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|EXPERT COMMENTARY ON PEARLS FROM PAST - “SURGICAL EXPERIENCE OF EIGHTY CASES OF ACOUSTIC NEURINOMA”
|Year : 2020 | Volume
| Issue : 2 | Page : 262-263
Vestibular Schwannoma: Half a Decade Odyssey from Challenges to Functional Preservation
Adesh Shrivastava1, Anirudh Nair2, Suresh Nair1
1 Department of Neurosurgery, AIIMS, Bhopal, Madhya Pradesh, India
2 Department of ENT, AIIMS, Raipur, Chhattisgarh, India
|Date of Web Publication||15-May-2020|
“Shree”, SRA No. 21, TC 16/3242, Sreemoolam Road, Kumarapuram, Trivandrum - 695 011, Kerala
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Shrivastava A, Nair A, Nair S. Vestibular Schwannoma: Half a Decade Odyssey from Challenges to Functional Preservation. Neurol India 2020;68:262-3
It was Annandale in 1895 who successfully removed an acoustic neuroma using the enucleating finger technique. The mortality rate for finger enucleation technique at the beginning of the last century was 72 to 84%, and the poor result was attributed to avulsion of an anterior inferior cerebellar artery causing horrendous bleeding and brainstem infarction. Cushing compared this complication with the infamous fence corner at the battle of Gettysburg, suggesting that the cerebellopontine (CP) angle should be called the “the bloody angle.” Over the ensuing few decades, because of the high mortality, surgeons attempted the procedure only when the tumor became large and symptomatic. When India became independent in 1947, neither were there any neurosurgery departments in India nor were there any trained neurosurgeons. Whatever small neurosurgery was taking place in the country was being performed by general surgeons. It was in the year 1949, when Prof Jacob Chandy returned to Christian Medical College, Vellore after his neurosurgical training in Canada and the United States, which marked the dawn of neurosurgery in India.
During this time, surgery for vestibular schwannomas (VSs, then popularly called acoustic neuroma), had advanced from the concept of finger nucleation to internal decompression followed by capsule dissection. There had been excellent papers in the literature by the likes of Horrax and Olivecrona,, describing the technique with the use of electrocautery and gel foams even during the 1930s and 1940s. By the mid-1950s it was evident from the reports that the key to bringing down the morbidity and mortality in these cases was total tumor excision with injury avoidance to the brainstem. However, the Indian scenario was different. With major constraints of infrastructure and skilled manpower, a small team of neurosurgeons in south Indian township of Vellore began operating on cases of VSs. The diagnosis depended upon a thorough clinical evaluation with limited investigations in the form of X-rays, ventriculograms, and direct puncture angiograms. There was hardly any scope of preoperative study of the expected pathoanatomy as we have today.
It was in the year 1966 that the Vellore group compiled their experience of 80 cases of VSs and came up with their findings in the 14th volume of Neurology India. The morbidity and mortality results were comparable to the past series of Olivecrona and Horrax. The publication of this series by the Vellore group did bring a great deal of confidence in the Indian neurosurgical community that paved the way for further development of neurosurgery super-specialty in India. Those were the days when the majority of patients were diagnosed very late. In this series also the predominant presentation symptoms were visual deterioration (80%), unsteadiness, headache (60%), vomiting (40%), and deafness (20%). It is interesting to note that deafness was the presenting symptom in only one-fifth of the cases, even though more than 90% of cases showed audiometric dysfunctions on laboratory testing. This reiterated that to diagnose a CP angle pathology, a clinician had to work with a high index of suspicion and carefully analyze the history and examination findings. This still holds good today and all the residency training programs in India still give major emphasis to clinical localization and differential diagnosis. The only radiological investigations available at that time were X-rays, cisternograms, ventriculograms, and direct puncture angiograms. The enlargement of the internal auditory meatus which was the hallmark for the diagnosis of VS on X-rays still holds value when radiologically challenging lesions are encountered. In fact, in this series, the authors mention that the Towne's and Stenver's views of the skull were of diagnostic value in 85% of the cases. Further, with the addition of pneumoencephalogram and rarely vertebral angiograms in a few, preoperative diagnosis of acoustic neuroma was made in 90% of cases. Such a degree of accuracy in the differential diagnosis after successful clinical localization in those days in India was a major feat in itself. For the surgeons of today to imagine diagnosing a CP angle schwannoma without a CT or an MRI is unimaginable. With very limited surgical facilities in terms of infrastructure, this series by the Vellore group was one of the largest of those times. There were no microscopic illumination or magnification, basic electrocautery, and hardly any refined instruments in those days. All these challenges would have been discouraging but to the zeal of the group to move ahead that these cases could be operated upon. While this team could achieve a primary total excision in 54 of the 80 cases, it was subtotal in the remaining 26, with mortality rates of 16.5% and 27.5%, respectively. This was comparable to many western series of those times. It was only 4 years later that Prof B Ramamurthi and his colleagues from then erstwhile Madras published their series of 122 cases of VS of which 84 were operated upon., His results were also comparable to those of Sambasivan et al. and the west which, again proved that the Vellore group had ignited the spark of quality contemporary neurosurgery in India. Our understanding of the microsurgical anatomy of the cisternal spaces and the contents in and around the CP angle area and about the site of origin of this tumor and its relationship with the arachnoid anatomy., have significantly improved surgical extirpation of even larger tumors with functional preservation of not only facial nerve but also hearing in selected cases., We have a better understanding presently of cystic VSs which can present with a short history, overt facial weakness and intratumoral bleed. Total resection may not be possible in some cases, especially the cystic ones, and surgeons should realize that discretion is the better part of valour in these cases. We have the current option of gamma knife surgery not only for smaller tumors but also for treating deliberate residual tumour, which is left behind for functional preservation.
| » Conclusion|| |
Acoustic neurinomas have gone from being a death sentence at the turn of the last century to being safely treated with multiple therapeutic options that concentrate on the facial nerve and hearing preservation. We believe that this seminal paper from the early dawn of Indian neurosurgery brought India to the international neurosurgical forefront. It was probably the encouragement from the results of this series that Indian neurosurgeons started publishing their surgical experience, presenting not just their results but also describing the surgical approaches and technical nuances of VS surgery. Around 54 years down the lane, since the publication of this paper, the present-day neurosurgeon, who is unlikely to see a VS patient presenting with blindness or altered sensorium, with all diagnostic and operative armamentarium at hand, will have to decide on managing incidental VSs with normal hearing.
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