A 44-year-old left-handed woman presented with a history of headache. Neurological examination revealed left hand incoordination. Imaging on a 1.5-T imager (Magnetom® Vision, Siemens, Erlangen, Germany) with T1, T2 and T1 post-gadolinium (Magnevist, Berlex Laboratories, Wayne, NJ) weighting depicted a large 4 cm x 3.5 cm x 3.5 cm enhancing right temporoparietal mass with surrounding edema. The patient had a subtotal resection due to the proximity of the lesion to the Sylvian fissure and to the motor cortex.
Prepared by James M. Larner, MD, and Charles H. Shelton III,
MD, Department of Therapeutic Radiology and Oncology; Mark E.
Shaffrey, MD, Department of Neurosurgery; Steven A. Newman, MD,
Department of Opthamology; and C. Douglas Phillips, MD,
Department of Radiology, University of Virginia Medical Center,
Charlottesville, VA. Dr. Phillips is also a member of the
editorial advisory board of this journal.
A 44-year-old left-handed woman presented with a history of
headache. Neurological examination revealed left hand
incoordination. Imaging on a 1.5-T imager (Magnetom
Vision, Siemens, Erlangen, Germany) with T1, T2 and T1
post-gadolinium (Magnevist, Berlex Laboratories, Wayne, NJ)
weighting depicted a large 4 cm x 3.5 cm x 3.5 cm enhancing right
temporoparietal mass with surrounding edema. The patient had a
subtotal resection due to the proximity of the lesion to the
Sylvian fissure and to the motor cortex. What is the most likely
Glioblastoma multiforme (GBM) with infiltration along the optic
tract. Radiographic features included an inhomogeneous mass with
nodular, peripheral enhancement, and an infiltrative pattern of
growth. Lesions which could potentially be included in the
differential diagnosis are primary optic chiasmal glioma,
meningioma, abscess, and metastases.
Postoperatively, an incomplete left homonymous hemianopsia was
evident. During radiotherapy, the patient developed new onset
left-sided weakness. MR imaging demonstrated progressive disease,
and she underwent a second debulking procedure. Radiotherapy was
completed; however, following two cycles of BCNU, the patient
developed worsening left-sided paresis and a central cranial nerve
VII palsy. The ophthalmologic examination revealed a dense left
homonymous hemianopsia, a new relative left afferent pupillary
defect, and normal visual acuity but no evidence of band atrophy OS
(figure 1). MR imaging confirmed worsening disease with involvement
of the right optic tract and chiasm by tumor (figures 2,3).
Procarbazine was offered for salvage chemotherapy but the patient
continued to decline neurologically, expiring eight months from the
time of her diagnosis.
Glioblastoma multiforme and other infiltrative astrocytomas
account for the majority of adult primary CNS malignancies.
Direct involvement of the afferent pathways, such as the optic
nerve, chiasm, optic tract, lateral geniculate body, radiations,
and occipital cortex may result in focal visual loss.
Visual loss may progress slowly or be sudden in onset.
Cases of primary GBMs involving the optic pathways have been
described, although they are much less common than the childhood
benign variant of optic gliomas.
The chiasm is most frequently involved; GBMs of the optic nerve and
posterior pathways are rare.
In view of their aggressive growth, rapid progression to blindness
and death is common.
Visual symptoms are found at presentation in approximately 30%
of cases of primary brain tumors.
Visual impairment from central nervous system tumors generally can
be attributed to either local effects (mass effect, edema, or
direct infiltration) or to increased intracranial pressure.
Increased intracranial pressure itself may be due to a rapidly
expanding tumor, peritumoral edema, or to obstruction of
cerebrospinal fluid outflow.
On rare occasions, distal vascular effects can occur, either due to
local involvement of the vascular supply or related to herniation
syndrome secondary to increased intracranial pressure.
Classically, malignant astrocytomas spread along white matter
tracts. Spread of GBM along the corpus callosum results in a
"butterfly" pattern, leading to bihemispheric involvement. Other
common patterns of white matter spread include temporal lobe with
ipsilateral basal ganglia, occipital lobe with splenium of corpus
callosum, and basal ganglia with extension by way of the crus
cerebri to the mesencephalon or contralateral thalamus.
This case presents an unusual pattern of spread along the optic
tract post-chiasmatically, with evidence of continued spread to the
level of the chiasm (figures 2,3). While it is interesting to note
that the patient initially presented with no visual deficits, she
later developed a progressive homonymous hemianopsia. The initial
visual findings were consistent with reports of visual field cuts
described for temporal lobe lesions, with homonymous hemianopsia or
quadrantanopsia occurring in 67% cases.
Ultimately, the patient showed evidence of a right optic tract
syndrome, including complete left homonymous hemianopsia and a
contralateral afferent pupillary defect without any loss of visual
acuity or color vision.
The lack of optic atrophy (figure 1) is indicative of the rapid
growth of this GBM.
Magnetic resonance imaging has been demonstrated to be the
imaging modality of choice for diagnosis and demonstration of the
progression of intracranial neoplasms, including malignant gliomas
involving the visual pathways.
In particular, MR is superior in visualizing the intracanalicular
portions of the optic nerve, chiasm, hypothalamus, and optic tract
pathways due to elimination of bone artifacts and improved contrast
enhancement resulting from subtle differences in fat content and
hydration of neural tissue.