The Curious Receptionist
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The Royal Melbourne Hospital Melbourne, Australia April, 2011 |
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The Tale
We begin our story with a personable young office receptionist, only 19 years of age. She had recently commenced her new office job, and had no particular complaints about it until a particular problem occurred. One busy day while she was working away at the office, she lost the vision in her right eye - the vision in the eye first became blurry, and then the vision gradually darkened over the next several hours until the right eye was blind. She could not see out of it at all, not even movement. While this would profoundly disturb most people, our receptionist curiously finished her working day while this all happened, when most people might have left a tad early so as to seek immediate help.
Regardless, these events did prompt our receptionist to visit an ophthalmologist that afternoon, who could not observe any right eye pathology. The retina (the light-sensitive layer of tissue lining the inner surface of the eye) appeared healthy, as did the optic disc (the beginning of the optic nerve which carries visual information from the retina to the brain). He ordered a magnetic resonance angiogram (MRI) scan (a radiological technique that uses strong magnetic fields and radiowaves to assess the movement of water molecules within body tissues, creating an anatomical image) the next day, and the brain appeared normal. The ophthalmologist reviewed her again three days after her visual loss, and again noted no obvious right eye pathology. The ophthalmologist was decidedly stumped, and referred his half-blind patient to our hospital.
Being on ward service, I wandered over to see our newest arrival. I noted that our receptionist was a young lady of European ancestry and an average build. She was a little shaken up by what had happened, but appeared to be well in control of her emotions. Noting the recent events, I pressed on with more history. She had polycystic ovarian syndrome (a not entirely understood condition that affects young women and is associated with menstrual disorders, infertility, high levels of masculinizing hormones, and insulin resistance) and suffered from frequent headaches on most days of the week. She did not smoke, drink alcohol, or use illicit drugs, and claimed to be under no current personal or financial stress. There was no family history of vision loss, and she took no regular medications (not even the oral contraceptive pill) and had no drug allergies.
On examination, our receptionist was alert and aware. The visual acuity in her left eye was normal, but with her right eye she could perceive only bright light shined directly onto the eye - no more. I brought out my faithful ophthalmoscope (a device that allows one to see the internal eye structures) and took a closer look at her optic disc. Although the ophthalmologist had noted it to be normal a few days before, pathology can sometimes look normal early on. I thought there was just a little bit of disc edema (abnormal fluid accumulation). Her left eye visual fields (the area in which objects are seen peripherally) were normal, and both eye movements were normal. Importantly, in both eyes the pupils were equal and reactive with no afferent pupillary defect (a reduced light response by the pupil that usually results from an optic nerve lesion). The remainder of the neurological examination was normal.
Hmm. This was curious, especially the lack of an afferent pupillary defect - normally, a most reliable sign in the presence of pathology.
I sent off some blood tests. The routine blood tests for blood cell counts and electrolyte levels came back as normal. I wanted to assess for any evidence of inflammation (redness and swelling) within the body, as well as rule out vasculitis (an infective or immune-mediated destructive condition affecting blood vessels) and neuromyelitis optica (a condition involving inflammation and myelin loss within the optic nerves and spinal cord). To assess for inflammation in general, I ordered a C-reactive protein (a non-specific marker of inflammation) level, which was a bit high at 15 mg/L (lower than 10 mg/L is normal). To assess for vasculitis, I ordered antinuclear antibodies (antibodies produced by the immune system that attack one's own cells) and as part of the workup for neuromyelitis optica, I ordered aquaporin 4 antibodies (antibodies that target aquaporin 4, a cell membrane protein involved in water transport in and out of the cell). Both of the antibody tests came back negative.
Call me hard to please, but I was not at all satisfied with a smidgen of disc edema and a slightly elevated C-reactive protein level. Thus, I proceeded to perform a lumbar puncture (inserting a needle into the lower back to obtain cerebrospinal fluid) on our receptionist. I viewed the results a few hours later - it was, of course, normal.
The excess of normality here was beginning to vex me. However, I was not out of ammunition yet. I still had one more test up my sleeve - visual evoked responses (VERs). VERs record the stimulated electrical activity from the visual cortex. For this test, the patient is placed in a chair and visual stimulation is displayed on a monitor, usually in the form of a shifting checkerboard pattern or a series of flashes. Visual signals sent from the retina through the optic nerve and thalamus to the visual cortex and back are recorded from electrodes place along the scalp. VERs thus assess the functional integrity of the visual pathways, and can pick up subtle lesions that may be missed by imaging - even MRI scans.
First, the left eye:
Regardless, these events did prompt our receptionist to visit an ophthalmologist that afternoon, who could not observe any right eye pathology. The retina (the light-sensitive layer of tissue lining the inner surface of the eye) appeared healthy, as did the optic disc (the beginning of the optic nerve which carries visual information from the retina to the brain). He ordered a magnetic resonance angiogram (MRI) scan (a radiological technique that uses strong magnetic fields and radiowaves to assess the movement of water molecules within body tissues, creating an anatomical image) the next day, and the brain appeared normal. The ophthalmologist reviewed her again three days after her visual loss, and again noted no obvious right eye pathology. The ophthalmologist was decidedly stumped, and referred his half-blind patient to our hospital.
Being on ward service, I wandered over to see our newest arrival. I noted that our receptionist was a young lady of European ancestry and an average build. She was a little shaken up by what had happened, but appeared to be well in control of her emotions. Noting the recent events, I pressed on with more history. She had polycystic ovarian syndrome (a not entirely understood condition that affects young women and is associated with menstrual disorders, infertility, high levels of masculinizing hormones, and insulin resistance) and suffered from frequent headaches on most days of the week. She did not smoke, drink alcohol, or use illicit drugs, and claimed to be under no current personal or financial stress. There was no family history of vision loss, and she took no regular medications (not even the oral contraceptive pill) and had no drug allergies.
On examination, our receptionist was alert and aware. The visual acuity in her left eye was normal, but with her right eye she could perceive only bright light shined directly onto the eye - no more. I brought out my faithful ophthalmoscope (a device that allows one to see the internal eye structures) and took a closer look at her optic disc. Although the ophthalmologist had noted it to be normal a few days before, pathology can sometimes look normal early on. I thought there was just a little bit of disc edema (abnormal fluid accumulation). Her left eye visual fields (the area in which objects are seen peripherally) were normal, and both eye movements were normal. Importantly, in both eyes the pupils were equal and reactive with no afferent pupillary defect (a reduced light response by the pupil that usually results from an optic nerve lesion). The remainder of the neurological examination was normal.
Hmm. This was curious, especially the lack of an afferent pupillary defect - normally, a most reliable sign in the presence of pathology.
I sent off some blood tests. The routine blood tests for blood cell counts and electrolyte levels came back as normal. I wanted to assess for any evidence of inflammation (redness and swelling) within the body, as well as rule out vasculitis (an infective or immune-mediated destructive condition affecting blood vessels) and neuromyelitis optica (a condition involving inflammation and myelin loss within the optic nerves and spinal cord). To assess for inflammation in general, I ordered a C-reactive protein (a non-specific marker of inflammation) level, which was a bit high at 15 mg/L (lower than 10 mg/L is normal). To assess for vasculitis, I ordered antinuclear antibodies (antibodies produced by the immune system that attack one's own cells) and as part of the workup for neuromyelitis optica, I ordered aquaporin 4 antibodies (antibodies that target aquaporin 4, a cell membrane protein involved in water transport in and out of the cell). Both of the antibody tests came back negative.
Call me hard to please, but I was not at all satisfied with a smidgen of disc edema and a slightly elevated C-reactive protein level. Thus, I proceeded to perform a lumbar puncture (inserting a needle into the lower back to obtain cerebrospinal fluid) on our receptionist. I viewed the results a few hours later - it was, of course, normal.
The excess of normality here was beginning to vex me. However, I was not out of ammunition yet. I still had one more test up my sleeve - visual evoked responses (VERs). VERs record the stimulated electrical activity from the visual cortex. For this test, the patient is placed in a chair and visual stimulation is displayed on a monitor, usually in the form of a shifting checkerboard pattern or a series of flashes. Visual signals sent from the retina through the optic nerve and thalamus to the visual cortex and back are recorded from electrodes place along the scalp. VERs thus assess the functional integrity of the visual pathways, and can pick up subtle lesions that may be missed by imaging - even MRI scans.
First, the left eye:
This full field VER of the left eye is normal. The blue and yellow lines each represent two different recordings (two recordings are standard). Note the downwards "dip" in each waveform - this is the P100 wave. The most important feature to note in any VER is the P100 latency (the time it takes for the P100 wave to appear; in our lab, the P100 latency of our receptionist should be <112 ms). The P100 latency here is 94.5 ms, well within normal range. The next most important feature to note is the interocular P100 amplitude (the size of the wave; the P100 amplitude difference between each eye should be no greater than 50%). The P100 amplitude here is 7.6 uV.
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This central field VER of the left eye is also normal. The P100 latency is 97.5 ms and the P100 amplitude is 11.3 uV. Unlike a full field VER, which assesses visual signals from a large stimulus and hence a wider visual field, a central field VER assesses visual signals from a much smaller stimulus and hence only a smaller central field. For the same eye, the full field VER may be normal and the central field VER abnormal - and vice versa - if there is a particularly small area of latency delay, which in turn is suggestive of a tiny lesion involving only part of the visual tract from retina to visual cortex.
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Now, the right eye:
This full field VER of the right eye is normal. The P100 latency here is 93.5 ms, normal. The P100 amplitude is 8.0 uV, almost identical to the full field VER of the left eye.
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Alas, this central field VER of the right eye is abnormal. It should be similar to the central field VER of the left eye above, but the right eye has no P100 wave at all.
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Miraculously, one of our investigations was showing us useful information. Summing up our clues thus far, we had a little bit of right eye disc edema, a mildly raised C-reactive protein, and absent P100 waves in the right eye central field VER. Taken together, the combination was now pointing towards a mild right eye optic neuritis (inflammation of the optic nerve). This had to be taken seriously, as the most common etiology of optic neuritis is ultimately multiple sclerosis (an inflammatory condition in which the myelin - the insulating covers of neurons in the brain and spinal cord - is damaged). Since multiple sclerosis can involve demyelinating lesions anywhere within the brain, we repeated the MRI scan of the brain and asked our esteemed neuroradiologist to have a look. On this MRI, he concluded that there was probable signal change in the right optic nerve. It was not a slam-dunk though; he was not sure.
There was one other condition that had to be considered here - Leber's Hereditary Optic Neuropathy (LHON). This condition is a disorder of mitochondria (tiny organelles within cells that generate energy). It is extremely rare, usually affects young men, and is only transmitted through the mother's side. It classically results in central vision loss. However, we had no family history of visual loss. Nonetheless, I sent off a blood test to check for some of the more common mutations that can result in LHON.
None of this quite added up. The clinical deficit - total blindness in one eye - was way our of proportion to the deficit that one might have expected to see from what appeared to be an extremely mild right eye optic neuritis. Blindness ought to have been accompanied by a grossly abnormal eye examination, with a massively inflamed optic disc and a raging afferent pupillary defect, neither of which we had.
We repeated the VERs a few days after the first set.
First, the left eye:
There was one other condition that had to be considered here - Leber's Hereditary Optic Neuropathy (LHON). This condition is a disorder of mitochondria (tiny organelles within cells that generate energy). It is extremely rare, usually affects young men, and is only transmitted through the mother's side. It classically results in central vision loss. However, we had no family history of visual loss. Nonetheless, I sent off a blood test to check for some of the more common mutations that can result in LHON.
None of this quite added up. The clinical deficit - total blindness in one eye - was way our of proportion to the deficit that one might have expected to see from what appeared to be an extremely mild right eye optic neuritis. Blindness ought to have been accompanied by a grossly abnormal eye examination, with a massively inflamed optic disc and a raging afferent pupillary defect, neither of which we had.
We repeated the VERs a few days after the first set.
First, the left eye:
The full field VER of the left eye remains normal. In particular, the P100 latency is 99.8 ms, similar to what it was a few day before. The P100 amplitude is 13.9 uV.
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The central field VER of the left eye is also normal. The P100 latency is 96.6 ms and the P100 amplitude is 10.5 uV, both similar to previous.
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Now, the right eye:
The full field VER of the right eye is still within normal limits, although the P100 latency has increased to 108.5 ms (still <112 ms so in the normal range, but a few days before it was 93.5 ms). The P100 amplitude is 7.7 uV, similar to previous.
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The central field VER of the right eye remains highly abnormal, with no identifiable P100 wave.
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The persisting abnormalities in the right eye central field continued to support a diagnosis of mild right eye optic neuritis.
Strikingly, our receptionist remained reasonably calm despite her predicament. In fact, she had remained much calmer than one might reasonably expect considering the ongoing saga with her vision. It was at this point that our social worker helped us by providing some crucial additional information - after several lengthy chats, our receptionist admitted that she had suffered an emotionally traumatic event while overseas several months prior, and there was every reason to believe that she had not fully recovered from the experience. This could explain the magnitude of the visual deficit noted, which was far out of proportion to the mild right optic neuritis we had found, by the contribution of a non-organic component to the visual loss in the setting of an abnormally emotionally stressful event.
We had no other diagnosis to turn to - we diagnosed our curious receptionist with mild right optic neuritis combined with non-organic visual loss, possibly triggered by the emotional trauma and stress of her overseas experience.
Strikingly, our receptionist remained reasonably calm despite her predicament. In fact, she had remained much calmer than one might reasonably expect considering the ongoing saga with her vision. It was at this point that our social worker helped us by providing some crucial additional information - after several lengthy chats, our receptionist admitted that she had suffered an emotionally traumatic event while overseas several months prior, and there was every reason to believe that she had not fully recovered from the experience. This could explain the magnitude of the visual deficit noted, which was far out of proportion to the mild right optic neuritis we had found, by the contribution of a non-organic component to the visual loss in the setting of an abnormally emotionally stressful event.
We had no other diagnosis to turn to - we diagnosed our curious receptionist with mild right optic neuritis combined with non-organic visual loss, possibly triggered by the emotional trauma and stress of her overseas experience.
The Condition
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Optic neuritis is optic nerve inflammation that may result in an acute partial or complete loss of vision in the affected eye. It often indicates an underlying disease process such as multiple sclerosis or neuromyelitis optica. If optic neuritis is diagnosed, corticosteroid treatment with intravenous methylprednisolone (a powerful steroid that reduces inflammation) is usually given, although this may not affect the long-term outcome in cases where the optic neuritis is secondary to multiple sclerosis (Beck et al, 1993).
Non-organic visual loss is visual loss without evidence of pathology, and includes psychogenic (not fabricated) as well as malingering (fabricated or exaggerated) visual loss. Non-organic visual loss represents 1 to 5% of visual problems seen by ophthalmologists and is more common among younger females (Toldo et al, 2010). A stressful event - usually family or psychological problems - precedes the diagnosis in over 80% of cases (Toldo et al, 2010). Investigative tests, such as MRI scans and VERs, are usually normal. In psychogenic visual loss, visual loss responds best to empathic concern, explaining that the disorder lacks any known organic pathology, and a frank admission that psychogenic disorders are not well understood. It is important to realize that the visual loss is not fabricated by the patient; the symptoms are real, even with the lack of an identifiable structural abnormality. More than anything, the mainstay of treatment is reassurance that a full visual recovery is expected. Psychiatric referral is not considered necessary. Eventually, 93% of patients with psychogenic visual loss will show complete recovery (Toldo et al, 2010). |
Normal optic disc (the beginning of the optic nerve at the back of the eye). The borders are sharply demarcated and the colour is pinkish orange.
Papilledema of the optic disc, which occurs in optic neuritis. The borders are obscured and the colour is pale.
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Epilogue
We initiated treatment for our receptionist the same day she was admitted with five days of intravenous methylprednisolone. After a couple of weeks in hospital her vision had improved to the point where she could detect movement in front of her and so she was discharged with outpatient followup. She had a repeat MRI brain with dedicated views of the orbits, but it remained normal. Her vision fluctuated somewhat over the next few weeks, sometimes better, sometimes worse, a clinical picture quite consistent with non-organic visual loss. Moreover, the blood tests that we had sent to assess for common LHON mutations came back negative.
Unfortunately, I lost touch with our curious receptionist. I hope that her vision returned.
Just one of those cases that keeps you humble.
Unfortunately, I lost touch with our curious receptionist. I hope that her vision returned.
Just one of those cases that keeps you humble.
References
Beck et al. 1993. The effect of corticosteroids for acute optic neuritis on the subsequent development of multiple sclerosis. New England Journal of Medicine 329, 1764-1769.
Toldo et al. 2010. Nonorganic (psychogenic) visual loss in children: a retrospective series. Journal of Neuro-ophthalmology 30(1), 26-30.
Beck et al. 1993. The effect of corticosteroids for acute optic neuritis on the subsequent development of multiple sclerosis. New England Journal of Medicine 329, 1764-1769.
Toldo et al. 2010. Nonorganic (psychogenic) visual loss in children: a retrospective series. Journal of Neuro-ophthalmology 30(1), 26-30.
