J Neurosurg 72:546-553, 1990

Percutaneous microcompression of the gasserian ganglion for trigeminal neuralgia RAMIRO D. LOBATO, M.D., JUAN J. RIVAS, M.D., ROSARIO SARABIA, M.D., AND EDUARDO LAMAS, M . D . Service of Neurosurgery, Hospital "1~ de Octubre, " and Faculty of Medicine, Universidad Complutense, Madrid, Spain ~" The authors report 144 cases of trigeminal neuralgia treated by percutaneous microcompression of the trigeminal ganglion (PMTG). The operation was performed under short-lasting barbiturate anesthesia without endotracheal intubation. Meckel's cave was cannulated with a No. 4 Fogarty catheter and the balloon was inflated for 1 minute. The average intraluminal pressure required for adequate compression of the ganglion was about 1200 mm Hg. All patients were initially relieved of their neuralgia. In a follow-up period ranging from 6 months to 4 89years, 14 patients (9.7%) developed recurrence of pain between 10 and 35 months after surgery. Eleven patients underwent a second PMTG. All nine early failures and t0 of the 11 late recurrences occurred in cases with technical deficiencies. Most of the minor surgical complications observed were also related to avoidable technical errors. There were no anesthetic complications and no deaths. All patients developed mild to moderate postoperative hemifacial numbness with or without objective hypesthesia. Both subjective and objective deficits gradually diminished with time and were well tolerated. One year after the operation nearly 40% of the patients still had patches of slightly decreased sensation in one or more trigeminal divisions and 16% had mild dysesthesia. Anesthesia dolorosa or keratitis was not reported. The PMTG procedure is easy to perform and requires a short operative time and a brief period of hospitalization. It is well tolerated by patients, who describe it as a totally pain-free experience. Morbidity is minimal and recurrence of neuralgia does not seem to be higher than with alternative procedures. KEY WORDS trigeminal nerve 9 trigeminal neuralgia percutaneous microcompression 9 balloon compression *

I

S the 1950's a n d t 9 6 0 ' s deliberate compression o f the gasserian ganglion was p e r f o r m e d t h r o u g h an open operation for the treatment o f trigeminal neuralgia, j'9'23'26'34 Percutaneous mechanical gangliolysis was also performed either by massaging the ganglion with a blunt instrument 13 or by a fairly rapid injection o f saline solution into Meckel's cave. 7 It was not until 1983 that Mullan and Lichtor ~7 described a safe and effective m e t h o d for compressing the ganglion using an inflatable balloon. Their preliminary results were promising e n o u g h to warrant its application in larger series o f patients. Yet the operation required general anesthesia with endotracheal intubation, and the optimal c o m p r e s s i o n parameters to achieve a minimal sensory deficit with a low recurrence rate had to be defined. We analyze o u r experience with percutaneous m i c r o c o m p r e s s i o n o f the trigeminal ganglion ( P M T G ) in 144 patients operated on u n d e r short-lasting barbiturate anesthesia. 546

9 gasserian ganglion

9

Clinical Material and Methods Patient Population Between October, 1984, a n d October, 1988, we treated 144 consecutive patients by P M T G . Three patients in w h o m Meckel's cave could not be cannulated subsequently u n d e r w e n t microvascular decompression (two cases) or radiofrequency (rf) coagulation (one case), and four m o r e patients were initially cured but lost to follow-up review; these seven cases were not included in the series. T h e patients' sex and age, trigeminal division affected, p r e s u m e d etiology o f neuralgia, preoperative neurological findings, and previous surgical treatments are displayed in Table 1. T w e n t y - f o u r (16.7%) patients were 50 years o f age or under. Fifty percent o f the patients h a d pain involving the ophthalmic or multiple trigeminal divisions. F o u r patients (2.8%) had bilateral neuralgia; o f these, three had had rf coagulation a n d one a Frazier operation on the J. Neurosurg. / Volume 72/April 1990

Gasserian ganglion microcompression for trigeminal neuralgia TABLE 1

Clinical summary of 144 patients treated by percutaneous microcompression of the gasserian ganglion* Factor

Cases No.

%

58 86

40.3 59.7

1 7 16 36 40 30 13 1

0.7 4.7 11.1 25 27.8 20.8 9 0.7

5 33 39 14 52 1 4

3.5 22.9 27.1 9.7 36.1 0.7 2.8

138 3 1 1 1

95.8 2.1 0.7 0.7 0.7

21 43 3 5 6

14.6 29.9 2.1 3.5 4.2

86 45 9 2 2 2

59.7 31.2 6.2 1.4 1.4 1.4

sex

male female age (yrs) --< 30 31-40 41-50 51-60 61-70 71-80 81-90 > 90 affected trigeminal division V1 V2 V3 V~+2 V2+ 3 Vl+2+ 3

bilateral presumed etiology idiopathic neuralgia multiple sclerosis megadolichobasilar posterior fossa AVM posterior fossa meningioma prior surgical treatment peripheral nerve blocks rf thermocoagulation microvascular decompression Frazier operation other]" neurological examination normal V sensory deficit VIII VII VI IX, X

FIG. 1. Lateral radiographs showing a n appropriately placed balloon inflated with c o n t r a s t agent u n d e r different pressures. Upper." M o d e r a t e d i s t e n t i o n without herniation toward the posterior fossa ( i n t r a l u m i n a l pressure 700 m m Hg). T h e sensory state b e c a m e completely n o r m a l within 1 week of surgery a n d the p a t i e n t is still free of neuralgia 1 year after the operation. Center: P e a r - s h a p e d balloon with a nipple protruding t h r o u g h the p o r u s trigemini (intraluminal pressure 1150 m m Hg). This was the configuration most comm o n l y seen in this series. Lower: M a r k e d herniation caused by very high i n t r a l u m i n a l pressure (1700 m m Hg). This resulted in an u n u s u a l intense hemifacial numbness.

* AVM = arteriovenous malformation; rf = radiofrequency. Roman numerals indicate cranial nerves. One patient operated on for an acoustic neurinoma and another suffering severe head injury had cranial nerve deficits. The patient with megadolichobasilar and another with idiopathic neuralgia had ipsilateral hemifacial spasm. t Includes glycerol injection, balloon compression, and alcohol block performed at other clinics.

neuralgia after rf coagulation who were included in the present study were from our personal series of 245 cases t r e a t e d b e t w e e n 1977 a n d 1984. N e a r l y o n e - t h i r d o f the patients had some residual facial sensory deficit before undergoing PMTG.

Anesthetic Technique c o n t r a l a t e r a l side. All b u t six p a t i e n t s h a d i d i o p a t h i c t r i g e m i n a l n e u r a l g i a a n d all w e r e r e f r a c t o r y to, o r i n t o l e r a n t of, c a r b a m a z e p i n e . A l a r g e n u m b e r o f p a t i e n t s (43%) had had one or more surgical procedures before undergoing PMTG. Most patients with recurrence of

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Patients were premedicated while on the ward to p r o v i d e m i l d s e d a t i o n . A t r o p i n e , d r o p e r i d o l , a n d fentanyl were administered in the operating room. Skin puncture, entrance to the foramen ovale, and ganglion compression are performed under short-lasting anes547

R. D. Lobato, J. J. Rivas, R. Sarabia, and E. Lamas

FIG. 2. Lateral (left) and anteroposterior (righO radiographic projections in patients with satisfactory (upper) and inadequate (lower) placement of the Fogarty catheter. When the balloon protrudes into the cave

it projects at the apex of the petrous bone in the anteroposterior view and its axis forms an angle of about 45 ~ to the sagittal plane (upper right). A balloon fully distended into the temporal fossa out of the cave is shown

(lower).

thesia induced by sodium thiopental or, less frequently, etomidate. Endotracheal intubation was not carried out. Oxygen was given via nasal prongs and the heart rate and blood pressure were monitored throughout the procedure. To counteract increases in blood pressure induced by ganglion compression, patients received a bolus o f sodium nitroprusside just before balloon distention.

Operative Technique We performed 164 procedures in 144 patients (nine were repeat operations on early failures and 11 were late recurrences). For this technique, the patient is positioned supine and the head is kept in a neutral position throughout the procedure. A C-arm intensifier fluoroscope is used. The point of entry into the skin is 2 cm external and 0.5 cm superior to the angle of the mouth. A No. 14 needle is initially advanced parallel to the sagittal plane in order to avoid transfixion of the oral mucosa, and then it is redirected under fluoroscopic guidance until the foramen ovale is entered. 548

Penetration beyond foramen margins is avoided. A No. 4 Fogarty catheter with its fine steel stylet is introduced until 10 to 12 m m of catheter lies beyond the needle tip. Mild resistance is usually encountered before entry into the cave. Following stylet withdrawal, the balloon is inflated with 50% Conray contrast-medium under lateral fluoroscopic control until it begins to protrude toward the posterior fossa. The shape and position of the balloon are checked with respect to neighboring bone landmarks (clivus, sella, and petrous bone); if not correct, the balloon is immediately deflated and the catheter is repositioned until the ideal pear-shape appearance is achieved with a small nipple protruding into the posterior fossa through the porus trigemini (Fig. 1). Anteroposterior fluoroscopy m a y help to define the location of the balloon when its shape is not fully typical on the lateral projection (Fig. 2). Following ganglion compression for 1 minute, the contrast medium is aspirated, the catheter is withdrawn, and the puncture site is compressed manually for a few minutes. Since functional localization is not needed, the proce-

J. Neurosurg. / Volume 72/April, 1990

Gasserian ganglion microcompression for trigeminal neuralgia TABLE 2

Operative details in 144 patients treated by percutaneous microcompression of the gasserian ganglion Cases

Factor balloon shape pear-shaped "hourglass" oval round irregular balloon volume 0.5 ml 0.6 ml 0.7 ml 0.8 ml 0.9 ml 1.0 ml 1.1 ml time of compression 3 min 2 min 1.5 min 1 min

No.

%

117 9 9 5 4

81.2 6.2 6.2 3.5 2.8

2 2 26 58 34 19 3

1.4 1.4 18 40.3 23.6 13.2 2.1

2 7 9 126

1.4 4.7 6.2 87.5

d u r e is usually c o m p l e t e d w i t h i n 15 minutes. Patients are discharged the d a y after t h e o p e r a t i o n . F o r the p u r p o s e o f d o c u m e n t a t i o n , we o b t a i n e d biplane r a d i o g r a p h s in t h e m a j o r i t y o f cases. In an att e m p t to s t a n d a r d i z e t h e m o s t suitable c o m p r e s s i o n force we m e a s u r e d i n t r a l u m i n a l b a l l o o n pressure d u r i n g c o m p r e s s i o n in 22 cases.

Results

Balloon Shape, Inflation, Volume, and Duration o f Compression T a b l e 2 reflects the shape o f t h e b a l l o o n as seen in the lateral r a d i o g r a p h i c p r o j e c t i o n , t h e v o l u m e injected, a n d the d u r a t i o n o f c o m p r e s s i o n at the first P M T G . U s u a l l y the cave was c a n n u l a t e d at the first a t t e m p t ; however, in 18% o f the cases c a n n u l a t i o n was initially unsuccessful as i n d i c a t e d b y t h e i n a p p r o p r i a t e shape a n d p o s i t i o n o f the b a l l o o n , a n d t h e c a t h e t e r h a d to be r e p o s i t i o n e d o n e o r m o r e t i m e s u n t i l the characteristic p e a r shape a p p e a r e d . In eight p a t i e n t s (5.5%), as the b a l l o o n was inflated it m i g r a t e d i n t o the posterior fossa before an a d e q u a t e pressure was r e a c h e d in the cave (Fig. 3). T o c o u n t e r a c t s p o n t a n e o u s b a l l o o n m i g r a t i o n t h r o u g h the p o r u s t r i g e m i n i , we w i t h d r e w the catheter slightly while injecting the v o l u m e necessary to c o m press the ganglion. A s u d d e n decrease in c o m p r e s s i o n force, p r o b a b l y related to d i s r u p t i o n o f the ganglion d u r a l sheath b y the i n f l a t e d b a l l o o n , o c c u r r e d in four cases; e n l a r g e m e n t o f t h e b a l l o o n ' s c o n t o u r s with def o r m a t i o n o f the initial a p p e a r a n c e was observed u n d e r fluoroscopic c o n t r o l in these patients, w h o d i d not suffer p o s t o p e r a t i v e c o m p l i c a t i o n s . In 18 p a t i e n t s (12.5%) the b a l l o o n a d o p t e d a n oval, r o u n d , o r irregular shape in a l o c a t i o n a s s u m e d to be c o r r e c t o n the basis o f the

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FIG. 3. Sequential radiographs showing spontaneous migration of the balloon into the posterior fossa. The Meckel's cave:porus trigemini vertical diameter ratio as measured in the lateral projection was only 1.6 in this patient, while it averaged 2.8 in the series. Upper." Before adequate pressure could be reached in the cave, the balloon began to herniate through the porus (volume of inflation 0.65 ml; pressure low). Center and Lower. Additional injection of contrast material did not increase the intraluminal pressure but caused progressive migration toward the posterior fossa. Complete migration occurred with 0.85 ml (not shown). To achieve satisfactory ganglion compression the catheter was withdrawn slightly while the balloon was distended, thus preventing complete migration into the posterior fossa.

549

R. D. Lobato, J. J. Rivas, R. Sarabia, and E. Lamas

FIG. 4. Upper: Repeated balloon inflation at the initial operation in this patient always resulted in an oval shape. The filling defect in the anterior part was due to air within the balloon. In spite of adequate intraluminal pressure, the balloon did not protrude toward the posterior fossa. Postoperative hemifacial numbness lasted for only a few days, but the patient was free of neuralgia for 1 year. Lower: At reoperation following recurrence, a pear-shaped balloon was seen and the patient experienced more lasting hemifacial numbness. radiographic appearance. The small nipple protruding toward the posterior fossa cisterns was not clearly visible in these cases, but the balloon never adopted the cylindrical form observed when it is inflated in the middle or posterior cranial fossa (Fig. 4). The balloon volume necessary to achieve adequate ganglion compression ranged from 0.6 to 1.1 ml. Pressure within the fully developed pear-shaped balloon measured in 22 patients ranged between 980 and 2080 m m Hg (average.+_ standard deviation: 1200 + 240 m m Hg). As could be expected, the volume that was needed to reach a given pressure varied from patient to patient depending on the size of Meckel's cave. However, the intensity and duration of postoperative hemifacial numbness were different in patients sustaining similar pressure inflation. Pressure below 600 m m Hg cannot be expected to yield any therapeutic effect. Compression lasted 60 seconds in m o s t cases. Early in our series we realized that, once an appropriate pressure is reached, this compression time suffices to elicit a good functional result, which limited the duration of compression-related cardiovascular instability. 550

Intraoperative and Immediate Postoperative Complications There were no anesthetic complications. Venous or arterial bleeding through the cannula was observed in 16 (11%) and four (2.7%) cases, respectively. Venous bleeding did not alter the course of operation, but arterial bleeding required repositioning of the needle. One patient had bleeding through the external auditory canal and two m o r e suffered epistaxis. We did not encounter especial technical problems in patients previously treated by rf coagulation or Frazier operation. Sixteen patients (11%) developed herpes simplex perioralis within the first few days of operation. Four patients, all o f w h o m had the balloon inflated out of the cave for 15 to 30 seconds, developed transient diplopia; this condition lasted for 1 to 3 weeks in three cases and for as long as 4 months in one w o m a n who had marked paresis of the sixth cranial nerve. Three of these were early cases in our series treated at a time when we were still unaware of the risk of keeping the inflated balloon out of the cave. Five patients exhibited cheek h e m a t o m a with transient discomfort. Four more patients complained of headache lasting for 1 to 2 days after the operation; one of these had meningeal signs, due to an aseptic meningeal resection and one had pneumococcal meningitis; both conditions were successfully controlled. In the latter case the oral mucosa was perforated during needle insertion. One patient, who was not included in this study because the cave could not be cannulated, developed a low-flow carotid-cavernous fistula which resolved spontaneously in 3 months. Repeated needle insertion with different incidences always resulted in arterial bleeding, probably from the carotid artery. Early Failures An initial failure occurred in nine patients (6.2%), all of w h o m underwent a second operation within 2 to 12 days of their first P M T G . Six of these patients did not exhibit a pear-shaped balloon and none had the characteristic postoperative sensation of hemifacial n u m b ness which follows successful compression; in all, pain recurred on the day of operation. Three more patients showed a pear-shaped balloon but inflation was probably insufficient, as indicated by the discrete protrusion through the porus trigemini; these three patients had postoperative hemifacial numbness lasting for only a few hours, and neuralgia recurred 2 to 3 days after the operation. A second P M T G with correct balloon location and pressure inflation was followed by durable hemifacial n u m b n e s s and long-term pain relief. Intraluminal balloon pressures in a patient with a pearshaped balloon at both the first and the second P M T G were 840 and 1480 m m Hg, respectively. Treatment Results Inflation of the balloon induced a steep increase in blood pressure in almost every patient unless antihyJ. Neurosurg. / Volume 72/April, 1990

Gasserian ganglion microcompression for trigeminal neuralgia pertensive drugs had been administered previously. A few patients had cardiac arrhythmia during the hypertensive response and the rise in blood pressure subsided when compression stopped, reaching baseline levels within 3 to 10 minutes. These cardiovascular changes did not result in any morbidity in our total series of 198 patients treated by P M T G . Sodium nitroprusside administered just before balloon distention markedly reduced or abolished the hypertensive response. All of our patients were initially relieved of their neuralgia and all developed mild to moderate (and occasionally marked) ipsilateral hemifacial numbness. In most cases there was also mild objective hypesthesia including the mucosal portion of the involved divisions. Both subjective numbness and objective sensory deficit, which were well tolerated, progressively diminished with time. However, 1 year after surgery nearly 40% of the patients still had patches o f decreased sensation of varying size located in one or more trigeminal divisions, and only a minority of patients eventually described facial sensory state as completely normal. Marked hypesthesia involving one or m o r e divisions occurred in only six patients (4.1%). Nearly half of the patients who presented sensory deficits after P M T G had some preoperative sensory deficit secondary to previous surgery. The strength of the ipsilateral masseter muscle was almost invariably decreased immediately after the operation. One year after P M T G , 1 2 % of the patients had asymmetrical mastication. Mastication weakness lasted for only a few days after P M T G in a w o m a n with complete paralysis of the contralateral masseter muscle resulting from a Frazier operation performed 20 years earlier. The corneal reflex was transiently diminished in most cases. Neither anesthesia dolorosa nor keratitis was seen. Although residual sensory deficit was not distressing in most cases, 28 patients (19%) complained of disagreeable sensations such as tingling, pulling, itching, or stiffness in one trigeminal division or, more rarely, all three divisions. Except for four patients who reported dysesthesia as seriously annoying, the majority described these sensations as mild. Paresthesias were commonly aggravated by anxiety or stressful situations and in some patients they diminished with time until they eventually disappeared. L a t e Recurrence

The follow-up duration and incidence of late recurrence of neuralgia are shown in Table 3. Five patients died from intercurrent disease 7 to 40 months after P M T G and all remained free of pain until death. There were 14 (9.7%) late recurrences of neuralgia occurring 10 to 35 months after the operation. The longest painfree intervals were observed in three of the four patients who showed a pear-shaped balloon. The balloon shape in the remaining patients was oval (seven cases), round (two cases), or irregular (one case). The duration of postoperative hemifacial numbness was m u c h shorter on the average than in patients without recurrence, and J. Neurosurg. / Volume 72/April, 1990

TABLE 3

Follow-up duration and recurrencefollowing percutaneous microcompression of the trigeminal ganglion in 144 patients Time After Operation (mos)

No.

Cases %

Recurrence*

6-12 13-24 25-36 37-48 49-54

17 28 31 48 20

I 1.8 19.4 21.5 33.3 13.9

0 9 1 4 0

* Patients' age and the duration and distribution of neuralgia were not different than in cases without recurrence. Six patients with recurrence have had radiofrequencycoagulation. 11 of the 14 patients had no residual sensory deficit at recurrence. The balloon adopted the characteristic pear shape in all 11 patients who underwent a second P M T G , and its volume was increased in the four patients with a pearshaped balloon at the initial operation. Postoperative hemifacial numbness was more marked following reoperation than after initial P M T G in all 11 cases. Two patients decided to continue receiving low-dose carbamazepine and one underwent rf coagulation at another clinic. Discussion The results of this series indicate that P M T G is an effective technique for the control of trigeminal neuralgia. It is easy to perform and involves only brief hospitalization. Since the patient's cooperation is not needed for functional localization, the whole procedure is usually completed within 15 minutes. The use of anesthesia without intubation makes P M T G less distressing for patients, who describe it as a totally painfree experience. With an appropriate technique, most of the m i n o r complications observed in our series can be eliminated and up to the present there have been no deaths related to the procedure. Our preliminary results also suggest that the recurrence rate will not be higher than with other currently used techniques. In spite of the technical ease of execution, P M T G m a y pose some practical problems. Entering the foram e n ovale is usually quick and simple, but sometimes there is venous or arterial bleeding through the cannula. Venous bleeding emerging from a properly placed needle m a y arise from a venous sinus crossing the foramen ovale ~2and does not complicate the course of operation. Arterial bleeding m a y arise from the carotid artery or an accessory meningeal artery traversing the foramen ovale. The carotid artery m a y be punctured when the needle is directed anteriorly and medially into the area of the cavernous sinus, and the risk is greater in patients with a primitive foramen lacerum medius, which consists of fusion of the foramen ovale with the foramen lacerum. 22"25 The bone wall separating the trigeminal nerve from the carotid artery m a y be paper-thin or absent. ~1 A tortuous carotid artery m a y pass directly fifil

R . D . L o b a t o , J. J. R i v a s , R . S a r a b i a , a n d E . L a m a s over the foramen ovale, making it impossible to reach the gasserian ganglion without puncturing the artery. 33 When arterial bleeding occurs, the procedure is best terminated and repeated on the following day. Escape of cerebrospinal fluid (CSF) from the cannula indicates that its tip lies beyond the foramen margins but does not necessarily mean that it is in Meckel's cave; CSF m a y flow from the subtemporal subarachnoid space.l~ In two of our patients with escape of CSF, the Fogarty catheter did not enter the cave and it was necessary to reposition the needle. In one case, we were unable to penetrate the foramen ovale. A technical problem not mentioned in the original description of P M T G : is difficulty in cave cannulation; this occurred in 20% of our cases. The catheter may initially become displaced extradurally, subdurally, or subarachnoid into the temporal fossa. Inadequate placement is promptly revealed by the abnormal relation to bone landmarks and by failure of the inflated balloon to adopt the characteristic pear shape seen when it is in the cave. Compression with an oval or irregular-shaped balloon in an apparently appropriate location may be followed by persistent control of neuralgia, but one must be wary of these atypical shapes as most of our cases with this appearance developed late recurrence of neuralgia. Another technical problem arises when inflation of the balloon causes it to migrate extracranially or into the posterior fossa. The first possibility is rather exceptional, but the second is not rare. Spontaneous migration from Meckel's cave, which is poorly distensible, to the posterior fossa cisterns m a y be related to variations in the anteroposterior position of the ganglion and the relative wideness of the porus trigemini. ~2 To deal with this problem we withdrew the catheter slightly while simultaneously injecting it with the volu m e necessary to reach therapeutic pressure within the cave. Endotracheal intubation used by other authors performing P M T G , cited as a disadvantage of this procedure over other percutaneous techniques, 31 was avoided in our patients. Light anesthesia probably resulted in less efficient control of the pain associated with ganglion compression and in the arterial hypertensive response seen in our cases. Acute hypertension, which bears the risk o f cerebrovascular accidents 2~ or cardiac complications, m a y be prevented by adequate doses of sodium nitroprusside or other short-acting vasodepressor agents used for the same purpose in patients treated by rf coagulation. 14,19,27,29 After some experience is gained, P M T G not only is the simplest technique for control o f trigeminal neuralgia, but it is also less risky, provided that both poor placement of the needle tip beyond the foramen ovale margins and prolonged inflation of the balloon outside Meckel's cave are avoided. Wider application of this innovative procedure will largel.y depend on the quality of the functional results and the recurrence rate of neuralgia. An important issue in this respect is whether we can define optimal compression parameters that will 552

yield long-lasting control of neuralgia while producing minimal or even no facial sensory loss, thus eliminating the risk of postoperative dysesthesia. After analyzing our experience, we subscribe to the statement of Mullan and Lichtor 17 that light compression will eliminate dysesthesia but will result in recurrence, whereas firm compression will eliminate recurrences but give rise to dysesthesia. Those authors r e c o m m e n d e d inflating the balloon only until it begins to take on a pear shape rather than to its full size, in order to avoid intense postoperative hemifacial numbness. However, such a policy has usually led to only transient control of neuralgia in our hands. By contrast, a fully developed pear shape almost invariably resulted in longlasting control of neuralgia. The sensory deficit following therapeutically effective compression, although usually discrete, remains unpredictable in the individual patient. Patients sustained similar degrees o f ganglion compression as assessed by the two most reliable criteria (the radiographic picture and measurement of intraluminal balloon pressure) had sensory states ranging from almost normal sensation to the presence of several patches of decreased pinprick and light touch sensation in all three trigeminal divisions. Thus, these criteria, although useful for establishing the level of pain-limiting compression, are not reliable for predicting the degree of postoperative sensory loss, which seems to be dependent on individual anatomical variations as well) 2 Nearly half of our patients who sustained vigorous ganglion compression presented discrete residual sensory deficits to which most adjusted well and mentioned only on direct questioning. The sparing of the corneal reflex in every case and the absence of anesthesia dolorosa suggest that average sensory loss with P M T G is lower than with other "destructive" procedures. 6'8:5"16'18"24'27"28'3~The higher incidence of residual sensory deficit and unpleasant paresthesias in our series of P M T G procedures as compared to others 3'4'8: is probably related to the use of more vigorous compression in our cases. In apparent agreement would be the lower recurrence rate in our series; if we exclude the cases with recurrence in which the balloon did not show the pear shape at the first operation, the recurrence rate would be only 3%, which is quite low for the period of observation. In any case, the actual recurrence rate in the present series is not higher than with other established surgical procedures. Taking into account the incidence of early failures, major and m i n o r complications, and late recurrences with this and other alternative p r o c e d u r e s , 2'5"15"16:8'2~176 w e are currently offering P M T G to virtually all our patients with trigeminal neuralgia irrespective of their age. Radiofrequency coagulation m a y be offered as an alternative for patients with neuralgia in the third division alone. We also offer microvascular decompression to young patients but the majority elect to undergo P M T G after they are told that there is about a 20% chance that their neuralgia will recur within a 5-year period to the extent that they will need a second operation. The four patients with bilatJ. Neurosurg. / Volume 72/April, 1990

Gasserian ganglion microcompression for trigeminal neuralgia eral n e u r a l g i a w h o h a d h a d r f c o a g u l a t i o n or a Frazier o p e r a t i o n o n the c o n t r a l a t e r a l side a n d the m a j o r i t y o f those w h o h a d r e c u r r e n c e after r f c o a g u l a t i o n c l a i m e d t h a t P M T G was m o r e gratifying in t e r m s o f perioperative c o m f o r t a n d f u n c t i o n a l result. L o n g e r follow-up p e r i o d s in series o f patients treated b y P M T G are r e q u i r e d before t h e u l t i m a t e place o f this s i m p l e t e c h n i q u e can be assessed. C o m p a r i s o n o f perm a n e n t sensory loss a n d late r e c u r r e n c e rates in series o f p a t i e n t s t r e a t e d with different degrees o f c o m p r e s s i o n s t a n d a r d i z e d o n a r a d i o g r a p h i c o r pressure measurem e n t basis m a y help to define the m o s t suitable c o m pression m e t h o d . References 1. Abbott KH: Comment on Jaeger R: The results of injecting hot water into the gasserian ganglion for the relief of tic douloureux. J Neurosurg 16:662, 1959 2. Arias M J: Percutaneous retrogasserian glycerol rhizotomy for trigeminal neuralgia. A prospective study of 100 cases. J Neurosurg 65:32-36, 1986 3. Belber C J, Rak RA: Balloon compression rhizolysis in the surgical management of trigeminal neuralgia. Neurosurgery 20:908-913, 1987 4. Brown JA, Preul MC, Modarai B, et al: Percutaneous microcompression for trigeminal neuralgia - - low incidence of severe hypesthesia. J Neurosurg 70:330A, 1989 (Abstract) 5. Burchiel K J, Clarke H, Haglund M, et al: Long-term efficacy of microvascular decompression in trigeminal neuralgia. J Neurosurg 69:35-38, 1988 6. Burchiel KJ, Steege TD, Howe JF, et al: Comparison of percutaneous radiofrequency gangliolysis and microvascular decompression for the surgical management of tic douloureux. Neurosurgery 9:111-119, 1981 7. Christensen JC: Percutaneous gangliolysis of the gasserian ganglion with normal saline as treatment for trigeminal neuralgia. Aeta Neurol Latinoam 3:378-380, 1957 8. Fraioli B, Esposito V, Guidetti B, et al: Treatment of trigeminal neuralgia by thermocoagulation, glycerolization, and percutaneous compression of the gasserian ganglion and/or retrogasserian rootlets: long-term results and therapeutic protocol. Neurosurgery 24:239-245, 1989 9. Graf CJ: Trigeminal compression of tic douloureux. An evaluation. J Neurosurg 20:1029-1032, 1963 10. HSkanson S: Transoval trigeminal cisternography. Surg Neurol 10:137-144, 1978 11. Harris FS, Rhoton AL Jr: Anatomy of the cavernous sinus. A microsurgical study. J Neurosurg 45:169-180, 1976 12. Henderson WR: The anatomy of the gasserian ganglion and the distribution of pain in relation to injections and operations for trigeminal neuralgia. Ann R Coil Surg Engl 37:346-373, 1965 13. Jelasic F: Ober die Behandlung der Trigeminusneuralgie mittels mechanischer Kompression des Ganglion Gasseri durch das Foramen Ovale. Acta Neuroehir 7:440-445, 1959 14. Kehler CH, Brodsky JB, Samuels SI, et al: Blood pressure response during percutaneous rhizotomy for trigeminal neuralgia. Neurosurgery 10:200-202, 1982 15. Latchaw JP Jr, Hardy RW Jr, Forsythe SB, et al: Trigeminal neuralgia treated by radiofrequency coagulation. J Neurosurg 59:479-484, 1983 16. Lunsford LD, Bennett MH: Percutanous retrogasserian glycerol rhizotomy for tic douloureux. Part 1. Technique J. Neurosurg. / Volume 7 2 / A p r i l 1990

and results in 112 patients. Neurosurgery 14:424-430, 1984 17. Mullan S, Lichtor T: Percutanous microcompression of the trigeminal ganglion for trigeminal neuralgia. J Neurosurg 59:1007-1012, 1983 18. Nugent GR: Technique and results of 800 percutaneous radiofrequency thermocoagulation for trigeminal neuralgia. Appl Neurophysiol 45:504-507, 1982 19. Panning B, Sch~iffer J, Kuse WE, et al: Is thermocoagulation of the gasserian ganglion really harmless? Pain Clin 1:179-182, 1987 20. Piatt JH Jr, Wilkins RH: Treatment of tic douloureux and hemifacial spasm by posterior fossa exploration: therapeutic implications of various neurovascular relationships. Neurosurgery 14:462-471, 1984 21. Rish BL: Cerebrovascular accident after percutaneous rf thermocoagulation of the trigeminal ganglion. Case report. J Neurosurg 44:376-377, 1976 22. Sekhar LN, Heros RC, Kerber CW: Carotid-cavernous fistula following percutaneous retrogasserian procedures. Report of two cases. J Neurosurg 51:700-706, 1979 23. Shelden CH, Pudenz RH, Freshwater DB, et at: Compression rather than decompression for trigeminal neuralgia. J Neurosurg 12:123-126, 1955 24. Siegfried J: Percutaneous controlled thermocoagulation of gasserian ganglion in trigeminal neuralgia. Experience with 1000 cases, in Samii M, Jannetta PJ (eds): The Cranial Nerves. New York: Springer-Verlag, 1981, pp 322-330 25. Sondheimer FK: Basal foramina and canals, in Newton TH, Potts DG (eds): Radiology of the Skull and Brain, Vol 1. St Louis: CV Mosby, 1971, pp 287-347 26. Stender A, Grumme T: Late results of gangliolysis as a treatment for trigeminal neuralgia. J Neurosurg 31: 21-24, 1969 27. Sweet WH: The treatment of trigeminal neuralgia (tic douloureux). N Engl J Med 315:174-177, 1986 28. Sweet WH, Poletti CE, Macon JB: Treatment of trigeminal neuralgia and other facial pains by retrogasserian injection of glycerol. Neurosurgery 9:647-653, 1981 29. Sweet WH, Poletti CE, Roberts JT: Dangerous rises in blood pressure upon heating of trigeminal rootlets; increased bleeding times in patients with trigeminal neuralgia. Neurosurgery 17:843-844, 1985 30. Tew JM Jr, Keller JT: The treatment of trigeminal neuralgia by percutaneous radiofrequency technique. Clin Neurosurg 24:557-578, 1977 31. van Loveren H, Tew JM Jr: Comment on Belber C J, Rak RA: Balloon compression rhizolysis in the surgical management of trigeminal neuralgia. Neurosurgery 20: 912-913, 1987 32. van Loveren H, Tew JM Jr, Keller JT, et al: A 10-year experience in the treatment of trigeminal neuralgia. Comparison of percutaneous stereotaxic rhizotomy and posterior fossa exploration. J Neurosurg 57:757-764, 1982 33. Wepsic JG: Complications of percutaneous surgery for pain. Clin Neurosurg 23:454-464, 1976 34. White JC, Sweet WH: Pain and the Neurosurgeon. A Forty-Year Experience. Springfield, II1: Charles C Thomas, 1969, pp 203-204 35. Young RF: Glycerol rhizolysis for treatment of trigeminal neuralgia. J Neurosurg 69:39-45, 1988 Manuscript received June 7, 1989. Accepted in final form September 29, 1989. Address reprint requests to: Ramiro D. Lobato, M.D., Neurosurgery Service, Hospital "1 ~ Octubre," 28041, Madrid, Spain. 553