptosis , and the presence of an aneurysm was also effectively ruled out on mri .
fascicular involvement was not seen clinically or on mri , and on neurologic testing the patient did not exhibit ataxia or areflexia . finally , the patient did not have a history of malignancy and the right oculomotor nerve enhancement on mri was not typical of leptomeningeal disease .
true to its epithet as  the great imitator , syphilis may affect almost any part of the eye and present as an interstitial keratitis , scleritis , uveitis ( anterior , intermediate , posterior or panuveitis ) , retinal vasculitis , chorioretinitis , optic neuropathy or as a new - onset cranial nerve palsy [ 2 , 3 ] . in our case ,
the only positive findings were a right internal ophthalmoplegia simulating an acute adie 's tonic pupil and a chronic , subacute left optic neuropathy .
on review of the literature , there are several case reports of adie 's tonic pupils on patients with neurosyphilis , in most of which bilateral pupillary involvement has been described [ 47 ] . to our knowledge , this is the second report of unilateral internal ophthalmoplegia as a presenting sign of neurosyphilis .
we believe that only one pupil was involved due to an early presentation of the disease , as our patient manifested no other neurological symptoms aside from a mild visual disturbance associated with a previous left optic neuropathy . the patient 's left optic neuropathy may have been related to a self - limited treponemal infection of the optic nerve or to another process .
while retinal arteriolar attenuation has been associated with syphilitic optic neuropathy , this usually results in a fast decline in visual acuity .
however , other causes are less likely in this young patient , including glaucoma ( degree of cupping was out of proportion to the pallor and the extent of visual field loss ) , previous optic neuritis ( usually presents with a central or cecocentral scotoma , and the patient did not have optic nerve enhancement or signs of demyelinating disease on mri ) , nutritional and/or toxic optic neuropathy ( a bilateral , albeit asymmetrical central or cecocentral visual field defect would have been expected ) , and leber 's hereditary optic neuropathy ( usually results in a fast decline in visual acuity in both eyes , and diffuse optic disc pallor would have been expected ) .
the patient 's left inferior altitudinal visual field defect may have resulted from treponema - induced vasculitis of the superior branch retinal arteries with subsequent atrophy of the nerve fiber layer in their distribution .
this case underscores the importance of keeping neurosyphilis in the differential of patients with unilateral ophthalmoplegia , particularly male patients in which a diagnosis of an adie 's tonic pupil is three times less likely .
a thorough sexual history in these cases is helpful , but this may not be readily elicited .
in these cases , a complete ophthalmic and neurologic examination should be conducted to rule out other subtle coexisting pathologies as in the case of our patient . in early cases of neurosyphilis ,
prompt diagnosis affords the possibility of a cure , before the onset of the severe vascular , neurologic , and psychiatric complications that may result in death .
abstractwe describe the case of a male patient who presented with anisocoria , and was initially diagnosed with an acute adie 's tonic pupil . on subsequent laboratory testing , he was found to have neurosyphilis . 
 magnetic resonance imaging demonstrated enhancement of the right oculomotor nerve . 
 this case underscores the importance of considering this diagnosis in patients with acute onset internal ophthalmoplegia and hypersensitivity to dilute pilocarpine , even in the absence of other oculomotor nerve findings .