Key-words:
Craniopharyngioma - optic tract edema - pituitary macroadenoma
Introduction
Pituitary macroadenoma is a relatively common tumour of the central nervous system
(CNS) accounting for almost 15% of all primary brain tumors and almost 25% of benign
primary brain tumors.[[1]] The clinical presentation of these tumors vary depending on the functional status
of the tumors, features of hypopituitarism if the pituitary gland is involved or compressed
by the tumor and myriad of visual field defects/visual acuity disturbances depending
on the size of the tumor or degree of involvement of the visual apparatus.[[2]] Almost exclusively, the anterior visual pathway is involved by pituitary tumors
due to varying degrees of mass effect or compression of the anterior visual pathway.[[2]] Edema of the optic tract due to pituitary macroadenoma is a very rare finding on
magnetic resonance imaging (MRI) compared to craniopharyngiomas. We describe a case
of pituitary macroadenoma which was associated with bilateral optic tract edema as
demonstrated on MRI.
Case Report
A 74-year-old female known case of Type II diabetes mellitus, primary hypertension
and deep venous thrombosis (DVT) of the left leg on tablet warfarin, was admitted
to our hospital for the evaluation of upper gastrointestinal bleed. The patient had
no complaints of any visual problems before this admission and had complaints of mild
global headache on and off for the past 4–5 months. There was no history of sudden
worsening of her headache associated with visual deterioration in the past. After
5 days of admission to the hospital, the patient complaints of rapidly worsening eyesight
which was not associated with any change in the character of her headache.
Clinical and neurological evaluation revealed visual acuity of perception of hand
movement in the left eye at 3 feet distance and only perception of light in the right
eye. Pupils were bilaterally 04 mm and reacting to light. Rest of the systemic and
neurological examination was unremarkable. Perimetry for visual field defects could
not performed due to the poor visual acuity of the patient. The visual evoked potential
was not recordable. Endocrinological evaluation did not reveal any hormonal disturbances.
Multiplanar contrast enhanced MRI revealed approximately 30 mm × 25 mm × 24 mm mass
lesion in the sellar and suprasellar region. This mass lesion was seem to displace
the optic chiasm superiorly, and pituitary could not be separately visualized from
the lesion [[Figure 1]]. There was no evidence of apoplexy on the MRI. Axial fluid-attenuated inversion
recovery sequence revealed bilateral optic tract edema (right > left) [[Figure 2]]. No other abnormalities were noted on MRI.
Figure 1: T1 sagittal postcontrast image showing the pituitary macroadenoma (marked by the
arrow)
Figure 2: Axial fluid-attenuated inversion recovery image showing the edema of the optic tract
bilaterally (marked by the arrows)
In view of the rapid deterioration of the vision and MRI findings of bilateral optic
tract edema, injection dexamethasone 4 mg IV QID was started for the patient and the
patient was planned for trans nasal transsphenoidal excision of the tumor. Since the
patient had deranged international normalized ratio (2.10), she could not be taken
up for surgery immediately which carried a high risk of bleeding in the intra- and
post-operative period. After 3 days of administration of injection dexamethasone,
the patient had improvement in her vision. The patient was not willing for any surgical
intervention because of her age, comorbidities, and significant risk of bleeding in
her case because of the medications for DVT. She has been kept on follow-up for visual
complaints.
Discussion
Pituitary tumors are relatively common tumors of CNS, and there incidence reported
in literature is 15% of all primary brain tumors.[[3]] One of the modes of presentation of these tumors is a combination of various types
of visual defects as characterized in the detailed ophthalmologic evaluation. These
visual deficits are produced by pituitary macroadenomas by causing various degrees
of compression on the anterior visual apparatus mainly the optic chiasma. The visual
loss also occurs due to long-standing compression on the optic nerve leading to its
atrophy which is indirectly demonstrated on fundus examination by optic disc pallor.
MRI of the visual apparatus in pituitary macroadenoma reveals various degrees of compression
and splaying of the optic chiasma over the tumour which is the cause of visual deficits
in these patients.
However, vary rarely do we have findings in the posterior optic apparatus on imaging
in patients with pituitary adenomas. Optic tract edema as visualized on MRI is more
commonly associated with craniopharyngioma rather than pituitary macroadenoma. In
the study published by Nagahata et al.[[4]] optic tract edema was detected in five of the eight patients with craniopharyngioma,
whereas none of the patients with pituitary macroadenoma (n = 15) or tuberculum sellae
meningiomas (n = 06) revealed optic tract edema on MRI. More recently Hirunpat et
al.[[3]] in their article found optic tract edema in 7 of 11 patients with craniopharyngiomas
whereas no optic tract edema was seen 28 pituitary macroadenoma, 4 meningioma, and
similar other rarer pathologies of sellar/suprasellar regions (hypothalamic hamartoma,
germinoma, astrocytoma, and arachnoid cyst).
Optic tract edema in patients has been demonstrated on MRI the study by Saeki et al.[[5]] in which 4 out of 25 pituitary adenomas had these findings whereas 8 of 11 craniopharyngiomas
had optic tract edema. However, there was no clinical correlation between optic tract
edema and degree of visual abnormalities detected in this study.
Our patient did not have any visual complaints to start with but developed visual
complaints in a short period without any features of apoplexy. MRI showed bilateral
optic tract edema which could be the cause of her rapid deterioration of vision. Improvement
noticed in her vision after administration of steroids further substantiates our theory.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms.
In the form the patient(s) has/have given his/her/their consent for his/her/their
images and other clinical information to be reported in the journal. The patients
understand that their names and initials will not be published and due efforts will
be made to conceal their identity, but anonymity cannot be guaranteed.
