Ophthalmology

Introduction

Craniopharyngioma is the most frequent non-glial suprasellar tumor in children.¹ Despite neurosurgical and treatment modality developments, this disease is still associated with a poor prognosis and severe morbidities due to its close anatomic relation to surrounding structures and its common recurrence.^2–4

Few reports have addressed the factors associated with visual outcome in cases of craniopharyngioma, although a younger age and visual symptoms at presentation are known to be related to a poorer visual outcome.⁵ There has been no study that obviously addressed the relationship between the visual outcome and the size of the tumor. Postoperative visual acuity was also found to depend on the severity of reduced preoperative visual acuity.^6–8 However, the significance of the preoperative visual field as a clinical indicator has not been subjected to analysis. Thus, this study was undertaken to investigate whether the preoperative visual field is related to presenting symptoms and whether it can be used as a prognostic factor of postoperative visual outcome and recurrence in children with craniopharyngioma.

Patients and Methods

Thirty-two children (20 boys and 12 girls) 15 years of age or younger with craniopharyngioma were identified, and 27 children (15 boys and 12 girls) with an available preoperative visual field data were included in this study. Institutional review board approval was obtained. Kinetic perimetry was performed by two experienced visual field testers. Visual field examinations were performed using a Goldmann perimeter (Haag-Streit, Bern, Switzerland). Two stimuli of the same size (0.25 mm²) but of different intensity (I-2e = 100 apostilb and I-4e = 1,000 apostilb) were used to draw isopters to detect visual field defect. Visual field results were classified as bitemporal hemianopia, unilateral hemifield defect, homonymous defect, unilateral loss of central visual function (a central visual loss in one eye and a normal visual field in the other), anterior junction syndrome (a central visual loss in one eye and a temporal visual field defect in the other), inferonasal island, and normal, referring to the previous report.⁶

Patients were divided into two groups according to preoperative visual field: the normal group and the abnormal group that included the above visual field defects. Age at diagnosis, presenting symptoms, duration of chief complaint, and preoperative and postoperative best-corrected visual acuities were compared between the normal and the abnormal groups. Preoperative magnetic resonance imaging scans were investigated, and the greatest diameter of the tumor was measured and compared between the two groups.

All patients underwent a gross total removal of craniopharyngioma using a transcranial or a transsphenoidal approach. A complete excision was confirmed by a negative postoperative neuroradiologic examination. Diagnosis was confirmed histopathologically. Recurrence, postoperative visual acuity, and visual field were evaluated and compared between the two groups.

Continuous variables were analyzed using the Mann–Whitney U test, and crosstabs data were analyzed using Fisher’s exact test. Clinical significance was accepted for P values less than .05. All statistical analyses were performed using SPSS for Windows, Version 11.0.0 (SPSS Inc., Chicago, IL).

Results

Thirteen of 27 patients (48.2%) presented with systemic symptoms as a chief complaint and 14 (51.9%) with ocular symptoms. Mean symptom duration was 7.38 ± 9.02 months. Systemic symptoms included headache (18 patients, 66.7%), nausea and vomiting (6 patients, 22.2%), polyuria and polydipsia (8 patients, 29.6%), and growth retardation (5 patients, 18.5%). Ocular symptoms included visual disturbance (12 patients, 44.4%), diplopia or strabismus (4 patients, 14.8%), a constricted visual field (1 patient, 3.7%), and orbital pain (1 patient, 3.7%).

Of the 27 patients, 12 (44.4%) had visual acuities of 20/40 or better in both eyes. Nine (33.3%) patients had a visual acuity of 20/40 or better in one eye and worse than 20/40 in the other, and 1 (3.7%) had visual acuities between 20/200 and 20/40 in both eyes. Three (11.1%) patients had a visual acuity between 20/200 and 20/40 in one eye and of 20/200 or worse in the other eye. Two (7.4%) patients had visual acuities of 20/200 or worse in both eyes (Fig. 1).

Figure 1. Visual acuities at initial presentation and at postoperative follow-up.

Of the 27 patients, 13 (48.1%) had a normal visual field preoperatively, 3 (11.1%) showed bitemporal hemianopia, and another 3 (11.1%) showed unilateral temporal defect. Unilateral loss of central visual function was observed in 2 patients and anterior junction syndrome in 3 patients. Two patients had homonymous defects and 1 patient showed loss of central visual function of one eye and an inferonasal island in the other eye (Fig. 2).

Figure 2. Types of visual field defects preoperatively and postoperatively.

Age at diagnosis was 8.2 ± 3.3 years in the normal group and 8.2 ± 3.2 years in the abnormal group (P = .98). In the normal group, 7 patients presented systemic symptoms and 6 patients presented visual symptoms as a chief complaint. In the abnormal group, 7 patients complained of systemic symptoms and the remaining 7 patients presented with visual symptoms. The ratio of patients with systemic symptoms to visual symptoms was not significant between the normal and the abnormal groups (P = 1.0). Chief complaint duration was 5.2 ± 6.8 months in the normal group and 8.9 ± 10.6 months in the abnormal group (P = .32).

Ten of the 13 patients (76.9%) in the normal group and 8 of the 14 patients (57.1%) in the abnormal group complained of a headache (P = .42). Decreased visual acuity was present in 4 of the 13 patients (30.8%) in the normal group and 8 of the 14 patients (57.1%) in the abnormal group (P = .25). No patient in the normal group and 7 of 14 patients (50.0%) in the abnormal group had polyuria or polydipsia (P = .01). One of the 13 patients (7.7%) in the normal group and 5 of the 14 patients (35.7%) in the abnormal group had growth retardation (P = .16).

Preoperative optic disc findings were retrieved for 23 patients (10 patients in the normal group and 13 patients in the abnormal group). In the normal group, 12 eyes were normal, 4 eyes showed disc edema, and the other 4 eyes had pallor. In the abnormal group, 10 eyes showed normal appearances, 6 eyes presented with disc edema, and 10 eyes had pallor. Comparison of optic nerve head appearance showed no significant difference between the two groups (P = .66, Fisher’s exact test).

Preoperative brain magnetic resonance imaging scans were available for 22 patients (11 in the normal group and 11 in the abnormal group). All tumors were suprasellar masses with both solid and cystic components. Calcification was observed in 18 patients. Three patients showed hydrocephalus. Greatest diameter of the tumor was 28.4 ± 11.2 mm (range = 15 to 53) in the normal group, and 35.45 ± 11.52 mm (range = 20 to 60) in the abnormal group. There was no statistically significant difference of tumor size between the two groups (P = .15, Mann–Whitney U test).

All 27 patients underwent gross total removal of craniopharyngioma. The mean follow-up period was 48.9 ± 35.4 months in the normal group and 60.5 ± 58.8 months in the abnormal group (P = .35). Eleven patients (40.7%) experienced recurrence. Mean time between surgery and recurrence was 44.09 ± 46.46 months (range: 6 to 170 months). One of the 13 patients (7.7%) in the normal group and 10 of the 14 patients (71.4%) in the abnormal group experienced recurrence (P < .001).

At the most recent follow-up, 11 (76.9%) patients in the normal group and 1 (0.07%) patient in the abnormal group had postoperative visual acuities of 20/40 or better in both eyes (P < .001). Thirteen (48.1%) patients had a visual acuity of 20/40 or better in one eye and a visual acuity of worse than 20/40 in the other, and 2 (7.4%) patients had visual acuities of worse than 20/200 in both eyes (Fig. 1).

Postoperatively, 8 patients (29.6%) in the normal group had a normal visual field. Of the other 19 patients, 6 (22.2%) had bitemporal hemianopia and 3 (11.1%) had unilateral temporal defect. Unilateral loss of central visual function was observed in 6 (22.2%) patients and anterior junction syndrome in 3 (11.1%) patients. One patient (3.7%) had a loss of central visual function of one eye and an inferonasal island in the other (Fig. 2).

Discussion

Our study shows that patients with a normal visual field at presentation are more likely to preserve better visual acuity in both eyes and a normal visual field postoperatively. No study has previously suggested that visual field at presentation is an important prognostic factor in craniopharyngioma.

Some have reported on the clinical implications of initial visual field in other tumors. Findlay et al. reported a significant correlation between visual field at presentation and visual field after treatment for pituitary tumors.⁹ However, the relationship with postoperative visual acuity was not assessed. Rivoal et al. showed that 96% of patients with acromegaly with a normal visual field achieved a preserved normal visual field at the end of the study, which contrasted with the 45% of patients with an abnormal visual field who achieved a normal visual field.¹⁰ The relationship between the tumor size and the visual outcome has not been verified in craniopharyngioma. In the current study, there was no statistically significant difference of the tumor size between the normal group and the abnormal group.

Several reports have investigated visual impairment at presentation and the visual outcome of craniopharyngioma in children. Repka et al. evaluated preoperative and postoperative visual acuities and visual fields in children younger than 18 years old and found that 17% of patients had visual acuity of worse than 20/40 in the better eye at the time of diagnosis and 27% of patients continued to have visual acuity of worse than 20/40 in the better eye postoperatively.¹ As to visual field, 43% of children had a normal visual field at presentation and 46% postoperatively. However, individual visual acuity and field changes were not analyzed in this study and no factors were suggested to be associated with prognosis. Abrams and Repka addressed the notion that a younger age and the presence of a visual symptom at presentation indicated an increased risk of permanent visual impairment; however, visual field was not included.⁵ Chen et al. assessed clinical presentation and visual outcome in adults and children with craniopharyngioma.⁶ They commented that changes in visual acuity at initial and final visits were not significant, and that in terms of visual field, bitemporal hemianopia was the most common defect, especially in children; pleomorphism occurred in some patients. However, they too did not analyze the prognostic implications of visual field at presentation.

In the current study, visual field at presentation was related to specific presenting symptoms. A headache was the most common systemic presentation and visual disturbance was the most frequent visual complaint, which concurs with previous reports.^11–15 Polyuria, polydipsia, and growth retardation were associated with an abnormal preoperative visual field in the current study. All patients who complained of polyuria or polydipsia showed visual field abnormalities. It can be explained by a close locational relationship between optic chiasm and hypothalamus–pituitary axis.

One surprising finding of the current study concerns the association between an abnormal visual field at presentation and a higher recurrence rate. The main factor influencing recurrence is the extent of surgical resection because total removal carries a lesser risk of recurrence compared to subtotal or partial resections.^7,16–18 Also, a younger age, calcification, or hydrocephalus at presentation was known to be associated with a tendency to recur.^17,18 There were some debates on the tumor size as a risk factor for recurrence.^4,13,19

In the current study, all patients received grossly complete removal of the tumor and the average age was 8.00 ± 3.16 years for patients with a recurrence and 8.37 ± 3.16 years for those with no recurrence (P = .71, Mann–Whitney U test). The patients with abnormal visual fields had a longer follow-up period even though the difference was not statistically significant (P = .32). Further longer follow-up period and prospective study will be needed.

One of the possible causes of recurrence of craniopharyngioma is microscopic residual tumor capsule left behind at surgery. The inferior aspect of optic nerves and chiasm, the hypothalamus, and the third ventricle were known to be areas not easily accessible despite meticulous inspection with a micro-mirror or modern neuroimaging.²⁰ Kim et al. also reported that the optic nerve or optic chiasm was the most common adhesion site at the first surgical procedure and the most frequent recurrence site in pediatric craniopharyngioma.²¹ These findings might explain our results because preoperative abnormal visual field implies adhesion or compression of craniopharyngioma to optic nerve or chiasm.

A question can be raised about the reliability of visual field examination in young children. There were some articles about visual field testing in children.^22–24 Quinn et al. reported that visual field tests using Goldmann perimetry and a double-arc perimeter were reliable and comparable in children aged 4 to 11 years.²² Safran et al. showed that children aged 5 to 8 years did remarkably well regarding both the duration of the examination and the reliability of the answers.²³ Nesher et al. reported the feasibility of performing visual field testing with the frequency doubling technology in children aged 5 to 10 years.²⁴ In the current study, the youngest child at 3 years old showed normal visual fields of both eyes repeatedly—preoperatively and at 1 and 2 years after surgery. Furthermore, results of visual field examination were not ambiguous, so we could easily analyze and classify them in all patients.

Our study shows that preoperative visual field is a significant clinical indicator in children with craniopharyngioma. Preoperative visual field is a prognostic indicator of postoperative visual acuity, postoperative visual field, and recurrence, regardless of the tumor size. So in the case of the patient with preoperative abnormal visual field, more meticulous control of tumor during surgery is recommended and circumspect follow-up might be needed for recurrence even though the tumor was completely removed. In addition, it was found that polyuria and polydipsia was significantly associated with an abnormal visual field at presentation.