Neuro-radiology
Neuroradiology(1991) 33:407-410
9 Springer-Verlag1991
Lumbar percutaneous discectomy Initial experience in 28 cases C.Faubert I and W. Caspar2 1 NeuroradiologicalInstituteand 2 Department•fNeur•surgery•University•f•aar•and•H•mburg/•aar,Federa•Repub•ic•fGermany Received: 11 May 1990
Summary. Since november 88, 28 patients with lumbar L5 radiculopathy refractory to conservative care and with a radiologically verified central or mediolateral disc herniation at the level of L4/L5 had had a percutaneous discectomy. Radiological verification consisted of spinal CT + / - myelography, + / - myelo-CT, + / - MRI. A shortterm follow-up analysis of at least 2 months taking the clinical and functional status as well as the professional reintegration into account revealed a 64.3% (18/28patients) satisfactory outcome and a 32.1% (10/28 patients) failure rate. Of the latter 28.6 % (8/28 patients) required further open surgery. One patient whose pain had only partially in regressed was shown at open operation to have a sequestered cranial prolapse as revealed by spinal CT after the percutaneous procedure. There were no major complications. One patient developed a sequestered extraforaminal herniation through the nucleotomy canal three weeks after the procedure. One patient bled for 2 minutes. There were no major vessel injuries. One patient reported local muscular pain, and enhanced nerve root pain after introduction of the trocar sleeve. Key words: Lumbar disc herniation - Percutaneous discectomy
In comparison with standard laminectomy or microdiscectomy procedures [1] lumbar percutaneous discectomy is restricted to about 10 % of patients with disc protrusions [2-5]. It is indicated for contained, moderate (less than 50 % ) medial or mediolateral disc herniations, verified by spinal CT, with or without functional myelography, myeloCT, MRI and on discography, with a corresponding radiculopathy resistant to conservative therapy. The clinical course must be that of a typically evolving sciatica with a predominance of radicular signs over back pain. Absolute contra-indications include paresis, amyotrophy, degenerative instability, rapidly progressing neurological deficits, conus and or cauda equina syndromes. Relative contra-indications include compensation claim patients, facet syndrome, spinal stenosis, spinal deformations. For contained
lumbal disc herniations at the level of L4/L5 some extensor hallucis longus muscle weakness does not exclude the procedure when no amyotrophy is noted. We present shortterm follow-up analysis of 28 patients presenting a L5 radiculopathy refractory to conservative therapy who underwent lumbar discectomy at the level of L4/L5. Patients and methods 28 patients who have undergone percutaneous discectomy at the level of L4/L5 at our center since November 1988 have been followed up for at least 2 months (see Table 1). There were 6 women and 22 men whose ages varied from 25-65 years, (average 42,3 years). Using a posterolateral approach [6] homolateral to the predominant sciatica, under local anesthesia, the middle of the L4/L5 intervertebral disc space was reached (controlled by bi-plane fluoroscopy) using cannulae, guide wire and working sleeve sequentially (Aesculap instruments: external diameter 5.4 ram, internal diameter 4.6 ram). Using nucleus forceps, hand extirpation allowed much soft disc to be removed. The rest was extirpated using different motor driven frontal cutting instruments (cutters and resectors) linked to an irrigating and high-vaccuum suction system. The aspiration was stopped when no more material was obtained (usually after 20 min). The radiological work-up included X-rays of the lumbar spine and spinal CT scans, with or without myelography, myelo-CT, and/or MRI. No pre- or peroperative discography was performed. All patients were later clinically controlled on an outpatient basis. Average stay at the hospital was 2 days. According the clinical, functional and professionalcriterias. The outcome for the patients was classified in 3 groups. Group (1) Good. Patient fully returned to previous or similar work, mild remaining but significantly diminished leg pain and/or back pain. Group (2) Fair. Leg pain relief, improved functional status, but patient had to change occupation.
408 Table L Summary of clinical manifestations and outcome Pa- Age tient
Sex *
Results
Clinical condition
Follow-up /outcome
Evaluation
Op.L4/5x3yr. now 8 > L. left
op. 3 months after 3 op. 3 months after 3
1
43F
F
2
43
F
Lleft x 3 months
3
50
F
L left x 1 yr.
17 months
4
56
M
L right x 4 yr.
op. 3 months after 3
1
5
27
M
Lleft x 8 months
14 months
2
6
48
F
L right x 3 months 14 months
1
7
63
M
L left x yrs
post-op. CT sequester L4/5. op. 2 weeks later
3
8
49
M
L right x 9 yrs
1 yr.
1
9
39
M
L left x 6 months
i yr.
1
10
46
F
L right x yrs.
op. 3 months later 3
11
29
M
L right x 1yr.
8 months
12
31
M
L left x 6 months
7 months
1
13
46
M
L right x 5 yrs.
7 months
1
1
A s u m m a r y of the clinical m a n i f e s t a t i o n s a n d o u t c o m e is s h o w n on T a b l e 1.15/28 p a t i e n t s (53.6 % ) b e l o n g e d to t h e first g r o u p , 3/28 p a t i e n t s (10.7 % ) to t h e s e c o n d a n d 10/28 (35.7 % ) to t h e t h i r d g r o u p . A s in the l i t e r a t u r e t h e first t w o g r o u p s can b e c o n s i d e r e d sucessful. A s h o r t - t e r m success r a t e o f 64.3 % (18/28 p a t i e n t s ) is a c h i e v e d versus a 35.7 % (10/28 p a t i e n t s ) failure rate. 9/28 p a t i e n t s r e q u i r e d f u r t h e r o p e n surgery. 4 p a t i e n t s (cases 1, 18, 20, 21) w e r e p o o r i n d i c a t i o n s b e c a u s e o f spinal stenosis, l a t e r a l i z e d fora m i n a l h e r n i a t i o n s , p r e d o m i n a n c e of b a c k p a i n o v e r leg pain, a n d all w e r e failures. T h e y w e r e t a k e n in a c o n t e x t of p a t i e n t a n d m e d i c a l insistence. If t h e p a t i e n t s ' clinical status r e m a i n e d u n c h a n g e d o r w o r s e n e d , w e d i d n o t syst e m a t i c a l l y w a i t six w e e k s to p r o p o s e s u r g e r y as o t h e r a u t h o r s suggest. T h e r e w e r e n o m a j o r o p e r a t i v e c o m p l i c a tions (see T a b l e 3). T h e only two m i n o r c o m p l i c a t i o n s inv o l v e d o n e p a t i e n t (case 28) w h o e x p e r i e n c e d a c u t e leg p a i n (which i m m e d i a t e l y r e g r e s s e d ) a f t e r i n t r o d u c t i o n of t h e t r o c a r sleeve. S u b s e q u e n t s u r g e r y i w e e k l a t e r rev e a l e d an i n f l a m m e d L5 n e r v e r o o t . T h e o t h e r (case 22) h a d a s h o r t e p i s o d e of b l e e d i n g for t w o minutes. P o s t o p e r ative c o u r s e was uneventfull. O n e p a t i e n t (case 23) initially i m p r o v e d a n d t h e n 3 w e e k s l a t e r as he c l i m b e d i n t o his car d e v e l o p e d an e x t r a f o r a m i n a l p r o l a p s e t h r o u g h t h e n u c l e o t o m y c a n a l (see Fig. 5). D i s c o g r a p h y was n o t p e r f o r m e d . O n e p a t i e n t (case 7), c a m e w i t h spinal C T scans consisting o f 4 m m t h i c k slices. H e d i d n o t r e s p o n d well a n d a p o s t o p e r a t i v e spinal C T with thin slices s h o w e d a seq u e s t e r e d c r a n i a l p r o l a p s e c o n f i r m e d b y o p e n surgery: T h e r e was n o c o r r e l a t i o n b e t w e e n t h e a m o u n t of soft disc
14
25
M
L left x 4 months
7 months
2
15
57
M
L left + right x 10 yrs.
6 months
2
16
27
M
L + $1 right x 2yrs.
6 months
1
17
38
M
L right x 6 months 6 months
1
18
44
M *
3
19
44
M
E > L r i g h t E M G : 5 months normal 8++ 4 months L right x yrs
20
31
M *
Lrightx6weeks op. 2 weeks after lateralized herniation
3
L right > left spinal stenosis
op. 2 weeks after
3
Age
Total
S
F
Open surgery
3 months
1
20-29 30-39 40-49 50-59 60q59
5 6 9 6 2
4 (80 %) 5 (83 %) 5 (55.6 %) 4 (66.7 %) 0 (0 %)
1 1 4 2 2
1 1 3 2 2
Total
28
18(64.3%)
10(35.7%)
9
*
1
Table 2. Outcome of patients as a function of age
21
65
F
22
53
M
L left x 2 months
23
51
M
3 L right x 6 months complete pain regression for 3 weeks then extraforaminal sequester through nucleotomy canal which was operated upon
S, success; F, failure
24
41
M
L left x 2 yrs.
21/2months
1
Table 3. Summary of complications
25
30
M
L left x 6 months
2 months
1
Operative
26
51
M
L left x 6 weeks
2 months
1
Syncopal episode
0
Discitis
0
1
Vascular injury
0
Post-procedure back spasm
0
Nerve root or dura injury
0
Other
1
Retroperitoneal injury
0
27 28
31 26
M M
L left right x 2 yrs. 2 months L right x 11/2yrs. op. i week later
3
F, female; M, male; L, leg pain, radiculopathy L5; B, back pain; Groups: 1 = good, 2 = fair, 3 = failure;, = wrong indication All patients had back and leg pain.
G r o u p (3) F a i l u r e . N o leg o r b a c k p a i n relief, o r w o r s e n i n g o f c o n d i tion, u n a b l e to r e s u m e w o r k o r o t h e r activities. T h e first two g r o u p s a r e c o n s i d e r e d sucessful.
Postoperative
- Other minor complications 2 - (case # 28): acute leg pain after introduction of the trocar sleeve. Open surgery revealed an inflammed L5 nerve root. - (case # 22): After annular fibrosus trepanation, short bleeding for 2 minutes.
- (case # 23): developed an extraforaminal disc herniation through the nucleotomy canal 3 weeks after.
409
Fig. 1. Typical appearance of extracted soft disc Fig.2. Case # 28. Medial protrusion L4/L5. Pre- (a) and postoperative (b) Ct scans (4 weeks after). Notice the nucleotomy canal on the right (arrowheads). The protrusion is unchanged (typical)
Table 2 shows that patients u n d e r the age of 40 generally r e s p o n d better. This is due to the higher incidence of d e g e n e r a t i v e spine with increasing age.
Discussion material aspirated (see Fig. 1) and leg pain regression. S o m e patients had disc space n a r r o w i n g following percutaneous discectomy (see Fig. 4).
O u r s h o r t - t e r m 64.3 % success rate indicates that percutaneous discectomy in e x p e r i e n c e d hands and w h e n restricted to the p r o p e r patient p o p u l a t i o n is a viable aterna-
Fig.3. Sagittal MR scan. (1 Tesla/TR 1,8 s/TE 90 ms). T2-weighted images 3 months after percutaneous discectomy. The nucleotomy canal is hypointense (arrowheads). Dehydration of discs L4/L5, L5/S 1 Ng.4. Ire- (a) and postoperative (b) (4 weeks) proton density weighted images. Sagittal MR scans. Notice the significant IA/L5 disc space reduction. Case # 24 Fig.5. Pre- (a) and postoperative (b) L4/L5 CT scans. Notice the large ((b) arrowheads), surgically-verified extraforaminal prolapse through the nucleotomy canal 3 weeks after a percutaneous nucleotomy. Case # 23
410 tive to open surgery as a first step procedure. The absence of scarring, short-hospital stay and early return to full activity are obvious advantageous. Our short-term results compare favourably with teams using the a u t o m a t e d percutaneous discectomy (so called "Nucleotome"). The latter report for 3031 cases success rates ranging from 61% ( G e r m a n y ) to 87 % (Netherlands) for an overall 77 % success rate [7]. The ]0rocedure does not influence the results of eventual subsequent open surgery. The relatively large size of the instrument allows rapid soft tissue extirpation. It can only be used at the level of L4/L5 and above. The relatively large working sleeve was responsible for a nerve root irritation (case 28) and for an extraforaminal prolapse through the nucleotomy canal (case 23). As far as we know the latter has never been reported before. Just how much material should be aspirated is unclear. M o r e material aspiration would probably give a lower recurrence rate but m a y lead to disc space narrowing with eventual consecutive segmental instability with development of facet joint h y p e r t r o p h y and mechanical back pain in the long term. Further follow-up studies are necessary. A thorough multimodal radiological work-up is necessary. L u m b a r X-rays and spinal CT scans are compulsary. Sagittal M R I scans [8] do not replace CT but show the sequesters and the functional state of the disc. Functional myelography m a y still have its place and can be completed with a myelo-CT. If a doubt still exists as to whether the ligamentum longitudinale posteriore is perforated, a peroperative discography m a y be performed. In the later case it would show contrast diffusion in the epidural space in which case the procedure would
be contraindicated. Discography increases the infection risk.
Acknowledgements. We would like to thank our photographer Mr. Czech and secretary Mrs. Schrnidt for their excellent technical assistance.
References 1. Caspar W, Iwa H (1979) A microsurgical operation for lumbar disc herniations. Neurological surgery 6:657-662 2. Caspar W (1988) The microsurgical technique for herniated lumbar disc operations, 4th ed. Aesculap AG Scientific information, Tuttlingen, pp 6-7 3. Hijikata S, Jamagishim, Nakayama T, Oormosik (1975) Percutaneous discectomy: a new treatment method for lumbar disc herniation. J Toden Hosp 5:5-13 4. Suezawa Y, Jacob AC (1986) Percutaneous nucleotomy, an alternative to spinal surgery. Arch Orthop Trauma Surg 105:287-295 5. Maroon JC, Onik G (1987) Percutaneous automated discectomy: a new method for lumbar disc removal. J Neurosurg 66:143-146 6. Kanter SL, Friedmann WA (1985) Percutaneous discectomy: an anatomical study. Neurosurgery 16:141-147 7. Onik G (1989) Summation of APLD clinical experience. International symposium on the state of art of percutaneous Iumbar discectomy, May 25-26, Marbella, Spain (Paper 38) 8. Schneiderman G, Flannigon B, Kingston S, Thomas J, Dillin WH, Watkins RG (1987) Magnetic resonance imaging in the diagnosis of disc degeneration: correlation with discography. Spine 12: 275-281 C. Faubert, M. D. Neuroradiological Institute University of Saarland W-6650 Homburg/Saar Federal Republic of Germany
Neuroradiology(1991) 33:407-410
9 Springer-Verlag1991
Lumbar percutaneous discectomy Initial experience in 28 cases C.Faubert I and W. Caspar2 1 NeuroradiologicalInstituteand 2 Department•fNeur•surgery•University•f•aar•and•H•mburg/•aar,Federa•Repub•ic•fGermany Received: 11 May 1990
Summary. Since november 88, 28 patients with lumbar L5 radiculopathy refractory to conservative care and with a radiologically verified central or mediolateral disc herniation at the level of L4/L5 had had a percutaneous discectomy. Radiological verification consisted of spinal CT + / - myelography, + / - myelo-CT, + / - MRI. A shortterm follow-up analysis of at least 2 months taking the clinical and functional status as well as the professional reintegration into account revealed a 64.3% (18/28patients) satisfactory outcome and a 32.1% (10/28 patients) failure rate. Of the latter 28.6 % (8/28 patients) required further open surgery. One patient whose pain had only partially in regressed was shown at open operation to have a sequestered cranial prolapse as revealed by spinal CT after the percutaneous procedure. There were no major complications. One patient developed a sequestered extraforaminal herniation through the nucleotomy canal three weeks after the procedure. One patient bled for 2 minutes. There were no major vessel injuries. One patient reported local muscular pain, and enhanced nerve root pain after introduction of the trocar sleeve. Key words: Lumbar disc herniation - Percutaneous discectomy
In comparison with standard laminectomy or microdiscectomy procedures [1] lumbar percutaneous discectomy is restricted to about 10 % of patients with disc protrusions [2-5]. It is indicated for contained, moderate (less than 50 % ) medial or mediolateral disc herniations, verified by spinal CT, with or without functional myelography, myeloCT, MRI and on discography, with a corresponding radiculopathy resistant to conservative therapy. The clinical course must be that of a typically evolving sciatica with a predominance of radicular signs over back pain. Absolute contra-indications include paresis, amyotrophy, degenerative instability, rapidly progressing neurological deficits, conus and or cauda equina syndromes. Relative contra-indications include compensation claim patients, facet syndrome, spinal stenosis, spinal deformations. For contained
lumbal disc herniations at the level of L4/L5 some extensor hallucis longus muscle weakness does not exclude the procedure when no amyotrophy is noted. We present shortterm follow-up analysis of 28 patients presenting a L5 radiculopathy refractory to conservative therapy who underwent lumbar discectomy at the level of L4/L5. Patients and methods 28 patients who have undergone percutaneous discectomy at the level of L4/L5 at our center since November 1988 have been followed up for at least 2 months (see Table 1). There were 6 women and 22 men whose ages varied from 25-65 years, (average 42,3 years). Using a posterolateral approach [6] homolateral to the predominant sciatica, under local anesthesia, the middle of the L4/L5 intervertebral disc space was reached (controlled by bi-plane fluoroscopy) using cannulae, guide wire and working sleeve sequentially (Aesculap instruments: external diameter 5.4 ram, internal diameter 4.6 ram). Using nucleus forceps, hand extirpation allowed much soft disc to be removed. The rest was extirpated using different motor driven frontal cutting instruments (cutters and resectors) linked to an irrigating and high-vaccuum suction system. The aspiration was stopped when no more material was obtained (usually after 20 min). The radiological work-up included X-rays of the lumbar spine and spinal CT scans, with or without myelography, myelo-CT, and/or MRI. No pre- or peroperative discography was performed. All patients were later clinically controlled on an outpatient basis. Average stay at the hospital was 2 days. According the clinical, functional and professionalcriterias. The outcome for the patients was classified in 3 groups. Group (1) Good. Patient fully returned to previous or similar work, mild remaining but significantly diminished leg pain and/or back pain. Group (2) Fair. Leg pain relief, improved functional status, but patient had to change occupation.
408 Table L Summary of clinical manifestations and outcome Pa- Age tient
Sex *
Results
Clinical condition
Follow-up /outcome
Evaluation
Op.L4/5x3yr. now 8 > L. left
op. 3 months after 3 op. 3 months after 3
1
43F
F
2
43
F
Lleft x 3 months
3
50
F
L left x 1 yr.
17 months
4
56
M
L right x 4 yr.
op. 3 months after 3
1
5
27
M
Lleft x 8 months
14 months
2
6
48
F
L right x 3 months 14 months
1
7
63
M
L left x yrs
post-op. CT sequester L4/5. op. 2 weeks later
3
8
49
M
L right x 9 yrs
1 yr.
1
9
39
M
L left x 6 months
i yr.
1
10
46
F
L right x yrs.
op. 3 months later 3
11
29
M
L right x 1yr.
8 months
12
31
M
L left x 6 months
7 months
1
13
46
M
L right x 5 yrs.
7 months
1
1
A s u m m a r y of the clinical m a n i f e s t a t i o n s a n d o u t c o m e is s h o w n on T a b l e 1.15/28 p a t i e n t s (53.6 % ) b e l o n g e d to t h e first g r o u p , 3/28 p a t i e n t s (10.7 % ) to t h e s e c o n d a n d 10/28 (35.7 % ) to t h e t h i r d g r o u p . A s in the l i t e r a t u r e t h e first t w o g r o u p s can b e c o n s i d e r e d sucessful. A s h o r t - t e r m success r a t e o f 64.3 % (18/28 p a t i e n t s ) is a c h i e v e d versus a 35.7 % (10/28 p a t i e n t s ) failure rate. 9/28 p a t i e n t s r e q u i r e d f u r t h e r o p e n surgery. 4 p a t i e n t s (cases 1, 18, 20, 21) w e r e p o o r i n d i c a t i o n s b e c a u s e o f spinal stenosis, l a t e r a l i z e d fora m i n a l h e r n i a t i o n s , p r e d o m i n a n c e of b a c k p a i n o v e r leg pain, a n d all w e r e failures. T h e y w e r e t a k e n in a c o n t e x t of p a t i e n t a n d m e d i c a l insistence. If t h e p a t i e n t s ' clinical status r e m a i n e d u n c h a n g e d o r w o r s e n e d , w e d i d n o t syst e m a t i c a l l y w a i t six w e e k s to p r o p o s e s u r g e r y as o t h e r a u t h o r s suggest. T h e r e w e r e n o m a j o r o p e r a t i v e c o m p l i c a tions (see T a b l e 3). T h e only two m i n o r c o m p l i c a t i o n s inv o l v e d o n e p a t i e n t (case 28) w h o e x p e r i e n c e d a c u t e leg p a i n (which i m m e d i a t e l y r e g r e s s e d ) a f t e r i n t r o d u c t i o n of t h e t r o c a r sleeve. S u b s e q u e n t s u r g e r y i w e e k l a t e r rev e a l e d an i n f l a m m e d L5 n e r v e r o o t . T h e o t h e r (case 22) h a d a s h o r t e p i s o d e of b l e e d i n g for t w o minutes. P o s t o p e r ative c o u r s e was uneventfull. O n e p a t i e n t (case 23) initially i m p r o v e d a n d t h e n 3 w e e k s l a t e r as he c l i m b e d i n t o his car d e v e l o p e d an e x t r a f o r a m i n a l p r o l a p s e t h r o u g h t h e n u c l e o t o m y c a n a l (see Fig. 5). D i s c o g r a p h y was n o t p e r f o r m e d . O n e p a t i e n t (case 7), c a m e w i t h spinal C T scans consisting o f 4 m m t h i c k slices. H e d i d n o t r e s p o n d well a n d a p o s t o p e r a t i v e spinal C T with thin slices s h o w e d a seq u e s t e r e d c r a n i a l p r o l a p s e c o n f i r m e d b y o p e n surgery: T h e r e was n o c o r r e l a t i o n b e t w e e n t h e a m o u n t of soft disc
14
25
M
L left x 4 months
7 months
2
15
57
M
L left + right x 10 yrs.
6 months
2
16
27
M
L + $1 right x 2yrs.
6 months
1
17
38
M
L right x 6 months 6 months
1
18
44
M *
3
19
44
M
E > L r i g h t E M G : 5 months normal 8++ 4 months L right x yrs
20
31
M *
Lrightx6weeks op. 2 weeks after lateralized herniation
3
L right > left spinal stenosis
op. 2 weeks after
3
Age
Total
S
F
Open surgery
3 months
1
20-29 30-39 40-49 50-59 60q59
5 6 9 6 2
4 (80 %) 5 (83 %) 5 (55.6 %) 4 (66.7 %) 0 (0 %)
1 1 4 2 2
1 1 3 2 2
Total
28
18(64.3%)
10(35.7%)
9
*
1
Table 2. Outcome of patients as a function of age
21
65
F
22
53
M
L left x 2 months
23
51
M
3 L right x 6 months complete pain regression for 3 weeks then extraforaminal sequester through nucleotomy canal which was operated upon
S, success; F, failure
24
41
M
L left x 2 yrs.
21/2months
1
Table 3. Summary of complications
25
30
M
L left x 6 months
2 months
1
Operative
26
51
M
L left x 6 weeks
2 months
1
Syncopal episode
0
Discitis
0
1
Vascular injury
0
Post-procedure back spasm
0
Nerve root or dura injury
0
Other
1
Retroperitoneal injury
0
27 28
31 26
M M
L left right x 2 yrs. 2 months L right x 11/2yrs. op. i week later
3
F, female; M, male; L, leg pain, radiculopathy L5; B, back pain; Groups: 1 = good, 2 = fair, 3 = failure;, = wrong indication All patients had back and leg pain.
G r o u p (3) F a i l u r e . N o leg o r b a c k p a i n relief, o r w o r s e n i n g o f c o n d i tion, u n a b l e to r e s u m e w o r k o r o t h e r activities. T h e first two g r o u p s a r e c o n s i d e r e d sucessful.
Postoperative
- Other minor complications 2 - (case # 28): acute leg pain after introduction of the trocar sleeve. Open surgery revealed an inflammed L5 nerve root. - (case # 22): After annular fibrosus trepanation, short bleeding for 2 minutes.
- (case # 23): developed an extraforaminal disc herniation through the nucleotomy canal 3 weeks after.
409
Fig. 1. Typical appearance of extracted soft disc Fig.2. Case # 28. Medial protrusion L4/L5. Pre- (a) and postoperative (b) Ct scans (4 weeks after). Notice the nucleotomy canal on the right (arrowheads). The protrusion is unchanged (typical)
Table 2 shows that patients u n d e r the age of 40 generally r e s p o n d better. This is due to the higher incidence of d e g e n e r a t i v e spine with increasing age.
Discussion material aspirated (see Fig. 1) and leg pain regression. S o m e patients had disc space n a r r o w i n g following percutaneous discectomy (see Fig. 4).
O u r s h o r t - t e r m 64.3 % success rate indicates that percutaneous discectomy in e x p e r i e n c e d hands and w h e n restricted to the p r o p e r patient p o p u l a t i o n is a viable aterna-
Fig.3. Sagittal MR scan. (1 Tesla/TR 1,8 s/TE 90 ms). T2-weighted images 3 months after percutaneous discectomy. The nucleotomy canal is hypointense (arrowheads). Dehydration of discs L4/L5, L5/S 1 Ng.4. Ire- (a) and postoperative (b) (4 weeks) proton density weighted images. Sagittal MR scans. Notice the significant IA/L5 disc space reduction. Case # 24 Fig.5. Pre- (a) and postoperative (b) L4/L5 CT scans. Notice the large ((b) arrowheads), surgically-verified extraforaminal prolapse through the nucleotomy canal 3 weeks after a percutaneous nucleotomy. Case # 23
410 tive to open surgery as a first step procedure. The absence of scarring, short-hospital stay and early return to full activity are obvious advantageous. Our short-term results compare favourably with teams using the a u t o m a t e d percutaneous discectomy (so called "Nucleotome"). The latter report for 3031 cases success rates ranging from 61% ( G e r m a n y ) to 87 % (Netherlands) for an overall 77 % success rate [7]. The ]0rocedure does not influence the results of eventual subsequent open surgery. The relatively large size of the instrument allows rapid soft tissue extirpation. It can only be used at the level of L4/L5 and above. The relatively large working sleeve was responsible for a nerve root irritation (case 28) and for an extraforaminal prolapse through the nucleotomy canal (case 23). As far as we know the latter has never been reported before. Just how much material should be aspirated is unclear. M o r e material aspiration would probably give a lower recurrence rate but m a y lead to disc space narrowing with eventual consecutive segmental instability with development of facet joint h y p e r t r o p h y and mechanical back pain in the long term. Further follow-up studies are necessary. A thorough multimodal radiological work-up is necessary. L u m b a r X-rays and spinal CT scans are compulsary. Sagittal M R I scans [8] do not replace CT but show the sequesters and the functional state of the disc. Functional myelography m a y still have its place and can be completed with a myelo-CT. If a doubt still exists as to whether the ligamentum longitudinale posteriore is perforated, a peroperative discography m a y be performed. In the later case it would show contrast diffusion in the epidural space in which case the procedure would
be contraindicated. Discography increases the infection risk.
Acknowledgements. We would like to thank our photographer Mr. Czech and secretary Mrs. Schrnidt for their excellent technical assistance.
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