FP611: Clinical profile and Visual Outcome of Pitutary Adenoma Following TransSphenoidal Surgery.

Dr.Sucheta Parija, S09161, Dr. Lalitha C.S.

Abstract

The study reports the clinical profile and visual outcome of pituitary adenoma (PA) in patients treated by transsphenoidal surgery (TSS). A retrospective analysis of 38 cases of PA undergone resection from January 2015 – 2017 in tertiary hospital. Visual patterns before and after surgery were evaluated and correlated with age, duration of symptoms, pre- and post-operative visual acuity, visual field (VF). 23 females and 15 males had primary PA, their mean age was 42.7 year.  22 patients presented with visual symptoms ranged from decreased visual acuity and VF defect to complete blindness.  Improvement in vision after TSS was 75%. Visual acuity in 14 cases showed significant improvement. VF defect recovered in 65.5% of the affected eyes.  Best prognosis was seen with symptoms less than one year duration and age less than 50 years. TSS is a safe procedure for PA patients with visual impairment. Awareness among ophthalmologists regarding reversibility of visual loss needs to be increased.

Introduction

Pituitary adenomas account for about 10%-12% of intracranial neoplasms. They often remain undiagnosed, and small pituitary tumours have an estimated prevalence of 16.7%. The diagnosis is generally entertained either on the basis of visual impairment arising from the compression of the optic nerve by the tumour, or on the basis of manifestations of excess hormone secretion, the specifics depend on the type of hormone.

Visual field defects caused by pituitary adenomas are unique, with bitemporal hemianopia being most common. This is because of the distribution of visual fibres in the chiasm and their anatomic proximity to the sella turcica. Sometimes the visual fields are normal if the pituitary adenomas are small not causing significant optic compression.

The treatment of choice is surgical for pituitary macroadenoma. The mass resection is indicated early and importance of decompression of the optic pathway of these lesions lies in preventing the progression of structural damage to the visual pathway and allowing restitution of functional damage, the degree of postoperative recovery being difficult to determine and variable among patients.

With the advancement of technology, the preferred treatment is surgical removal by the transsphenoidal route because it is less invasive and allows direct approach to the pituitary gland.In this study, we focused on the clinical profile and visual outcome of patients of pituitarytumours treated by transsphenoidal surgery.

Material and Methods

A total of 38 patients who were diagnosed as pituitary adenoma and operated by transsphenoidal approach from January 2015-July2017 in the department of neurosurgery at a tertiary care hospital in eastern India were included. This was a retrospective study and the data was reviewed and analysed from the medical records. Patients with pure intrasellar lesions and adenomas operated through transcranial approach and with irregular followup were excluded from the study.Patients with preoperative ophthalmological assessment, and with at least six months of followup were included for further analysis.

All the patients were evaluated by the ophthalmologist along with the neurological examination. The visual acuity, visual field charting, colour vision and the fundus examination of each patient were evaluated. Endocrine workup and neuroimaging was done in all cases.

All the patients were evaluated by magnetic resonance imaging (MRI) brain plain with or without contrast.The adenomas were classified into microadenoma (< 10mm),macroadenoma (> 10-40mm) and giant adenoma (>40 mm). The adenoma volume was calculated by the De Chiro and Nelson formula [volume = (sagittal × coronal × axial diameters) × π/6]. Modified Hardy’s classification was used for staging (extension) and grading (degree of sellar destruction) of the pituitary adenomas. Based on clinical features, hormone profile, and immunohistochemistry (IHC) of the tumour tissue, pituitary tumours were classified as: (i) Nonfunctional, or (ii) functional: prolactinoma, somatotropinoma, corticotropinoma, and thyrotropinoma.

All the patients underwent transsphenoidal resection of pituitary adenomas. The extent of resection of the tumour (total or partial) was recorded as documented in the operative notes.All the patients were evaluated in the department of ophthalmology preoperatively and followed up after surgery in the 1, 3, 6 months and last follow-up visit postoperatively.

Data was entered in Excel software (Microsoft, Seattle, WA) and analysed was done using the SPSS software, version 13.0 (SPSS, Inc. Chicago, IL, USA). Quantitative data were described as mean and standard deviation with their 95% confidence interval. Categorical data were shown as frequencies and proportions. Comparison of categorical variables between the two was performed using the Chi-square test, and a P < 0.05 was considered significant.

Results

The mean age at presentation was 42.7 years (range 18-78 years). There was a female predominance in this study (1.4:1).The mean duration of symptoms from onset to diagnosis was 8.5 months(30 days to 2 years).

Headache and visual impairment were the most common symptoms and were present as the initial complain in 17 (44.7%) casesand 14 (36.8%) of patients, respectively.(Table 1) Endocrinological manifestations were present in 18 (47.4) % of patients.

Table 1: Pattern of clinical presentation

 

Presenting Complaints	Character	Frequency (%)
	Headache	84.2
	Visual deficit	81.6
Endocrine  symptoms	Hypothyroidism	7.9
	Hypocortisolism	15.8
	Galactorrhea	5.2
	Cushing	18.4
Others	Apoplexy	10.5
	Seizures	5.2
	Diplopia	5.2
	Focal neurodeficit	2.6
	Altered sensorium	2.6

Visual symptoms were present for <6months in  58.1%, for 6 months to 1year in 20.9% and 1 year to 2.0 years in 16.1% and > 2years in 4.8%. There was no perception of light in 3.4% of eyes. Bitemporal hemianopia was the commonest type of field defect 53.2%, followed by blindness in 3.4%. The frequency of upper and lower temporal quadratic defect did not show a significant difference.(Table 2) The visual field defect was detected during routine examination in 8.0 % cases for the first time.

Table 2 : Type and Frequency of Visual field defects

 

Visual Field	No of eyes	Frequency (%)
Normal	16	27.6
Bitemporal Hemianopia	31	53.4
Upper quadrant temporal field defect	4	6.8
Two quadrant TFD	3	5.1
All quadrant TFD	2	3.4
Blind	2	3.4

In the postoperative period, the overall visual acuity improved in 42 eyes (55.3 %). (Table 3) The significant visual acuity changes was observed in cases who had a good preoperative visual acuity (77.4%). Out of the six blind eyes, one showed visual improvement (16.7%).The overall deterioration was marked in three eyes (93.9%) in the immediate postoperative period due to postoperative hematoma in two cases which subsequently regained vision after clot removal and during follow-up. The other cause of visual loss after surgery may be attributable to optic nerve injury or surgical (ethicon) placement. Most of the visual improvement was marked after 6months to one year of surgery.

Table 3:Comparison of preoperative visual status and postoperative visual outcome

Visual Acuity	Preoperative Visual acuity (Total eyes)	Postoperative Visual outcome (%)   No Change	Improved	Worse
6/6-6/24	31	6 (19.4)	24 (77.4)	1(3.2)
6/36-6/60	18	6 (33.3)	11 (61.1)	1 (5.5)
<6/60-FC	9	5 (55.6)	3 (33.3)	1 (11.1)
HM	8	6 (75.0)	2 (25.0)	0  (0.0)
PL +ve	4	3 (75.0)	1 (25.0)	0  (0.0)
Pl –ve	6	5 (83.3)	1 (16.7)	0  (0.0)

Optic disc pallor was present in 24 (32.9%) % of cases. Optic atrophy was seen in 10 (13.2 %) of patients. There was significant positive correlation between the occurrence of optic atrophy and the duration of visual symptoms. Optic atrophy was present in 1.3% patients who had the duration of visual symptoms < 6 months, while optic atrophy was present in 11.8 %in those with duration of symptoms > 1 year (p<0.009).

Table 4: Correlation of various factors with visual outcome

Characters	Vision improved	Vision same or deteriorated	p-value
Mean age	42.75±1.662	56.2±2.781	0.009
Duration of visual symptoms <1year > 1year	34 (44.7%) 8.0 (10.5%)	12(15.8%) 22(28.9%)	0.001
Mean diameter	28.43±1.06	41.42±4.11	0.010
Mean Suprasellar extension	16.63±0.78	21.28±3.15	0.065

The patients with a duration of visual symptoms< 1 year had a better visual outcome with those with a longer duration (p<0.009).The patients who were less than 50 years had a better visual outcome. Visual outcome was inversely correlated with the size of the adenoma with statistical significance as shown in the Table 4.

Discussion

Pituitary adenoma are the most commonly encountered intracranial neoplasm, but its incidence has not been established with certainty. Review of literature for the prevalence of these tumours in an autopsy series reported to be 5-20% while clinically apparent pituitary adenomas represent 10-12% of all intracranial tumours.

The age factor as a predictor of the visual improvement after surgery has varied opinion. The study by Cohen et al observed that the visual outcome (visual acuity and visual fields) was better in patients < 52 years. Sullivan et al and Powell in their study concluded that the patient age was not predictive of postoperative visual acuity.In our study the patients who were below 50 years had a better visual prognosis than older age group. The reason behind this inconsistency regarding the effect of age on the visual outcome cannot be clearly explained. This may be related to the differences in the patient population studied, duration of the visual problems the patient is suffering, preoperative visual impairment and the mean size of the tumour.Another reason could be due to decreased capability of neuronal regeneration with advancing age.

Cohen et al reported that the visual outcome was better with shorter duration of symptoms.Symon et al in their study also observed that the degree of visual impairment correlated with the duration of visual complaints.Thotakura et al also reported that the patients with visual symptoms of less than one year duration had a better visual outcome after surgery which correlated with our findings. Dutta et al reported that early recovery of vision was noted in patients if the duration of symptoms was short. However, the ultimate outcome was good at the end of one year irrespective of the duration of the symptoms. Our study reported that the visual outcome was poorer with longer duration of visual symptoms.This result could be because the increase in the visual symptoms resulted in irreversible injury to the compressed visual pathways either by mechanical compression or by vascular compromise.

A good preoperative visual acuity also influenced for a favourable postoperative outcome as reported by Cohen et al. Sullivan et al in their retrospective study of 45 patients concluded that the preoperative visual acuity was not predictive of postoperative visual acuity. Similarly Powell in his series of 67 patients, reported that preoperative visual defect did not correlate to the postoperative visual acuity. Agarwal et al reported that in some cases even if the initial visual acuity is compromised still there can be regain of visual acuity after surgery if the duration of symptoms are less. This is explained by the term neuropraxia,a disorder in peripheral nervous system, in which the axonal conduction is blocked temporarily which again regains full recovery within 6-8 weeks.

The fundoscopic sign of long-standing chiasmal compression from a pituitary macroadenoma is primary optic atrophy secondary to retrograde axonal degeneration. Long-standing compression by a pituitary macroadenoma leads to optic atrophy. In a study by Dhasmana et al., optic atrophy was seen clearly in 17% of patients with pituitary adenomas, and all of them had significantly affected vision (VA, 20/100 or worse). In our study too, similar percentage of patients presented with optic atrophy, and most of the patients had a poor VA ranging from 6/36- 6/60 to no light perception.

Gnanalingham et al reported that the extent of the visual field recovery was mainly dependent on the preoperative visual field deficit. Dutta et al, reportedthat bitemporal hemianopia was the most common type of field defect (47.6%), and suprasellar extension of the tumour was present in 89.2% of the patients.The authors found that 82% of the patients with less severe visual deficits had improvement in visual status, whereas only 10% of the patients with no perception of light improved.Macro adenomas typically start compressing the crossing fibres of the chiasma first, creating the typical bitemporal hemianopia. Visual acuity changes are caused by compression of the macular fibres at a later stage of the disease.

The size of the tumour and extrasellar extension also influence the visual acuity outcome. Symon et al reported that the degree of visual improvement correlated with the size of the tumour. Thotakura et al also reported that better visual outcome will be achieved in patients with adenomas with mean diameter size < 36.5mm.

Recent advances in technology has made neurosurgical approach to pituitary tumours from microscopic approach to endoscopic assisted, and lastly to pure endonasal endoscopic approach. This has revolutionised the quality of visualisation and also the extent of approach, therefore increasing the limits of surgical access to the sella and suprasellar area.There are few limitations in this study, regarding the retrospective aspect, small sample size, and limited followup period.

Conclusion

 The final visual outcome appears to depend on the suprasellar extension of the tumour,but it was good in the long-term follow-up .There is a definite finding that the speed of recovery of vision was proportional to the duration of visual deficits. While improvement is to be expected gradually by 6 months, the deficit present for one year takes at leastone year to show improvement. Clinicians and the ophthalmologists should be aware of this fact and even be more patient when dealing with subjects with a longer onset-surgery interval. Ophthalmologist play a key role in guiding the neurosurgeons to operate on cases earlier for better visual outcome.

Reference

1. Cohen AR,cooper PR,Kupersmith MJ,Flamm ES,Ransohoff J.Visual recovery after transsphenoidal removal of pituitary adenomas. Neurosurgery.1985;17:446-52.
2. Mortini P, Losa M, Barzaghi R, Boari N, Giovanelli M. Results of transsphenoidal surgery in a large series of patients with pituitary adenoma. Neurosurgery 2005;56:1222-33.
3. Dutta P, Gyurmey T, Bansal R, Pathak A, Dhandapani S, Rai A, et al. Visual outcome in 2000 eyes following microscopic transphenoidal surgery for pituitary adenomas: Protracted blindness should not be a deterrent. Neurol India 2016;64:1247-53
4. Barzaghi LR, Medone M, Losa M, Bianchi S, Giovanelli M, Mortini P. Prognostic factors of visual field improvement after trans-sphenoidal approach for pituitary macroadenomas: Review of the literature and analysis by quantitative method. Neurosurg Rev 2012;35:369-78.
5. Dhasmana R, Nagpal RC, Sharma R, Bansal KK, Bahadur H. Visual fields at presentation and after trans-sphenoidal resection of pituitary adenomas. J Ophthalmic Vis Res 2011;6:187-91.
6. Gnanalingham KK, Bhattacharjee S, Pennington R, Ng J, Mendoza N. The time course of visual field recovery following transphenoidal surgery for pituitary adenomas: Predictive factors for a good outcome. J Neurol Neurosurg Psychiatry 2005;76:415-9.
7. Elgamal EA, Osman EA, El-Watidy SM, Jamjoom ZB, Hazem A, AL-Khawajah N, et al. Pituitary adenomas: Patterns of visual presentation and outcome after transsphenoidal surgery – An institutional experience. Internet J Ophthalmol Vis Sci 2006;4:2.
8. Kerrison JB, Lynn MJ, Baer CA, Newman SA, Biousse V, Newman NJ. Stages of improvement in visual fields after pituitary tumor resection. Am J Ophthalmol 2000;130:813-20.
9. Agrawal D, Mahapatra AK. Visual outcome of blind eyes in pituitary apoplexy transsphenoidal surgery: A series 14 eyes. Surg Neurol 2005;63:42-6.
10. Parent AD. Visual recovery after blindness from pituitary apoplexy. Can J Neurol Sci 1990;17:88-91.
11. Dhandapani M, Gupta S, Dhandapani S, Kaur P, Samra K, Sharma K, et al. Study of factors determining caregiver burden among primary caregivers of patients with intracranial tumors. Surg Neurol Int. 2015; 6:160.
12. Suri A, Narang KS, Sharma BS, Mahapatra AK. Visual outcome after surgery in patients with suprasellar tumors and preoperative blindness. J Neurosurg 2008;108:19-25.
13. Sullivan LJ,O’Day J,McNeill P. Visual outcomes of pituitary adenoma surgery.St.Vincet’s Hospital 1968-1987.J Clin neuroophthalmol.1991;11:262-7.
14. Powell M.recovery of vision following transsphenoidal surgery for pituitary adenomas. Br J neurosurg. 1995:9:367-73.
15. SymonL,Jakubowski J. transcranial management of pituitary tumours with suprasellar extension. J neurol neurosurg psychiatry.1979;42:123-33.
16. Thotakura A K,Patibandia M R, Panigrahi,Addagada G C.Predictors of visual outcome with transsphenoidal excision of pituitary adenomas having suprasellar extension: a prospective series of 100 cases and brief review of the literature. Asian J Neurosurg.2017;12(1):1-5.
17. Barzaghi LR, Medone M, Losa M, Bianchi S, Giovanelli M, Mortini P. Prognostic factors of visual field improvement after trans-sphenoidal approach for pituitary macroadenomas: Review of the literature and analysis by quantitative method. Neurosurg Rev 2012;35:369-79.