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NI FEATURE: JOURNEY THROUGH THE EONS - COMMENTARY
Year : 2018  |  Volume : 66  |  Issue : 1  |  Page : 9-19

Evolution of concepts in the management of vestibular schwannomas: Lessons learnt from Prof B Ramamurthi's article published in 1970


Department of Neurosurgery, Postgraduate Institute of Medical Education and Research, Chandigarh, India

Date of Web Publication11-Jan-2018

Correspondence Address:
Dr. Sunil Kumar Gupta
Department of Neurosurgery, Postgraduate Institute of Medical Education and Research, Chandigarh
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0028-3886.222846

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How to cite this article:
Gupta SK, Tripathi M. Evolution of concepts in the management of vestibular schwannomas: Lessons learnt from Prof B Ramamurthi's article published in 1970. Neurol India 2018;66:9-19

How to cite this URL:
Gupta SK, Tripathi M. Evolution of concepts in the management of vestibular schwannomas: Lessons learnt from Prof B Ramamurthi's article published in 1970. Neurol India [serial online] 2018 [cited 2019 Apr 19];66:9-19. Available from: http://www.neurologyindia.com/text.asp?2018/66/1/9/222846




“We know only too well that what we are doing is nothing more than a drop in the ocean. But, if the drop were not there, the ocean would be missing something.”

-Mother Teresa

First described in 1777 by Sandifort et al.,[1] surgical management of vestibular schwannoma (VSs) has been a challenging task for multiple generations of neurosurgeons. After the initial reports on the autopsy findings of these patients by Charles Bell, Cruveilhier, Oppenheim, and Sternberg (1900), the surgical reports by Cushing, Dandy, and Olivecrona paved the way for the surgical management of VN.[1],[2],[3],[4],[5],[6],[7],[8],[9],[10] Moscowitz et al., classified the history of VS surgery into five major eras: a. the pioneer era (1890-1925); b. the curative era (1925-1960); c. the magnification era with emphasis on facial nerve preservation (1960-74); d. the magnification era with emphasis on hearing preservation (1975-1990); and finally, the radiosurgical era, paralleling eras 'c' and 'd' (1960s until the present time).[2] Stereotactic radiosurgery (SRS) was first described by Leksell in 1951, and in 1969, Leksell and Bjorn Meyerson performed the first SRS for a VS.[11] The term 'Acoustic Neurinoma' is still in use; however, since these tumors take origin from the superior vestibular and not the acoustic division of the eighth cranial nerve, the correct terminology, vestibular schwannoma, is being used in this manuscript.[11]

Professors B. Ramamurthi (fondly called BRM), V. Balasubramaniam and S. Kalyanaraman published an article on “Acoustic Neurinomas” (being referred to as vestibular schwannoma [VS] throughout the present article) in the September 1970 edition of Neurology India.[12] In this article, he reported his experience and surgical technique in the management of 122 cases harbouring a VS. He highlighted that excision of VSs form a formidable challenge in India, requiring their early recognition and timely management with a good post-operative care. He observed that patients with these tumors were being diagnosed quite late in the absence of an early otological diagnosis. At that time, this was one of the largest series of VSs published anywhere across the world.[12] Several remarkable events occurred in this decade, which would probably result in the advent of the aptly termed 'modern neurosurgery' in relation to VSs. Herbert Olivecrona published his results related to the removal of 450 VSs between 1931-60.[10] He also discussed the long-term results following total and partial removal of VSs.[8],[9],[10] That decade marked a revival of interest among the neurosurgeons involved in attempting to achieve better results in patients with VSs. This was in contrast to the poor results and pessimism surrounding the heroic attempts by Cushing and Dandy in excising these tumors.[5],[6],[7] Another important personality, who significantly contributed to the transition to modern neurosurgery by his the introduction of the surgical microscope in 1961, was William House. He advocated the middle cranial fossa approach for removal of a VS, and later the translabyrinthine approach, but he soon realized that the middle cranial fossa approach was not suitable for larger tumors with significant posterior cranial fossa component.[13],[14],[15] Over the last two decades, development of SRS has brought about a paradigm shift in the management of small-to- medium sized VS.[15]

The article by Professors BRM, V. Balasubramaniam and S. Kalyanaraman still stands valid in the current era of increasing dependency on radiological investigations and in the times of the 'fading art of clinical diagnosis'. This article was a seminal contribution in its time with far-reaching implications that are relevant even today due to several reasons.


  Candid Confessions and Management Pitfalls Top


First, the number of patients included in the study by BRM et al., represented a very significant number for that time, as the contemporary international studies published during that era reported their experience with much lesser patients.[15],[16],[17] With his experience based upon surgical management in 122 patients harboring a VS, he discussed all the relevant points, including importance of an early otological diagnosis, the position of the patient, the controversies related to partial and total excision, the preservation of facial nerve, and the outcome.[12] During the same time, BRM also published an article on the neuro-otological features of VSs in the Indian Journal of Otolaryngology, in which he discussed the overriding importance of an early otological diagnosis.[18] He was very meticulous in keeping the records of his patients.[19] In 1995, BRM re-evaluated his experience with 510 cases of VS. In his introductory remark, he candidly confessed, “Forty-three years of experience, one would have thought, would take away the anxiety and nervousness associated with a common clinical situation, but acoustic neurinomas have proved an exception to this rule.”[20] It is remarkable to note, that in the significant time duration ranging from 1949 to 1993, much water had passed under the bridge, and the neurosurgical operation theatres had witnessed significant improvements right from introduction of innovative diagnostic tools to a meticulous intraoperative monitoring of cranial nerves, and better surgical equipment, and yet the challenges encountered and highlighted in the two paper written by him still remained the same. Even with the advent of advanced imaging modalities, small-sized VSs (<1.5 cm diameter) were a rarity (only 3 out of 196 patients had a small-sized VS in the computed tomographic [CT] scan era, 1980-93). The mortality figures, however, had improved in the three eras classified earlier on in this article, with the focus subtly shifting over the years from life preservation to functional preservation.[20]


  Emphasizing the Role of an Otorhinolaryngology Colleague Top


Second, this seminal paper strongly advocated the early detection of otological findings in patients harbouring a VS, and defined the immense role the otorhinolaryngology colleagues may play in the early identification and evaluation of this disease. BRM repeatedly found that none of these patients were diagnosed or referred by the otorhinolaryngology specialists and the diagnosis was suspected only after the onset of neurological symptoms. The majority of his patients presented late in the natural course of the disease, often with large-volume tumors, with the patients suffering from nearly complete hearing impairment, gross cerebellar signs, and sometimes even with complete visual impairment.[12],[18],[19],[20] He also described the recognition of early-onset of deafness in VSs to differentiate them from other tumors of the cerebellopontine angle (CPA).[18] He emphasized the need for taking the help of an otorhinolaryngologist in performing the battery of otological tests for evaluating cochlear and vestibular functions. He advocated that neuro-otology should be an integral part of the Neurosurgery and Otorhinolaryngology residency programs. Such well-laid out points have led to a paradigm shift in the management of VSs as a majority of the patients are now being referred for surgery with a small-sized tumor, having been detected much earlier in the course of their disease, based upon the emphasis that Dr. BRM and his colleagues had placed on the early detection and management of these tumors.[20],[21],[22],[23]


  Radiological Diagnosis Top


Third, he strongly emphasized that neurosurgeons should be well versed in unequivocally establishing the diagnosis of VS. This recommendation was based upon imaging studies in an era when advanced radiological modalities such as a computed tomographic (CT) scan were not available in India, and neurosurgeons relied on plain radiographs and myodil ventriculograms for ascertaining the differential diagnosis of tumors of the cerebellopontine angle.[12] He described the proper utilization of non-invasive investigations like special views of plain radiographs of the skull, including the modified half axial (Towne's) view and the postero-inferior view through the orbit (transorbital view) showing the petrous part of the temporal bone, to identify the internal auditory meatus and auditory canal as well as their expansion/erosion in the presence of a VS. Greater than 57% of his patients had features of raised intracranial pressure (ICP) on plain radiographs and a few also presented with enlarged venous channels. For the latter, he described the need of an early plugging of the venous bleeding to prevent the chances of air embolism. Ventriculogram was only needed to evaluate the extent of the lesion.[12],[18],[19],[20] These points are now of historical importance due to the ready availability of sophisticated radiological tools; nevertheless, the emphasis of the paper by BRM et al., on establishing an early diagnosis of VSs by non-invasive investigations still holds valid.


  Surgery for Vestibular Schwannomas Top


Fourth, BRM et al., discussed the operative approach to a VS in great details in this article. The management of preoperative raised intracranial pressure, the patient positioning, the role of cerebellar lobectomy, the variations in surgery required based upon the consistency of the tumor as well as the direction of tumor spread, the emphasis on facial nerve preservation, and the pointers to decision-making between a partial and total surgical excision were all dealt with in the article. All these technical pearls remain relevant even in the modern neurosurgical era. The direction of tumor spread is a very important criterion for choosing the operative approach and for ensuring the functional preservation of cranial nerves in the vicinity of the tumor. In the presence of a narrow and steep space within the cerebellopontine angle, the direction of spread is chiefly upwards and the trigeminal nerve gets involved early; in the presence of a wider and shallower space at the region, the spread is inferior, with the lower cranial nerves being involved early.[12],[18],[19],[20]

The relevance of this paper in the current scenario: The management of vestibular schwannomas

Clinical features and diagnosis

In this article, BRM et al., mentioned that an early sign of facial nerve involvement is a slight lid lag during eye blinking, and that the sensory loss over the corneal surface (due to the additional functional impairment of the trigeminal nerve) was more frequent than the more obvious motor involvement of the facial nerve. Lower cranial nerves were reportedly involved in 50%, and cerebellar lobe in 70% of his patients, and papilledema was present in 90% of the patients.[12],[18] In the earlier publication brought out in 1970,[12] 40% of the patients suffered from complete visual impairment at presentation;[12],[18],[19] while in the later series published in 1995, only 16% suffered from complete visual impairment.[20] Currently, majority of the patients are being referred by the ear nose throat (ENT) clinics after an incidental diagnosis of a quiescent lesion is made or after the tumor has been picked up upon a detailed evaluation of the causation factors responsible for the attacks of vertigo and tinnitus occurring in a patient. The patients with neurofibromatosis with bilateral VSs are also being diagnosed early in their natural history and managed with other surgical techniques such as radiosurgery. Neurorehabilitation remains an integral component of the holistic care of a patient of VS, especially in the ones having syndromic manifestations and bilateral clinical manifestations, such as neurofibromatosis II, and was also touched upon in the seminal paper by BRM et al.[12],[18],[19],[20] An important aspect of the two papers, a culmination of the experience spanning 43 years in the management of VN, was that the treatment of the entire spectrum of tumor sizes from small ones to large-to-giant sized VNs was covered. This clear demarcation between different sized VNs and the differential treatment required for them has withstood the test of time.[12],[20] In his follow up article on the same topic published in 1995, he observed that a majority of VSs still presented in the late stages, having attained a large size, even in the so called CT era (1980-93). More than 2/3rd of the patients continue to present with tumors, which may be labelled as giant VSs (>4 cm in diameter)[20] despite the ready availability of modern imaging techniques (like the magnetic resonance imaging [MRI]). This stratification of tumor size paved the way for the utilization of advanced imaging modalities such as diffusion tensor imaging and tractography to define the relationship between various tracts as the well as the pathway of the cranial nerves in close proximity to a large-sized tumor.[21],[22] It also facilitated a radically different plan of management for patients with small-sized and intracanalicular tumors (Koos grade 1), in whom a close observation, utilization of the middle fossa approach, or stereotactic radiosurgery, with significant emphasis on functional preservation of the facial and vestibulocochlear nerves, take precedence.[23],[24],[25]

Management of associated hydrocephalus

In a majority of his patients, BRM et al., carried out ventricular drainage for 48-72 hours prior to surgery to facilitate the anaesthetic and surgical procedures, even though there was a significant risk of infection present.[12] Thus, BRM et al., highlighted two significant points that have an immense relevance even today: one was the emphasis on the management of hydrocephalus and raised intracranial pressure prior to the definitive excision of the tumor; and, the second was the stress on avoiding the placement of a permanent cerebrospinal fluid (CSF) diversion procedure like a ventriculoperitoneal shunt, prior to performing definitive surgical excision of the VS. The first point is of utmost importance during the initial part of surgery for a VS where a cerebrospinal fluid drainage procedure either by tapping the lateral ventricle, or by releasing CSF at the cisterna magna or the cerebellomedullary cistern, is mandatory to avoid the occurrence of cerebellar contusion due to retraction of the bulging cerebellar lobe; it also preserves the arachnoidal planes by permitting neuraxial structures to retract away from the tumor capsule. The second point helps to avoid the additional morbidity of a permanent CSF diversion procedure that may result in infection, repeated shunt obstructions, and abdominal complications such as the development of a pseudocyst. The definitive excision of the tumor facilitated by an initial ventricular or cisternal CSF drainage helps to relieve the obstructed CSF pathway. At present, therefore, the majority of neurosurgeons prefer to directly operate upon the tumor, relieving the mass effect over the cerebral aqueduct, in order to establish the CSF pathway. In the postoperative period, 10-15% of these patients may require a permanent CSF diversion procedure, either in the form of a ventriculo-peritoneal or a lumboperitoenal shunt, or a third ventriculostomy, due to the presence of persistent hydrocephalus or the development of a recalcitrant pseudomeningocele.[26]

Positioning

The multitude of patient positions advocated for resection of a VS points towards the fact that the controversy on the ideal patient position in which the patient harboring a VS should be placed in, still remains unresolved. The basic issue is that it is important for the surgeon to have a relaxed and a comfortable posture, when seated. This is needed for conduction of a smooth surgery over a prolonged duration. BRM and his colleagues operated upon most of their patients utilizing the sitting position. Only 2 patients were reported to be operated in the face-down position to avoid the complication of air embolism.[12],[18],[19],[20] Cushing advocated the bilateral suboccipital approach and subtotal excision in his series of cerebellopontine angle tumors.[4],[5] Olivecrona, in his paper published in 1967, described the face-down with head rotated position.[10] Charles Drake in his surgical technique promoted the sitting position to encourage the natural drainage of blood and CSF to keep the operative field clear.[17] In today's era, Professor Madjid Samii has probably the largest operated series of VSs. He is also a strong proponent of the sitting position. One clear disadvantage of sitting position is that it leads to hand fatigue during prolonged surgeries. Measures also have to be taken for the early detection and timely management of air embolism.

Most of the contemporary neurosurgeons prefer a three-quarter prone position to make the petrous bone perpendicular to the floor so as to have a direct visual access along the axis of the petrous bone. A few surgeons have shifted to the supine position with a shoulder-roll under the ipsilateral side with a slight head tilt, along with rotation of the table towards the opposite side. In this position, the cerebellum falls away from the operative field and a lesser degree of ipsilateral cerebellar lobe retraction is required. This possibly makes the positioning much simpler. It also makes the job of the anesthetist much easier, who neither has to deal with the much higher frequency of air embolism associated with the sitting position nor the compromised respiratory status in prone or three-quarter prone position.[23]

The concluding remark of the 1995 article by BRM et al., states, that “when one is used for many years to a particular approach to the cerebellopontine angle…, it is easier and safer to continue in the same approach instead of trying to change one's perspective and operating reflexes.”[20] This extremely sane advice is extremely useful for the neurosurgeons of the present era confronted with a plethora of surgical positions to approach a VS. It clearly states that the patient's position must be chosen based entirely upon the surgeon's level of comfort as well as his/her experience with that position.

Surgical technique

In the reported series by BRM et al., techniques to prevent tonsillar herniation from causing brain stem compression by removal of posterior arch of  Atlas More Details during the suboccipital craniectomy; and, removal of lateral one-third of the ipsilateral cerebellar hemisphere to combat a cerebellar bulge have been described. The latter maneuver primarily prevents undue traction on the cerebellar hemisphere that may occasionally lead to cerebellar contusion and postoperative morbid ataxia.[12] However, in present era, with the routine use of microscope and availability of better drills, the dimensions of craniotomy are much less. Removal of posterior arch of atlas is rarely required. Resection of lateral one-third of ipsilateral cerebellar hemisphere is not routinely practiced but remains a rescue measure. The surgeons in the index study did not make any deliberate attempts to save the facial nerve, as in the large and giant -sized tumors that they frequently encountered, preservation of life was of paramount importance.[12] However, their continuous emphasis on the need for functional preservation of the facial nerve has led to the concept of functional facial nerve preservation being firmly established in the echelons of surgery for VNs. With the detection of the tumor in its early stages and the availability of better intraoperative neuromonitoring tools in the present era, this thought that was conceptualized 40 years ago has become a reality.[27]

The article by BRM et al., also discussed the impact of consistency of the tumor in influencing the ease of surgical removal of the tumor. Traditionally, soft tumors have been considered easier to remove; the authors, however, keenly observed that soft tumors with microcysts are not amenable to an easy excision with the suction maneuver, as they envelop cranial nerves and blood vessels and their thin capsule is difficult to dissect from the surrounding arachnoidal membrane. Total excision of these tumors, therefore, were fraught with the risk of injuring these structures.[12],[18],[19],[20] Though this fact is not expressed in great details in the literature, surgery on VNs with a predominance of Antoni B cell population and cystic VNs are associated with slightly higher complication rates, as had also been observed by BRM and his colleagues. He also made the following insightful statement in his paper: Partial excision, that is, intracapsular removal alone, carries a high morbidity and an equally high mortality; and, total excision carries the risk of greater mortality and more immediate postoperative complications, but the improvement after a few months is remarkable. He observed that irrespective of the size of the tumor, there is always an arachnoidal plane separating the tumor from the surrounding neurovascular structures. A meticulous dissection of the tumor capsule and preservation of lower cranial nerves are of paramount importance for achieving a better quality of life.[20] Attempts at total excision of the tumor and the maneuver of opening up of CSF pathways has lead to better postoperative results and a longer survival. In his candid opinion, however, for all practical purposes, in case a proper plane of cleavage was not available, a subtotal excision with the idea of performing a 'second look' surgery is preferable to endangering the life of the patient by always insisting on total excision of the tumor.[19]

At this juncture, special mention must be made of the tumor capsule-arachnoidal relationship of a VS, aptly described by Yasargil.[28],[29],[30] Various articles have highlighted the controversy between the epi- or subarachnoidal origin of the tumor.[28],[31] However, irrespective of its location in relation to the arachnoidal membrane, the first essential step during tumor decompression is to peel off the double layers of arachnoid from the posterior surface of the tumor, followed by its intracapsular subarachnoidal decompression. The senior author of the present article (SKG) believes that the true surgical plane lies in between the true VS capsule and the infolded arachnoidal layer (that is, outside the two distinct arachnoidal layers).[31] By maintaining a complete “extra-arachnoidal dissection” of the tumor, there are practically no chances of sustaining a neurovascular injury as the vital neurovascular and cranial nerve structures remain inside the layers of the arachnoid.[31] In nearly all the cases, safe dissection can be achieved from the brain stem, lower cranial nerves, and the fifth nerve by practicing a meticulous dissection. Sudhir et al., have emphasized that the key element in performing successful surgery for a VS is in understanding that the flattened facial and cochlear nerves do not have an arachnoidal layer separating them from the tumor capsule. The junction is essentially the compressed and attenuated perineurium of the vestibular nerve from which the tumor has grown. If the tumor cannot be dissected from the facial nerve easily, a sub-perineural dissection is advisable under facial nerve monitoring to prevent nerve injury.[28],[31] In the case of an arachnoidal breach, every attempt should be made to prevent blood from entering between the arachnoidal layers as it may lead to an inadvertent brain bulge and tumor bed hematoma. Hemostasis should be achieved with the minimal use of bipolar coagulation, with the gentle application of compression over the bleeding area on the tumor bed.[31]

This article by BRM et al., aptly identified the need for mastering the nuances of neuro-otological surgery as an extension and refinement of general neurosurgical principles. Before embarking upon this journey, the neurosurgeon is expected to have a good understanding of the three-dimensional anatomy of the cerebellopontine angle and the temporal bone. The person should be well-versed with the necessary skill sets needed for drilling the temporal bone, for handling brain tissue in this crowded neurovascular neighborhood and for securing an effecting haemostasis.[12],[18],[19],[20] Special mention should be made regarding the forward and backward rotating drills, as drilling should be performed away from the nerve. Advanced drilling systems have differential drilling speeds, which should be judiciously utilized based upon the proximity of vital structures. One should always drill with the side rather than the tip of the drill while remaining parallel to the important structures. Copious saline irrigation should be used to avoid any thermal injury and clogging of the suction apparatus.[32] The internal auditory canal should be uncovered over 270 degrees rather than 180 degrees. Utmost care should be exercised while drilling the meatus to avoid any accidental slip, thermal injury or plunging of the burr into the surrounding structures, especially the jugular bulb.[31] Rather than a complete drilling of the internal auditory canal, a limited drilling with resection of the meatal component of the tumor under neuro-monitoring guidance is preferable. The superior and inferior borders of internal auditory canal should be carefully identified before embarking upon the removal of the posterior lip, as drilling of the latter increases the chances of sudden entry into the internal auditory canal and of damage to the cranial nerves within the canal. Removal of enough bone superior to the internal auditory canal is essential to get a good visualization.[32] The drilling on the inferior surface of the posterior lip should be done with utmost caution to prevent accidental injury to the jugular bulb.[32],[33]

Outcome assessment

Before this article by BRM et al., was published, the focus among general practitioners was to delay surgery for VSs until the patient became significantly symptomatic. This wrong practice was continued despite reports from the West that operating on a smaller tumor carried lesser morbidity and mortality than operating on a larger one. In the Indian scenario, publication of this article sensitized the masses to the fact that surgery for a VS could be undertaken safely, contradicting the prevailing pessimism among the masses. Subsequent to this era, the introduction of microneurosurgery, auditory brain stem evoked potentials and intraoperative monitoring has further helped in functional preservation of cranial nerves while drastically reducing the mortality rates of the procedure.[27]

BRM et al., were strikingly honest in reporting their complications and mortality rates. The mortality reported in their series was approximately 23%, which was definitely higher than that experienced in the present era but was significantly better than that reported in the contemporary surgical series of that time.[12],[23],[24],[25],[34] It has been stressed that a significant number of these patients died because of a deficient postoperative care. The influence of this factor on mortality has been considerably mitigated in the modern times. In the last decade, the focus of surgery has shifted from achieving total surgical removal to performing function preserving surgery. Remarkably gifted surgeons like Madjid Samii still advocate total surgical removal with anatomical visualization and preservation of facial nerve with impressive clinical results related to functional preservation of the facial nerve.[34],[35] However, in most of the large series on VSs, the rate of functional preservation of the seventh nerve in patients with a large or a giant VS remains in the range of 40-50%. Series reporting better preservation rates of up to 80-90% are also available but a careful evaluation of these series reveal that they have also included smaller tumors in their analysis.[36] The advent of gamma knife radiosurgery (GKRS) and other forms of stereotactic radiosurgery (SRS) has also been a game changer. In the current day neurosurgical practice, in patients with VSs <3 cms in size and in the absence of any major neurological deficits other than cranial nerve deficits, GKRS has become the standard of care. For patients with larger tumors, the issues related to facial nerve preservation and partial versus total removal remain as relevant today as they were five decades ago. There have been articles citing the so called 'hybrid approach', which entails a planned partial resection akin to the intracapsular removal ( first reported by Cushing almost a century ago and also discussed in the paper by BRM et al.,) followed by SRS/GKRS.[37] However, neuromonitoring of the cochlear nerve could not lead to improvement in functional preservation of the vestibulocochlear nerve, as had been observed for facial nerve preservation.[38] The preservation of neurological function is the predominant theme of today's management, as the focus has now shifted from life-saving to function preservation surgery. In the pre-microsurgery era, the majority of patients were tracheostomised after excision of a VS; however, this rate decreased significantly with more surgical experience and with advancements in the surgical armamentarium.[12],[18],[19],[20] Much of the morbidity reported in the article by BRM et al., was possibly related to occurrence of venous injury as well as due to coagulation of the arachnoidal layer during dissection outside the tumor capsule, which resulted in loss of the arachnoidal plane. Remaining extra-arachnoidal during tumor excision with preservation of the veins surrounding the tumor has made a significant impact in reducing the postoperative morbidly and mortality.

As an extension of his continued efforts in getting better results during surgery for a VN, BRM described his technique of 'two stage excision of acoustic neurinomas' in the August 1980 edition of the Journal of Neurosurgery, and his overall experience gained over 43 years in the managment of VSs in the British Journal of Neurosurgery. Due to his continuous efforts, in the latter half of his career, he could achieve outstanding results with an overall mortality of 4% with large VSs, and a mortality of 1% with small VSs. The recovery of facial nerve was observed in only 10% of his patients with large tumors though these figures kept on improving.[20] Thus, by an assiduous maintenance of an audit and a meticulous record of his own cases, and by continuously striving towards self-improvement, BRM and his colleagues have served as role models for the modern surgeons to emulate.

Role of radiosurgery

The history of surgery for VS runs parallel to that of microneurosurgery. The next landmark advancement in this field in the last two decades was achieved by the introduction of radiosurgery in the management of VSs. In present era, no discussion regarding the management of a VS can be completed without mentioning the stellar role of radiosurgery. At the time of publication of the article by BRM et al., radiosurgical facilities were not available in India. The traditionally documented indications for radiosurgery included their administration in patients who were elderly, medically infirm, patients with bilateral tumors, tumor on the side of the only hearing ear, and in patients who refused open surgery. With the advent of magnetic resonance screening of communities, the incidental detection of VSs has significantly increased. This has increased the chances of detecting patients who are suitable candidates for hearing and facial preservation surgery. A Rotterdam based population study has reported the incidence of an asymptomatic VS in 1 in 500 individuals.[39]

An ideal candidate for GKRS for VS is a young patient with a small or medium-sized tumor with either no manifestations or minimal symtoms related to the compressive phenomena produced by the tumor. Patients with Koos grade 1-3 are good candidates for primary GKRS. Patients with a large VS should be ideally managed by a planned partial intracapsular resection with VII and/or VIII nerve functional preservation, performed under physiological cranial nerve monitoring, with the subsequent administration of adjuvant radiosurgery.[40]

Various radiosurgical series have reported their results of primary radiosurgery for Koos grade 4 VSs and cystic VSs, though the tumor control rate and functional preservation in these patients remain equivocal. The Pittsburgh group has advised that the patient should wait for 6 months to an year in case facial paresis of House-Brackman grade 2 or more develops after surgical resection of a VS. This is to facilitate spontaneous recovery prior to administering radiosurgery; it results in better facial nerve preservation in comparison to the results obtained when radiosurgery is administered immediately after tumor resection.

It would not be an exaggeration to state that these visionary neurosurgeons who combined as a team to publish this seminal paper on surgery for a VS had very realistic expectation of overcoming the problems that they encountered in the management of patients with a VS. They still proposed viable solutions in the pre-microsurgical era that have withstood the test of time and remain relevant in the present era. The article written by BRM et al., was a classic one, as aptly justified by Italo Calvino, “A classic is a work which relegates the noise of the present to a background hum, which at the same time the classics cannot exist without.” The experience shared in this article guided several generations of neurosurgeons and boosted their confidence while performing the complex surgical procedure of VS excision.

[Additional file 1]

 
  References Top

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