Figure 1. Staging technique performed with the aid of ring-ended grasping forceps. (From Microneurosurgery, Vol. 1; Yasargil)
Figure 2. In order to secure all the aneurysm base into the clip, a stepwise "staging" clip application is necessary. (From Microneurosurgery, Vol. 1, p. 261; Yasargil)
I very much appreciate being asked by the AANS Archives to discuss my thoughts regarding my personal involvement in the development of aneurysm surgery. In order to relate the contribution of microsurgical techniques to this field, I would initially like to briefly illuminate the evolution of the diagnosis and treatment of this terrifying and still obscure disease.|
The clinical recognition ot intracranial aneurysms was slow in its evolution. The very first cases were reported in the 18th Century (Morgagni, Biumi, Hunter). In 1814 Blackhall published a verified report of a ruptured aneurysm. Horsley (in about 1885) made the diagnosis of a giant intracranial aneurysm prior to surgery and performed ligature of carotid arteries. Quincke in 1891 described the use of lumbar puncture in connection with diagnosis of intracranial bleed. The 20th Century was ushered in by the introduction of a test which could confirm the presence of a subarachnoid hemorrhage. In the time period between 1885-1935 ligature of the carotid artery in the neck was advocated as a possible successful treatment mode.
Between 1935-1950 cerebral angiography was accepted as a valuable diagnostic tool to visualize aneurysms. The clinical symptoms and signs of ruptured, as well as unruptured aneurysms, were systematically studied as a special entity of this disease of the CNS. The early pioneers of neurosurgery were challenged to attempt more courageous interventions such as intracranial ligation of the aneurysm, wrapping of the aneurysm sac, and even the elimination of the aneurysm by applying a clip (Dandy).
Scientific and technical advances between 1950-1970 promoted innovations in Neuroradiology (transfemoral serial angiography, stereoscopy, subtraction and tomo-angiography); in Neuroanesthesia (intubation-anesthesia, induced hypotension and hypothermia, control of blood-gases and salt-fluid regulations); in Neuroscience (EEG, radioisotopes for scintigraphy to ascertain general and regional cerebral blood flow, and for measure the circulation time of the CSF); and in Pharmacology (diuretics and steroids). The achievements in cerebral angiography enabled the neurosurgeon to analyze, on a large series of cases, the angiographic details of intracranial aneurysms including site, size, shape, number of aneurysms as well as the configuration and condition of the collateral Circle of Willis. The presence of arterial vasospasm, hydrocephalus, and mass effect from hematomas could be appreciated.
The consequences of a SAH were systematically studied and related to the clinical condition of the patient, which was classified on a grading scale. The time of surgery came to be a main topic for discussion with the general acceptance of the rule that the operation for a ruptured aneurysm should be delayed for at least three weeks. Various surgical approaches were developed (subfrontal, subtemporal, suboccipital and interhemispheric). A range of aneurysm clips were introduced including types that could be adjusted or removed after initial placement. To control the hemodynamic environment during exploration and clipping of an aneurysm the patient was placed in a state of induced hypothermia but this technique was soon abandoned because of the many postoperative complications; on the other hand induced hypotension found general acceptance. The tactics of surgery consisted of a direct line of approach targeting primarily the aneurysm using manual retraction by one or two assistants on the frontal or temporal lobes or cerebellar hemisphere; and occasionally even resorting to partial or subtotal resection of a lobe. The aneurysm-sac was dissected from the overlying tissue (hematoma, brain tissue or both) until the application of a clip to the exposed aneurysm seemed feasible.
In the event of premature rupture of the aneurysm, controlled surgical dissection could be lost. Such a situation required great experience and expertise from the surgeon in order to overcome the life-threatening situation. If the parent vessels in the vicinity of the aneurysm could have been dissected and prepared beforehand, for such an event, they could be temporarily or permanently clipped and the devastating bleeding brought under control before vascular distention of the brain occurred.
As a last resort, trapping techniques could be applied, sacrificing perforators whose importance were not fully appreciated at that time. Early on in cerebrovascular surgery the number of neurosurgeons who developed a mastery in effective surgical treatment of aneurysms with remarkable low morbidity and mortality (5%) remained few. The surgical treatment of intracra-nial aneurysms could not be established on a broad basis and remained, in general, a feared and hazardous, and thus highly respected procedure.
The accelerating technical and scientific advances as well as the engagement of industry opened a new era (1970-1990) with the introduction of new diagnostic tools-computerized tomography, magnetic resonance imaging (MRI, MRA, func-tional MRI), SPECT, PET, DSA, 3D CT angiography, and superselective catheterization for cerebral angiography, and, as therapeutic options endovascular occlusion of the aneurysm with balloon or electrocoil techniques and microsurgical illumination of the aneurysms.
Microsurgical techniques offer to the surgeon a great improvement in working conditions to achieve the effective surgery of the intracranial aneurysms and an improved outcome for the patients.
Microsurgery, however, requires a clear definition: it is not just the sole use of a microscope during a conventional neurosurgical exploration. It is an entirely new surgical discipline and concept requiring the use of a mobile counter-balanced operating microscope, and necessitating mastery of indirect eye-hand interaction which can only be acquired in a specially equipped laboratory.
Microneurosurgery constitutes two main components:
- Special armamentarium
- Counter-balanced mobile operating microscope equipped with a mouth-switch which allows free bimanual surgical manipulations during the entire procedure and T.V. camera and monitors to enhance and promote team work in the operating room between surgeon, neuroanesthesiologist, nurses, and technicians.
- Bipolar coagulators and bipolar forceps of different lengths and tip size.
- Pressure regulated suction apparatus and suction tubes in different lengths and diameters.
- Bayonet-shaped surgical instruments in different lengths and tip sizes and malleable microinstruments.
- Variety of temporary and permanent aneurysm and vessel clips and applications. There are now 180 different clips available.
- Microsutures and special needle holders.
- Self-retaining "protective" brain retractors.
- Hydraulic chair and adjustable arm rest for the surgeon.
- Special surgical techniques requiring laboratory training to perfect
- Enhanced eye-hand interaction working under conditions of indirect vision with the operating microscope.
- Delicate manipulation with microinstruments during dissection, clipping, coagulating, neurovascular repair, and grafting.
- Tactics to operating within a key-hole approach performing the procedures as mentioned in 2. B.; but, under more difficult conditions, for example plastic boxes of different heights (5-12 cm) and with narrow openings cm diameter) simulate deep narrow approaches within and around the brain.
- Delicate and controlled manipulations within the confines of a small gap and using a self-retaining protective brain retractor.
- Training the use and applications of the bipolar coagulator and microsuction equipment.
- Exercises for the creation of an aneurysm and arteriovenous fistula on the carotid artery or aorta of a laboratory rat; practicing the technique of application of temporary and permanent clips and the technique of bipolar coagulation to shrink the different parts of the created vascular anomaly, to form in the case of an aneurysm, a suitable neck from the original wide base, which is more amenable to precise placement of a clip.
- Training to develop expertise and comfort using high-speed surgical drills.
My personal experience in developing and promoting new and improved surgical techniques for aneurysm surgery encompassed the following:
- The introduction and regular consistent application microsurgical techniques in the treatment of intracranial aneurysms on 2090 patients (2784 aneurysms) between 1967 and 1992.
- The introduction of the counter-balanced mobile operating microscope with mouth-switch, enabling the surgeon to perform the entire surgical procedure bimanually.
- The development and introduction of microsurgical and microvascular techniques:
- "Keyhole" approach along the arachnoidal (c)sternal) pathways of the brain allowing an indirect exploration of the aneurysm without retraction of the brain.
- Pterional-transsylvian approach for the exploration of carotid, middle cerebral, anterior communicating, and basilar up aneurysms.
- Microdissecuon in a small, narrow, and sometimes deep (10 cm), gap.
- Development and introduction of self-retaining protective brain retractor.
- Development and introduction of bayonet-shaped instruments (bipolar forceps, scissors, dissectors).
- Development and introduction of a range of temporary and permanent vascular clips.
- In order to prevent a film of moisture (fogging) developing on the surface of the eyepieces, an electric hearing cable has been attached around the binocular tubes.
- Introduction of 2D and 3D TV cameras to coordinate the surgeons, neuroanesthesiologist, operating room nurses,and technicians into a well-orchestrated team.
- Microsuraical exploration of the anatomy of the Circle of Willis, parent artery (arteries), and perforators.
- Microsurglcai exploration ot the anatomy and geometry of aneurysms, their relation to adjacent structures (aura, arachnoidea, pie, parent arteries, and perforators).
- Full appreciation of the importance of perforators. No clip was applied before the involved perforators had been identified with certainty and dissected free and secure their preservation before application of a clip.
- Introduction of the technique of shrinking an aneurysm using bipolar coagulation. Most aneurysms have no neck for the proper and exact application of a clip. They have a dysmorphic, large base, which requires creation of a neck applying the techniques of step-wise shrinkage: temporary clips are placed on the parent artery (arteries), the aneu-rysmal sac is opened with microscissors (first punctured with a needle if turgor is observed) and bipolar coagulation applied (low setting at first) to shrink the sac, seal the edges, and create a suitable form for the application of one clip.
- If necessary (sclerotic aneurysm) performance of resection of the aneurysm and closure of the orificium with microsutures.
- Introduction of extra-intracranial by-pass technique (extra-intracranial bypass between superficial temporal artery and a temporal pial artery).
- to support the collateral blood flow
- enable ligation of the parent artery in case of non-clippable very large based aneurysms
- Exploration and clipping of multiple (unilateral and/or bilateral) aneurysms via the same approach or combined approaches (22% of parents presented with multiple aneurysms).
- Papaverine application and sympathectomy to the explored arteries, to prevent intra- and post-operative spasm of explored arteries.
- Removal of hematomas in the basal cistern to prevent post-operative arterial spasm and opening of the lamina terminalis for the treatment of hydrocephalus reduced the rate of post-operative hydrocephalus from 8% to 3 %.
- The surgery has been performed throughout the past 25 years in normotension, normothermia, normovolemy, and without the use of any Calcium-Channel blockers.
Preoperative Condition as Related to Surgical Results
in 2050 Patients (1967-1992)
|Grade||No. of Cases||Good||Fair||Poor||Death|
|Oa||23 (1.1%)||22 (95.7%)||--||--||1 (4.3%)|
|Ob||85 (4.6%)||70 (82.4%)||6||4||5 (5 9%)|
|I||547 (26.2%)||534 (87.6%)||11||1||1 (0.2%)|
|II||1082 (51.8%)||1020 (94.3%)||41||9||12 (1.1%)|
|III +||273 (13.1%)||195 (71.4%)||42||14||22 (8.1%)|
|IV +||57 (2.7%)||12 (15.0%)||10||18||17 (29.8%)|
|V +||23 (1.1%)||-||1||5||17 (73.9%)|
|Ob= unruptured-symptomatic aneurysm cases|
|+= patients operated due to hematomas or hydrocephalus. Delayed ischemic lesions occurred in 3 % of cases|
Surgical Results Only in Grade Oa, I and II
|Grade||No. of Cases||Good||Fair||Poor||Death|
|Oa-I-II||1652 (79.0%)||1576 (95.4%)*||52 (3.1%)||10(0.6%)||13 (0.8%)|
|* 90% returned to former profession, 10% reached retirement age and were no longer working.|
- In the early phases of consequent microsurgical treatment of aneurysms in Zurich (1967) the general view was held that this meticulous approach was impressive, but there remained an obsessive fear that, should premature rupture of an aneurysm occur, the surgeon would have greater difficulty to control the situation in a small gap than in a large exploration. Experience proved that this was not the case. The delicate and dangerous situation of a premature rupture of an aneurysm could usually be efficiently managed as the parent arteries had always been explored before-hand; therefore allowing the application of temporary clips to the involved parent arteries under controlled hemody-namics. The microsurgical treatment of intracranial aneurysms had become a coherent and structured procedure which could usually be accomplished within 90-120 minutes (skin to skin).
- The timing of surgery is not related to the elapsed time since hemorrhage, but to the quality of consciousness of the patient and since 1967 the patients in Grade I and II were explored immediately. This changed the previous concept of a "three week waiting period", and in the beginning, this new regime was opposed. The patient in Grade III, IV, and V were explored immediately if their poor condition could be related to the large symptomatic hematomas (c)sternal, intracerebral, interhemispheric, or combined) or to the subacute hydrocephalus. However, the patients in grade III, IV, or V without hematoma or hydrocephalus were only operated if they recovered and reached the condi-tion of Grade I or II. The morbidity rate of these patients in Grade III-V in waiting period was 1.1 % (23 cases).
Timing of Surgery in Cases with Ruptured Aneurysms
Nowadays, this last group of patients (Grade III-IV), especially those with severe spasm, can possibly be helped with endovascular prophylactic occlusion (electrocoil) of the aneurysm and application of angioplasty.
Another essential problem remains that 30-50% of patients with a ruptured aneurysm die before reaching the hospital. A concept for establishing a diagnosis of silent aneurysms and initiating appropriate treatment before the catastropic event can take place is the challenge that accompanies neurosurgeons to in the 21st Century.
An abstract of the oral history of Dr. Yasargil is available.