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Visual Loss in a 42-Year-Old Man
SURVEY OF OPHTHALMOLOGY VOLUME 44 • NUMBER 6 • MAY–JUNE 2000
CLINICAL CHALLENGES PETER SAVINO, EDITOR
Visual Loss in a 42-Year-Old Man Suzanne K. Freitag, MD, and Neil R. Miller, MD Division of Neuro-Ophthalmology and Orbital Disease, Johns Hopkins University, Wilmer Eye Institute, Baltimore, Maryland, USA
Comments by Gregory Kosmorsky, DO (In keeping with the format of a clinical pathological conference, the abstract and key words appear at the end of the article.)
Case Report: A 42-year-old man complained of blurred vision of 3 months’ duration, worse in the right eye (OD) than in the left eye (OS). He was examined by an ophthalmologist, who found normal acuity in both eyes (OU) and an abnormal visual field in the right eye by automated perimetry. The patient was referred for neuro-ophthalmology consultation. His medical history was unremarkable. On examination, Snellen visual acuity was 20/20 OU. The patient correctly identified 10 of 10 Hardy-Rand-Rittler color plates with both eyes. Both pupils were briskly reactive, but there was a right relative afferent pupillary defect. The patient was orthophoric in all fields of gaze. Results of slit-lamp examination were normal bilaterally, and intraocular pressure was 17 mm Hg OU. Corneal and facial sensation were intact bilaterally. Dilated funduscopic examination revealed normal optic disks, vessels, maculae, and peripheral retinas in both eyes. Results of kinetic and static perimetry are shown in Figs. 1 and 2. A magnetic resonance image (MRI) was obtained (Fig. 3), a diagnosis of pituitary adenoma was made, and the patient was scheduled for transsphenoidal removal of the lesion.
What is the most likely diagnosis? Do you agree with the planned treatment?
Discussion Comments of Gregory S. Kosmorsky, DO, Cleveland Clinic Foundation, Cole Eye Institute, Cleveland, Ohio, USA The patient is a young man who has blurred vision in both eyes and whose MRI suggests a diagnosis of pituitary adenoma. The patient, therefore, was scheduled for transsphenoidal removal of the tumor. As part of the preoperative assessment, the patient was referred for a complete neuro-ophthalmologic examination, which demonstrated a right inferior congruous hemianopic defect. This finding suggests that the lesion is affecting the left optic tract and, in particular, the superior fibers of the tract. This, in turn, suggests that the lesion is likely superior to the tract, rather than inferior to it, as would be expected with a pituitary tumor. The most frequent cause of an optic tract syndrome is craniopharyngioma and not a pituitary tumor. I would alert the neurosurgeon that the lesion is not likely to be a pituitary adenoma and that a craniotomy, rather than a transsphenoidal procedure, should be considered.
Based on the results of the examination, where exactly is the damage to the visual system? 507 © 2000 by Elsevier Science Inc. All rights reserved.
0039-6257/00/$–see front matter PII S0039-6257(00)00113-2
508
Surv Ophthalmol 44 (6) May–June 2000
FREITAG AND MILLER
Fig. 1. Results of kinetic perimetry. Left: Left eye. Right: Right eye.
Before addressing the significance of the visual field defect, we need to point out that a diagnosis of pituitary tumor in this case is unlikely, based on the MRI findings. The enhanced T1 sagittal image that is provided clearly shows an inhomogeneous mass. Pituitary tumors usually have a uniform appearance on MRI. They are isointense on T1- and T2-weighted images and usually diffusely enhance after intravenous injection with gadolinium-DTPA or a similar paramagnetic substance.1 Thus, although the lesion in this case clearly occupies the sella turcica, it is more likely to be a craniopharyngioma, germinoma, or dermoid. Nevertheless, it is the location of the damage to the anterior visual system that provides the most telling evidence that the tumor is not a pituitary adenoma. Because of their location, pituitary tumors that are large enough to cause a visual sensory disturbance usually cause some type of optic chiasmal syndrome. The anterior chiasmal syndrome consists of a unilateral optic neuropathy associated with a superior temporal defect in the contralateral eye. This is said to result from damage to the fibers that occupy socalled Wilbrand’s knee. These fibers originate from ganglion cells that are inferior and nasal to the fovea of the contralateral eye. The fibers cross in the chiasm and are said to then arch forward a millimeter or two into the distal portion of the opposite optic nerve. Thus, if an optic nerve is injured at its junction with the optic chiasm, the damage causes an ipsilateral optic neuropathy and a contralateral superior temporal visual field defect.4 Although there is both anatomic2 and clinical3 evidence that Wilbrand’s knee may not exist; i.e., that fibers from one optic nerve do not arch forward into the distal seg-
ment of the opposite optic nerve, the anterior chiasmal syndrome is a true clinical entity.4 The syndrome of the body of the chiasm consists of a complete or incomplete bitemporal hemianopia. When the hemianopia is incomplete, it is usually denser above, reflecting damage to the inferior fibers of the chiasm from the suprasellar but infrachiasmatic location of the pituitary tumor.1 Finally, the posterior chiasmal syndrome consists of bitemporal hemianopic scotomas, with preservation of normal visual acuity and color vision.4 This syndrome is said to occur because the majority of fibers subserving the macula occupy the posterior aspect of the optic chiasm. Thus, lesions that damage the nasal fibers that cross in the posterior chiasm spare the peripheral temporal visual fields. Only about 5% of patients with visual sensory defects from a pituitary adenoma have evidence of damage to the optic tract.1 In such cases, the patient may have a so-called prefixed chiasm, in which the intracranial portion of the optic nerve is so short that upward expansion of the tumor compresses one optic tract rather than a portion of the optic chiasm.7 Alternatively, the tumor may have expanded posteriorly, thus damaging the optic tract rather than the optic chiasm. In either case, damage to the optic tract may produce a complete or incomplete homonymous hemianopia. When the hemianopia is incomplete, it is typically incongruous and often scotomatous. Indeed, the optic tract is said to be the only location other than the occipital lobe in which damage can produce a scotomatous homonymous defect.4 The explanation for the tendency of lesions of the optic tract to produce incongruous hemianopic defects is somewhat controversial. It was
VISUAL LOSS IN A 42-YEAR-OLD MAN
Fig. 2. Results of static perimetry. Top: Left eye. Bottom: Right eye.
509
510
Surv Ophthalmol 44 (6) May–June 2000
Fig. 3. Sagittal T1-weighted MRI of the brain showing an intrasellar and suprasellar mass (arrow).
thought that there was a laminated segregation of fibers throughout the anterior visual sensory pathway, such that fibers subserving the peripheral visual field were located peripherally, whereas fibers subserving the central visual field were located centrally within the optic nerves, chiasm, and tracts. Thus, lesions that damage the peripheral aspects of the optic tract would be expected to affect the peripheral but not the central field, whereas lesions that damage the
FREITAG AND MILLER
central portion of the tract would be expected to cause central field defects. It was also believed that, after crossing in the chiasm, fibers from corresponding points in the retinas of the two eyes gradually came closer together within the tracts. In fact, anatomic studies in both cats and monkeys demonstrate that large axons, whether they originate from the peripheral or central retina, tend to occupy the peripheral aspects of the optic tract, whereas smaller axons, regardless of their point of origin in the retina, occupy the center of the tract.5,6 Thus, there is a diffuse representation of the visual field in both the central and peripheral portions of the optic tract, and regardless of the region of the tract damaged, a diffuse field defect is likely to be produced. This may explain the widely varying types of field defects observed in patients with optic tract damage and the tendency for such defects to be incongruous. The incongruous nature of the defect in this case points to damage to the optic tract, and although this would be an unusual deficit for a pituitary tumor to produce, one cannot exclude the diagnosis on this basis alone. In fact, the most important aspect of the visual field defect in this case is not its homonymous nature, but the fact that it is denser below than above. This suggests damage to the superior tract fibers rather than to inferior tract fibers, as would be expected from a lesion arising from below the optic chiasm and optic tracts. Projections from the retina through the optic nerves, chiasm, and tracts are such that fibers that subserve the superior aspect of the vi-
Fig. 4. Hematoxylin and eosin–stained histopathologic section of tumor showing stratified squamous epithelium, vascular connective-tissue stroma, and a cyst containing degenerating epithelial cells and keratin consistent with craniopharyngioma (⫻600).
VISUAL LOSS IN A 42-YEAR-OLD MAN
511
Fig. 5. Static perimetry performed on postoperative day 5 shows marked improvement of the right visual field defect. Top: Left eye. Bottom: Right eye.
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Surv Ophthalmol 44 (6) May–June 2000
sual field are located in the inferior retina, inferior portion of the optic nerves, inferior portion of the optic chiasm, and inferior aspects of the optic tracts, whereas fibers that subserve the inferior aspect of the visual field are located in the superior retina, superior portion of the optic nerves, superior portion of the optic chiasm, and superior aspects of the optic tracts.4 Seeing this defect, I believe the lesion causing the defect is damaging the superior aspect of the optic tract. It would be extremely unusual for this to result from compression by a suprasellar, infrachiasmatic process, such as a pituitary adenoma. Thus, I suspect a suprasellar, suprachiasmatic process, such as a craniopharyngioma, meningioma, or germinoma, and I would recommend that the neurosurgeon consider a craniotomy, rather than a transsphenoidal procedure, to identify and treat the lesion.
Case Report (Conclusion) After we reviewed the patient’s visual fields, it was our opinion that the diagnosis of pituitary adenoma was unlikely. The patient had an obvious left optic tract syndrome, producing a right-sided incongruous homonymous hemianopia. Pituitary tumors can produce a tract syndrome from either posterior growth or a prefixed chiasm. However, the visual field loss was more dense inferiorly, which suggests damage to the superior fibers of the chiasm. It would be very unlikely that a primary pituitary mass, growing up from below the chiasm, would damage the superior chiasmal fibers. Thus, other tumors were considered more likely than pituitary adenoma in the differential diagnosis, particularly craniophar-
FREITAG AND MILLER
yngioma, meningioma, or germinoma. The patient and neurosurgeon were informed of this opinion, after which the neurosurgeon changed the surgical approach from transsphenoidal to craniotomy. Several days later, the patient underwent uneventful resection of the mass, of which the pathologic findings showed a craniopharyngioma (Fig. 4). On postoperative day 5, the patient’s visual acuity was 20/20 OU and results of color plate testing were 10 of 10 OU. Repeat static perimetry at that time showed improvement of the visual field defect in both eyes (Fig. 5).
References 1. Gittinger JW Jr: Pituitary tumors, in Miller NR, Newman NJ (eds): Walsh and Hoyt’s Clinical Neuro-Ophthalmology, Vol 2. Baltimore, Williams & Wilkins, 1998, ed 5, p 2141 2. Horton JC: Wilbrand’s knee of the primate optic chiasm is an artefact of monocular enucleation. Trans Am Ophthalmol Soc 95:579–609, 1997 3. Kosmorsky GS: Human verification of the mythical knee of Wilbrand. Presented at the North American Neuro-Ophthalmology Society Meeting, Snowmass, Colorado, March 14–18, 1999. 4. Miller NR, Newman NJ: Topical diagnosis of lesions in the visual sensory pathway, in Miller NR, Newman NJ (eds): Walsh and Hoyt’s Clinical Neuro-Ophthalmology, Vol 1. Baltimore, Williams & Wilkins, 1998, ed 5, pp 237–38 5. Reese BE, Guillery RW: Distribution of axons according to diameter in the monkey’s optic tract. J Comp Neurol 206:453– 60, 1987 6. Reese B, Guillery RW, Marzi CA, Tassinari G: Position of axons in the cat’s optic tract in relation to their retinal origin and chiasmatic pathway. J Comp Neurol 306:539–553, 1991 7. Slamovits TL: Anatomy and physiology of the optic chiasm, in Miller NR, Newman NJ (eds): Walsh and Hoyt’s Clinical Neuro-Ophthalmology, Vol 1. Baltimore, Williams & Wilkins, 1998, ed 5, pp 85–100
Reprints are not available.
Abstract. A 42-year-old man developed blurred vision and was found to have a right, incongruous, inferior homonymous quadrantanopia. Neuroimaging disclosed a suprasellar mass. The mass was thought to be a pituitary adenoma that was compressing the left optic tract, and transsphenoidal surgery was planned; however, because the defect was primarily inferior, indicating damage to the superior aspect of the optic tract, it was recommended that a craniotomy be performed. The mass was found at surgery to be a craniopharyngioma. (Surv Ophthalmol 44:507–512, 2000. © 2000 by Elsevier Science Inc. All rights reserved.) Key words. craniopharyngioma • homonymous quadrantanopia • optic tract
CLINICAL CHALLENGES PETER SAVINO, EDITOR
Visual Loss in a 42-Year-Old Man Suzanne K. Freitag, MD, and Neil R. Miller, MD Division of Neuro-Ophthalmology and Orbital Disease, Johns Hopkins University, Wilmer Eye Institute, Baltimore, Maryland, USA
Comments by Gregory Kosmorsky, DO (In keeping with the format of a clinical pathological conference, the abstract and key words appear at the end of the article.)
Case Report: A 42-year-old man complained of blurred vision of 3 months’ duration, worse in the right eye (OD) than in the left eye (OS). He was examined by an ophthalmologist, who found normal acuity in both eyes (OU) and an abnormal visual field in the right eye by automated perimetry. The patient was referred for neuro-ophthalmology consultation. His medical history was unremarkable. On examination, Snellen visual acuity was 20/20 OU. The patient correctly identified 10 of 10 Hardy-Rand-Rittler color plates with both eyes. Both pupils were briskly reactive, but there was a right relative afferent pupillary defect. The patient was orthophoric in all fields of gaze. Results of slit-lamp examination were normal bilaterally, and intraocular pressure was 17 mm Hg OU. Corneal and facial sensation were intact bilaterally. Dilated funduscopic examination revealed normal optic disks, vessels, maculae, and peripheral retinas in both eyes. Results of kinetic and static perimetry are shown in Figs. 1 and 2. A magnetic resonance image (MRI) was obtained (Fig. 3), a diagnosis of pituitary adenoma was made, and the patient was scheduled for transsphenoidal removal of the lesion.
What is the most likely diagnosis? Do you agree with the planned treatment?
Discussion Comments of Gregory S. Kosmorsky, DO, Cleveland Clinic Foundation, Cole Eye Institute, Cleveland, Ohio, USA The patient is a young man who has blurred vision in both eyes and whose MRI suggests a diagnosis of pituitary adenoma. The patient, therefore, was scheduled for transsphenoidal removal of the tumor. As part of the preoperative assessment, the patient was referred for a complete neuro-ophthalmologic examination, which demonstrated a right inferior congruous hemianopic defect. This finding suggests that the lesion is affecting the left optic tract and, in particular, the superior fibers of the tract. This, in turn, suggests that the lesion is likely superior to the tract, rather than inferior to it, as would be expected with a pituitary tumor. The most frequent cause of an optic tract syndrome is craniopharyngioma and not a pituitary tumor. I would alert the neurosurgeon that the lesion is not likely to be a pituitary adenoma and that a craniotomy, rather than a transsphenoidal procedure, should be considered.
Based on the results of the examination, where exactly is the damage to the visual system? 507 © 2000 by Elsevier Science Inc. All rights reserved.
0039-6257/00/$–see front matter PII S0039-6257(00)00113-2
508
Surv Ophthalmol 44 (6) May–June 2000
FREITAG AND MILLER
Fig. 1. Results of kinetic perimetry. Left: Left eye. Right: Right eye.
Before addressing the significance of the visual field defect, we need to point out that a diagnosis of pituitary tumor in this case is unlikely, based on the MRI findings. The enhanced T1 sagittal image that is provided clearly shows an inhomogeneous mass. Pituitary tumors usually have a uniform appearance on MRI. They are isointense on T1- and T2-weighted images and usually diffusely enhance after intravenous injection with gadolinium-DTPA or a similar paramagnetic substance.1 Thus, although the lesion in this case clearly occupies the sella turcica, it is more likely to be a craniopharyngioma, germinoma, or dermoid. Nevertheless, it is the location of the damage to the anterior visual system that provides the most telling evidence that the tumor is not a pituitary adenoma. Because of their location, pituitary tumors that are large enough to cause a visual sensory disturbance usually cause some type of optic chiasmal syndrome. The anterior chiasmal syndrome consists of a unilateral optic neuropathy associated with a superior temporal defect in the contralateral eye. This is said to result from damage to the fibers that occupy socalled Wilbrand’s knee. These fibers originate from ganglion cells that are inferior and nasal to the fovea of the contralateral eye. The fibers cross in the chiasm and are said to then arch forward a millimeter or two into the distal portion of the opposite optic nerve. Thus, if an optic nerve is injured at its junction with the optic chiasm, the damage causes an ipsilateral optic neuropathy and a contralateral superior temporal visual field defect.4 Although there is both anatomic2 and clinical3 evidence that Wilbrand’s knee may not exist; i.e., that fibers from one optic nerve do not arch forward into the distal seg-
ment of the opposite optic nerve, the anterior chiasmal syndrome is a true clinical entity.4 The syndrome of the body of the chiasm consists of a complete or incomplete bitemporal hemianopia. When the hemianopia is incomplete, it is usually denser above, reflecting damage to the inferior fibers of the chiasm from the suprasellar but infrachiasmatic location of the pituitary tumor.1 Finally, the posterior chiasmal syndrome consists of bitemporal hemianopic scotomas, with preservation of normal visual acuity and color vision.4 This syndrome is said to occur because the majority of fibers subserving the macula occupy the posterior aspect of the optic chiasm. Thus, lesions that damage the nasal fibers that cross in the posterior chiasm spare the peripheral temporal visual fields. Only about 5% of patients with visual sensory defects from a pituitary adenoma have evidence of damage to the optic tract.1 In such cases, the patient may have a so-called prefixed chiasm, in which the intracranial portion of the optic nerve is so short that upward expansion of the tumor compresses one optic tract rather than a portion of the optic chiasm.7 Alternatively, the tumor may have expanded posteriorly, thus damaging the optic tract rather than the optic chiasm. In either case, damage to the optic tract may produce a complete or incomplete homonymous hemianopia. When the hemianopia is incomplete, it is typically incongruous and often scotomatous. Indeed, the optic tract is said to be the only location other than the occipital lobe in which damage can produce a scotomatous homonymous defect.4 The explanation for the tendency of lesions of the optic tract to produce incongruous hemianopic defects is somewhat controversial. It was
VISUAL LOSS IN A 42-YEAR-OLD MAN
Fig. 2. Results of static perimetry. Top: Left eye. Bottom: Right eye.
509
510
Surv Ophthalmol 44 (6) May–June 2000
Fig. 3. Sagittal T1-weighted MRI of the brain showing an intrasellar and suprasellar mass (arrow).
thought that there was a laminated segregation of fibers throughout the anterior visual sensory pathway, such that fibers subserving the peripheral visual field were located peripherally, whereas fibers subserving the central visual field were located centrally within the optic nerves, chiasm, and tracts. Thus, lesions that damage the peripheral aspects of the optic tract would be expected to affect the peripheral but not the central field, whereas lesions that damage the
FREITAG AND MILLER
central portion of the tract would be expected to cause central field defects. It was also believed that, after crossing in the chiasm, fibers from corresponding points in the retinas of the two eyes gradually came closer together within the tracts. In fact, anatomic studies in both cats and monkeys demonstrate that large axons, whether they originate from the peripheral or central retina, tend to occupy the peripheral aspects of the optic tract, whereas smaller axons, regardless of their point of origin in the retina, occupy the center of the tract.5,6 Thus, there is a diffuse representation of the visual field in both the central and peripheral portions of the optic tract, and regardless of the region of the tract damaged, a diffuse field defect is likely to be produced. This may explain the widely varying types of field defects observed in patients with optic tract damage and the tendency for such defects to be incongruous. The incongruous nature of the defect in this case points to damage to the optic tract, and although this would be an unusual deficit for a pituitary tumor to produce, one cannot exclude the diagnosis on this basis alone. In fact, the most important aspect of the visual field defect in this case is not its homonymous nature, but the fact that it is denser below than above. This suggests damage to the superior tract fibers rather than to inferior tract fibers, as would be expected from a lesion arising from below the optic chiasm and optic tracts. Projections from the retina through the optic nerves, chiasm, and tracts are such that fibers that subserve the superior aspect of the vi-
Fig. 4. Hematoxylin and eosin–stained histopathologic section of tumor showing stratified squamous epithelium, vascular connective-tissue stroma, and a cyst containing degenerating epithelial cells and keratin consistent with craniopharyngioma (⫻600).
VISUAL LOSS IN A 42-YEAR-OLD MAN
511
Fig. 5. Static perimetry performed on postoperative day 5 shows marked improvement of the right visual field defect. Top: Left eye. Bottom: Right eye.
512
Surv Ophthalmol 44 (6) May–June 2000
sual field are located in the inferior retina, inferior portion of the optic nerves, inferior portion of the optic chiasm, and inferior aspects of the optic tracts, whereas fibers that subserve the inferior aspect of the visual field are located in the superior retina, superior portion of the optic nerves, superior portion of the optic chiasm, and superior aspects of the optic tracts.4 Seeing this defect, I believe the lesion causing the defect is damaging the superior aspect of the optic tract. It would be extremely unusual for this to result from compression by a suprasellar, infrachiasmatic process, such as a pituitary adenoma. Thus, I suspect a suprasellar, suprachiasmatic process, such as a craniopharyngioma, meningioma, or germinoma, and I would recommend that the neurosurgeon consider a craniotomy, rather than a transsphenoidal procedure, to identify and treat the lesion.
Case Report (Conclusion) After we reviewed the patient’s visual fields, it was our opinion that the diagnosis of pituitary adenoma was unlikely. The patient had an obvious left optic tract syndrome, producing a right-sided incongruous homonymous hemianopia. Pituitary tumors can produce a tract syndrome from either posterior growth or a prefixed chiasm. However, the visual field loss was more dense inferiorly, which suggests damage to the superior fibers of the chiasm. It would be very unlikely that a primary pituitary mass, growing up from below the chiasm, would damage the superior chiasmal fibers. Thus, other tumors were considered more likely than pituitary adenoma in the differential diagnosis, particularly craniophar-
FREITAG AND MILLER
yngioma, meningioma, or germinoma. The patient and neurosurgeon were informed of this opinion, after which the neurosurgeon changed the surgical approach from transsphenoidal to craniotomy. Several days later, the patient underwent uneventful resection of the mass, of which the pathologic findings showed a craniopharyngioma (Fig. 4). On postoperative day 5, the patient’s visual acuity was 20/20 OU and results of color plate testing were 10 of 10 OU. Repeat static perimetry at that time showed improvement of the visual field defect in both eyes (Fig. 5).
References 1. Gittinger JW Jr: Pituitary tumors, in Miller NR, Newman NJ (eds): Walsh and Hoyt’s Clinical Neuro-Ophthalmology, Vol 2. Baltimore, Williams & Wilkins, 1998, ed 5, p 2141 2. Horton JC: Wilbrand’s knee of the primate optic chiasm is an artefact of monocular enucleation. Trans Am Ophthalmol Soc 95:579–609, 1997 3. Kosmorsky GS: Human verification of the mythical knee of Wilbrand. Presented at the North American Neuro-Ophthalmology Society Meeting, Snowmass, Colorado, March 14–18, 1999. 4. Miller NR, Newman NJ: Topical diagnosis of lesions in the visual sensory pathway, in Miller NR, Newman NJ (eds): Walsh and Hoyt’s Clinical Neuro-Ophthalmology, Vol 1. Baltimore, Williams & Wilkins, 1998, ed 5, pp 237–38 5. Reese BE, Guillery RW: Distribution of axons according to diameter in the monkey’s optic tract. J Comp Neurol 206:453– 60, 1987 6. Reese B, Guillery RW, Marzi CA, Tassinari G: Position of axons in the cat’s optic tract in relation to their retinal origin and chiasmatic pathway. J Comp Neurol 306:539–553, 1991 7. Slamovits TL: Anatomy and physiology of the optic chiasm, in Miller NR, Newman NJ (eds): Walsh and Hoyt’s Clinical Neuro-Ophthalmology, Vol 1. Baltimore, Williams & Wilkins, 1998, ed 5, pp 85–100
Reprints are not available.
Abstract. A 42-year-old man developed blurred vision and was found to have a right, incongruous, inferior homonymous quadrantanopia. Neuroimaging disclosed a suprasellar mass. The mass was thought to be a pituitary adenoma that was compressing the left optic tract, and transsphenoidal surgery was planned; however, because the defect was primarily inferior, indicating damage to the superior aspect of the optic tract, it was recommended that a craniotomy be performed. The mass was found at surgery to be a craniopharyngioma. (Surv Ophthalmol 44:507–512, 2000. © 2000 by Elsevier Science Inc. All rights reserved.) Key words. craniopharyngioma • homonymous quadrantanopia • optic tract