Tumors of the cauda equina: the importance of an early diagnosis

Tumors of the cauda equina: the importance of an early diagnosis Roelfien

I. HogenEsch*

and Michiel J. Staal*

Introduction Summary

Tumors of the cauda equina are uncommon, representing about 1% of the central nervous system tumors’. They can lead to severe disability. The reversibility of associated neurological dysfunction is strongly related to the interval between the time of onset of symptoms and the time of treatmenP4. Therefore early diagnosis is of paramount importance. However, the symptomatology often lacks characteristic features, since it can mimic other more common sciatic syndromes. In this paper the clinical course, the examination and the results of treatment in 13 patients presenting with a cauda equina tumor, are analysed and discussed. Patients and methods

Key words: Cauda equina tumor, neurolo~~l dysfunction, histology, prognosis

Thirteen patients with a cauda equina tumor (Table 1) were retrospectively studied. They have all been operated in the period 1980-1985 in the University Hospital in Groningen after being referred from a neurological clinic. Referral took place after the clinical diagnosis was established. The pre-operative clinical patient data were extracted from the medical records of the referring neurologists and from the neurosurgical admission files. Ten of the 13 patients were postoperatively interviewed and neurologically examined by both authors. Three patients were lost to follow-up, one of them becau-

* Department of Neurosurgery,

The natural history of cauda equina tumors was studied in 13 patients. Pain was the most prominent clinical manifestation. Neurological dysfunction mainly consisted of sensory disturbances. The pre-operative course was in 62% three years or longer. A relation was found between the histology of the tumor and the delay of diagnosis: ependymomas were discovered much later than schwannomas. Other histological types of tumors were meningioma, sarcoma and metastasis of a meduliobiastoma. The effect of treatment, in nine cases only surgical, was excellent in seven of the 13 patients. The prognosis was determined by histology and length of pre-operative period.

University Hospital Groningen,

se of death. The interval between operation and follow-up varied between three months and 4.5 years (mean: 1.9 years). Six of the 13 patients were female and seven male. The age at the time of operation ranged from 14 to 60 years (mean: 40 years). The average duration of the pre-operative morbidity was almost six years (range: one month - 25 years). One patient (nr. 11) was operated on for a cauda equina tumor elsewhere five years before.

P. 0. Box 30.001,

9700RB Groningen, The Netherlands.

Address for correspondence and reprint requests: M.J. Staal, Department of Neurosurgery, Box 30.001, 9700 RB Groningen, The Netherlands.

University Hospital Groningen,

P. 0.

Accepted 16.6.88 Clin Neural Neurosurg

1988. Vol W-4

343

Table 1. Clinical data of 13 patients treated for a cauda equina tumor Patient (age a* time of treatment)

Duration of complaints

Removal

Pathological diagnosis

Radiotherapy (dose. Gy)

(years)

Inuwl treatmentfollow-up

Results of treatment

Remark\ ____--

pain

@WSl

motor disturhances

sensory disturhances

micturitio” and sexual function

l.F.50 2. F. 34

3

complete

3.3

benign

1’

1

0

1

schwannoma benign

0.25

I

0

I

recurrence preopefatwe

complaints

schwa”“oma 3, F. 51 4, M, 35

6 3.5

COlllpkte

benign

09

2

3

1

complete

schwannoma beni@

I.7

2

0

I

xbwannoma 5.M,36

1

complete

benign xhwannoma

2

1

0

0

6. F, 37

0.6

complete

be”@ schwannoma

2.25

1

0

0

I. F. 15

1.25

complete

benign xhwannoma

1 25

1

0

1

4.5

?

7

1.25

7

?

8.M.60

1s

incomplete

bet@ ependymoma

9.M,34

13

complete

benip

50 local

?

stamp,

?

?

ll.M.60

25 0.2

incomplete complete

benign ependymoma meningioma

rduscd cooparatio”, preop: pain and sensory diirbances

ependymoma 10. F. SE

refused cooperation, preop: pain, motor, sensory, sfittctez and sexual $wpilwema

50 locs1

1.1

1

3

3

3

3.1

1

0

1

0

2

4

3

3

?

7

?

?

38 cmniosp. was operated on S years before

(low grade 12, M. 41 13. M, 14

3 0.1

incomplete i”complcte

malign) sarconla mettwtasis medul-

6Olocal

0.6

10 toeal

_

died of muifiple brain metastasis 6 week post-oparatively

4.5 craniosp.

loblastoma

Legend:

F = female. M = male 0 = “or present before, neither after operation 1 = improved

Symptms and signs The main symptoms are shown in Table 2. The initial and most prominent symptom was pain. In 11 patients the pain was intermittently sustaining and slowly worsening at first, becoming continuous in the end, whereas in two patients the pain was continuously progressing from onset. At first the pain was localized at the lower back and/or irradiating into the legs. Sciatic pain was mostly unilateral at the time of onset and was increased by coughing, sneezing and straining in ten patients. In eight the pain worsened at night by lying down and was relieved by walking around or kneeling down. Ten patients received analgesics or physiotherapy, in all of them without relief. Three patients suffered from coldness in one or both legs. Sphincter disturbances were accounted in five patients of whom two also compl~ned of sexual dysfunction. Neurological examination (Table 3) showed limited mobility of the lumbar spine in at least seven patients at the time of admission. Initially 344

2 = no further deterioration 3 = worsened

4 = only present after operation ‘) = unknown

motor and sensory disturbances were infrequently present. However, at the time of diagnosis, neurological dysfunction was seen in all patients. Decreased sensation involving mostly more than one dermatome was present. Especially the lower lumbar and upper sacral segments were affected. In four patients motor disturbances were present: two of them showing only a slight paresis of the lower extremities and in two of them a foot drop had developed. One patient (nr. 10) had recurrent periods of a foot drop during nine years before her tumor was recognized. In one patient papihedema resulting in vision disturbances finally lead to the diagnosis of a cauda equina tumor, after sustaining low back pain for 15 years. Additional investigations Although radiological examination was performed in different hospitals, the final radiolo~~l diagnosis was confirmed after reviewing the material by neuroradiologists of the Department of Neuroradiology of the University Hospital in Groningen. Plain X-ray of the lumbar spine sho-

Table 2. Symptoms at time of onset and at time of examination

TabIe 3. Signs at time of examination 5gn.r

Symptoms

Low back pain Sciatica Low back pain with sciatica Paresthesia Hypesthesia Motor disturbances Coldness of legs Sphincter disturbances

Number of patients onset exammation 3 1

6 4 2 0 1 1 0

3 9 3 10 4 3 5

wed abnormalities in ten patients (Table 4). Congenital defects were present in five patients (38%), consisting of discontinuity of the neural arch and sacralization of the lower lumbar segment. Usuration of the bony structures of the lumbosacral spine was seen in four patients. Myelography was performed in all patients, once by a cervical and in the other patients by a lumbar puncture. It showed a subtotal (five patients) or a complete block (eight patients) of the water soluble contrast fluid, in six patients occurring at the L4-L5 level. Additional computerized tomography of the lumbar spine was done in five patients. In case of a total block the complementary information was given by visualization of the counter pole of the tumor. It showed the abnormal content of the spinal canal in all five cases. The results of the laboratory examination of the cerebrospinal fluid (CSF) obtained during myelography revealed elevated protein levels in 12 patients, ranging from 0.55 to 17.0 gr/l (Table 5). In only one patient, who had a cervical puncture, the total protein content of the CSF was normal (0.42 gr/l). Therapy and histological diagnosis

All patients underwent surgery performed by different qualified neurosurgeons. The operation consisted of one or more laminectomies followed by intraspinal exploration. The tumors, all situated intradurally, could be completely removed in nine cases. In the other four cases too much adherence of the tumor of the cauda equina roots made total extirpation without sacrificing neural tissue impossible. These tumors were removed subtotally and operation

Number

Remarks

of

patients

Limited motion of lumbar spine Sensory disturbances Motor disturbances Difference in skin temperature of the legs Absent or diminished ankle jerk Positive straight leg raising test Papilledema

7 11 4

5 not known 4 bilateral 1 bilateral

3 5 5 1

3 not known

was followed by radiation therapy in these cases. The results of pathological examination are shown in Table 1. There was a preponderance of benign schwannomas, which all of them could be extirpated completely. Results The results of treatment are shown in Table 1. In all seven patients with a benign schwannoma, pain was present before operation and disappeared completely in five of them afterwards. However, in one of them (nr. 1) recurrence of pain two years after operation made reinvestigation necessary and re-exploration was needed revealing regrowth of the schwannoma at the same site. Six of the patients lacked motor disturbances pre- and postoperatively. In patient nr. 3 slight paresis of the upper leg muscles had postoperatively extended to the muscles innervated by the L5 root. In this patient bladder function was disturbed shortly after operation but restored completely within a few weeks. Patient nr. 7, with a schwannoma of the LS-Sl root, had acute complete urinary retention preoperatively and showed only slight retention one year afterwards. Two of the three patients with an ependymoma refused cooperation in the follow-up. In the third patient who suffered from low back pain during 25 years and who had severe motor and sensory disturbances during nine years, the pain disappeared gradually after treatment, but the neurological dysfunction increased in severity and had extended. Furthermore severe micturition problems worsened and defaecation pro345

Table 4. Plain X-ray findings

Table 5. Total protein in liquor @/I) -

Findings

Number

Scoliosis Congenital defects Erosion of pedicles Erosion of Iaminae Scalloping Widening of lumbar spinal canal

?

of putients 6 5 3 3 2 I

1

blems developed immediately after operation. They improved slightly afterwards. In the patient with the meningioma all preoperative signs and symptoms disappeared completely after operation. Patient nr. 12 (sarcoma) suffered from violent lower back and unilateral sciatic pain and had bilateral hypesthesia in the lower sacral dermatomes. Micturition and sexual function were severely disturbed pre-operatively. After operation sensory, micturition and sexual functions had deterioated. In addition slight paresis of the lower leg and defaecation disturbances had developed. The patient with a metastasis of a medulloblastoma had been operated on for his primary tumor two years before. At the operation of his low back only a large decompression could be achieved. Pre-operative complaints had not improved post-operatively except the pain. During radiotherapy signs of intracranial recurrence developed. Continuation of treatment was refused by the patient. Discussion In this paper the clinical course and the results of treatment of 13 patients with a cauda equina tumor are presented. A remarkable feature of the clinical course is the longst~ding pre-operative history, in our series a mean time of almost six years. No correlation could be found between the histological diagnosis and the length of pre-operative history, with an exception for ependymomas, only being diagnosed after 13 years. This is in accordance with the results of Feamside and AdamG. It is often diicult to establish the moment of onset of the history, especially when pain is the only initial symptom. This can be-an explanation for the variability of the diagnostic delay in the 346

Totalprotein

Number

ofputuwc

< 0,45 1),45 - 1,cKl

1 1

1,oo- 2.00

4 7

s2,oo

J

different published series: Van Duinenh for instance found two years, and Love’ 6.3 years. However, in all published series the histories are long2,5,W’0, which is probably due to the late onset of neurological signs and the aspecific symptomatolo~ of cauda equina tumors. The most common presenting symptom among our patients was pain, -usually low back pain with or without sciatica. This pain was also found by others2’7@‘2, although painless tumors of the cauda equina are described’. The pain is mostly intermittent in the early phase3*5*7,10J1, and progressive in a later stage, as was seen in 11 of our patients. Eight of our 13 patients experienced nocturnal pain and relief in upright position. Pam in recumbency was ako noted by other authorsz‘~,~~,ll. It can be a useful feature in the differential diagnosis with a lumbar disc herniation. Impassiveness of pain to conservative treatment is another differential characteristic2*1’. Rarely a cauda equina tumor presents with acute pain due to subarachnoidal bleeding2*sa’3. In a later stage neurological disturbances occur. In our patients sensory dysfunction (paresthesia, hypesthesia) was seen more frequently than paresis. This domination was not described in other papers, where sensory and motor disturbances were found to occur almost equally2-4.6.11, or where motor disturbances dominateds. The extent of the neurological dist~bances vary from one to several segments. Trophic changes due to loss of autonomic supply including edema, coldness and ulcers, can occur in cauda equina tumorslo. Three of our patients suffered from coldness in the legs. In general a fixed pattern of development of sensory, motor or trophic d~sturb~ces was nor observed in our patients, neither described in literature. Sphincter dysfunction is mostly considered as a late complication2-J~6~11, although early occurrence has been noticed2J2, In our group sphinc-

ter disturbances were encountered briefly before operation in five patients. Two patients showed sexual dysfunction. One of our patients developed papilledema, which is a rare finding in cauda equina tumors. The genesis of papilledema in association with a cauda equina tumor is not exactly known. Some authors assume a disturbance in the CSF resorption as a result of high protein levels5~‘2*‘4*‘5. In six of our 13 patients initially a lumbar disc herniation was erroneously diagnosed. Indeed this syndrome can mimic the symptoms and signs of a cauda equina tumor. However, there are several differential criteria. The pattern of pain as described above, is one of them. Another criterion is the usually less extensive and unilateral neurological dysfunction in lumbar disc herniation. Protein contents above lgr/l, found in 11 of our 13 patients, seems to speak in favour of a cauda equina tumor2.4,5, although the CSF protein level can also be elevated in lumbar disc herniation. Other causes of the low back syndrome which can pose a problem in the differential diagnosis are spondylolisthesis, congenital narrowed lumbosacral canal and epidural tumors. Affections of the lumbosacral plexus can also give pain and neurological disturbances. It is often difficult to differentiate in an early phase between the pathological entities on clinical grounds only. Therefore, additional rontgenological investigation is necessary. A characteristic plain X-ray finding in our patients was a change of the bony structures of the spinal canal, for example erosion, scalloping and widening of the canal. The presence of congenital defects (38%) is remarkable. In a normal population open arches are seen in 4.4% at the Sl level, 1.7% at the L5 vertebra and in less than 1% at other levels4. The final diagnosis could only be made by myelography. If done by lumbar puncture the tumor is usually sufficiently delineated. When there is a total obstruction of the intradural space, a cervical puncture can be considered in order to show the cranial pole. Another possibility in such a case is to pass the tumor by a lumbar injection of air and watersoluble contrast medium under pressure’“. Following myelography, computerized tomography using the contrast medium still present can give more information about the nature of the

tumor, its intraspinal localization and an eventual extraspinal extension. Mostly cauda equina tumors are schwannomas or ependymomas, the dist~bution of which varies slightly among the different published series2,5s7.This is not in contradiction with our results. Little more than half of the tumors in our series constituted benign schwannomas. Total resection of all s~hwannomas, one ependymoma and one meningioma was achieved in our patients. Two patients with incomplete removal of an ependymoma were postopeIn the literature no ratively irradiated. consensus exists about the benifice of additional radiotherapy after subtotal resection of ependymomas. Van Duinen6 advocated to endeavour to total excision. However he did not conclude about a benificial effect of radiotherapy after incomplete removal of an ependymoma. Fearnside and Adams5 reported ‘acceptable results’ of radiotherapy after conservative surgery. From our small series no conclusions can be drawn about the long term effect of radiotherapy after subtotal excision. The prognosis of a cauda equina tumor seems to be strongly dependent on the histological type of the tumor, which on its turn determines the extent of the disability at time of operation. This relation is best shown by the differences in outcome in patients with a schwannoma and those with an ependymoma, and can be explained by an anatomical point of view. Schwannomas are intrinsic caudal root tumors and are therefore in general detected before extensive and destructive growth occurs. Ependymomas on the other hand, o~ginally centrally localized within the dural sac, compress caudal roots only after expansive growth (which explains the long pre-operative history). Expansive growth along the caudal roots reduces the chance of total resection and thereby influences the prognosis unfavourably. Finally ependymomas can morphologically change during their growth. According to Van Duinen6 and Slooff et al. ‘j, an ependymoma is originally encapsulated and starts growing diffusely later on. In our series patient nr. 9, with a pre-operative history of 13 years, had an encapsulated ependymoma. In patient nr. 10 with a history of 25 years, the tumor was growing diffusely, strongly adherent to the surrounding tissues. 347

Conclusion This study demonstrated the importance of early diagnosis of cauda equina tumors. Early detection enhances the chance of reversibility of the neurological disturbances and the possibility of complete excision. Unfortunately, early diagnosis is hindered by lack of specific symptomatology and the late onset of neurological signs. The course and nature of the pain will be helpful to the differential diagnosis with a lumbar disc syndrome. It’s the authors opinion that all patients suffering from a sciatic syndrome which reacts insufficiently to conservative treatment should undergo myelography . In a few cases this will surprisingly show the presence of a cauda equina tumor. In a later stage more extensive disturbances will make the differential diagnosis on clinical grounds easier but thereby worsen the prognosis. Both, the moment of diagnosis and the prognosis also depend on the rate of extension of tumor growth and thus on the histological type. Treatment of the tumors is surgical; modern surgical microtechniques may influence the prognoses favourably. The role of radiotherapy for ependymomas is unclear. In our group of 13 patients, two were reexplored within five years, demonstrating the necessity of sustaining post-operative follow-up.

348

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