Acta Ncurochir (Wien) (1987) 88:26-33 :Acta Ncurochirurgica �9 by Springer-Verlag 1987

Atypical Forms of Spinal Tuberculosis

Naim-Ur-Rahman 1, Kamal M. AI-Arabi 2, and Firoz Ahmed Khan 2

Departments of 1 Neurosurgery and of 2 Orthopaedics, College of Medicine, King Saud University, Riyadh, Saudi Arabia

Summary

Twenty-three patients with atypical forms of spinal tuberculosis treated between 1975 and 1985, are described.

All presented with signs and symptoms of compression of the spinal cord or cauda equina, ranging from paraesthesiae and increasing weakness of extremities to paraplegia and loss of sphincter control. None of them showed visible or palpable spinal deformity nor the typical radiographic appearance of destruction of the intervertebral disc and the two adjoining vertebral bodies. These atypical forms constituted about 12 percent of all the cases of spinal tuberculosis seen (a total of 190 cases); and fell into three well-defined groups: those with the involvement of neural arch only; those with the inolvement of a single vertebral body; and, those without bony involvement. The correct surgical approach in these groups was found to be different: spinal cord compression caused by the tuberculous disease of the neural arch was best treated by laminectomy; whereas single vertebral body disease required an anterior or anterolateral approach. Spinal computerized tomography was helpful in defining the extent of disease and planning the surgical approach. Histological confirmation of tuberculosis was obtained in all the cases and acid fast bacilli (A.F.B.) were found in, and cultured from, the biopsy specimens of 18 cases.

Keywords: Paraplegia; spinal compression; spinal tuberculosis; spinal computerized tomography.

Introduction

Spinal tuberculosis has become rare in the West bu t

it is still prevalent in Asia and Africa, where it is one of

the commones t forms of skeletal tuberculosis 1. Tuber-

culosis of the spine, in its typical form, is easily

recognized and treated. Classically, it is a disease of two

adjacent vertebral bodies with the dest ruct ion of the

in tervening interver tebral disc with or wi thout a para-

vertebral or a psoas abscess. Nar rowing and de-

s t ruct ion of the intervertebral disc is regarded as an

invar iable diagnostic feature of spinal tuberculosis as

opposed to ma l ignan t deposits in vertebral bodies in

which discs are unaffected.

The three unusa l forms described here are no t

sufficiently described in the medical literature. Perhaps

for this reason, there is delay in diagnosis and therefore

severe neurological deficit in a large n u m b e r of cases.

Because of the atypical features, the initial diangosis

was in error in 21 out of 23 of our cases. The commones t

misdiagnoses included pr imary and secondary tumours

of the spine. In two patients, the correct diagnosis was

suspected because of the presence of tuberculosis

elsewhere.

Patients and Methods

Twenty-three patients, aged 5 to 65 years have been treated for atypical forms of spinal tuberculosis at Lahore (Pakistan), ~enghazi (Libya), and Riyadh (Saudi Arabia) neurosurgical and orthopaedic centres during the last 10 years. These patients divide into three groups: 11 patients had the involvement of the neural arch only; 9 with involvement of a single vertebral body; and 3 presented as an intraspinal tumour without bony involvement (Table 1). All patients had surgical decompression and antitubercular chemotherapy was started as soon as the diagnosis was established.

Table 1. Atypical Forms of Spinal Tuberculosis

Type I Neural Arch Disease 11 cases Type II Single Vertebra Disease 9 cases Type III Intraspinal Tumour

without Bony Involvement 3 cases

Total 23 cases

Naim-Ur-Rahman et al. : Atypical Forms of Spinal Tuberculosis 27

Fig. 1. Location of the lesions in vertebral tuberculosis

Type I: Neural Arch Disease

There are a few published reports of the tuberculous process affecting the neural arch only with complete sparing of the vertebral bodies and intervertebral discs. Our series includes eleven such cases. Clinically, all these eleven patients showed evidence of spinal cord compression. Plane X-rays of the spine were reported to be normal in nine cases, but spinal CT-scans and operative findings confirmed the erosion of the neural arch in all cases. The disease affected the spines and laminae in five cases, transverse processes in two cases and pedicles in two cases. The remaining two patients had a more widespread destruction of the neural arch (Fig. 1). All these patients had a myelographic block at the level of the involved vertebra. Thus, the myelo- graphic block was at first and second cervical vertebrae in three patients, in the upper dorsal region in five patients, at 9th dorsal in one and at lumbosacral junction in two cases (Fig. 2). Compared with other large series of spinal tuberculosis, this vertical and horizontal distribution of the disease was atypical.

For example, Hodgson's 2 series of 587 cases showed maximal incidence at first lumbar vertebra with the incidence dropping above and below this peak; and none of his cases showed involvement of the neural arch alone.

All the patients with neural arch disease had lam- inectomy at the level of the myelographic block. Operative findings included varying degrees of erosion and replacement of the spines, the laminae, the trans- verse processes and the pedicles by grey, friable, tumour-like mass which invaded the muscles of the back and extended intraspinally to compress the spinal

Fig. 2. Vertical distribution of the lesions in eIeven cases of neural arch tuberculosis

cord. Operative decompression resulted in rapid im- provement of neurological signs and good functional recovery in all the cases.

Illustrative Cases

Case 1: A 30-year-old man presented with spastic tetraparesis and a firm swelling in the left occipital region. Tomograms showed destruction of the left lateral mass of atlas with evidence of rupture of the transverse ligament and backwards displacement of odontoid

28 Naim-Ur-Rahman etal. : Atypical Forms of Spinal Tuberculosis

(Fig. 3 a, b). CT-scan confirmed the fragmentation of the left lateral mass and adjacent posterior arch of the atlas with odontoid shift (Fig. 4). At operation, a tumour-like mass had replaced the left lateral mass and adjacent posterior arch of the atlas. After adequate debridement and decompression, posterior wiring and fusion stabi- lized this dangerous situation (Fig. 5). Histology revealed tuberculous granulation tissue. Postoperative recovery was rapid and complete.

Case 2. A 35-year-old man was admitted with a 2-month history . of severe right-sided brachalgia and progressive weakness of both legs. Examination revealed spastic Paraparesis and a sensory level at about the nipples. Myelogram showed a total block at the first dorsal vertebra. CT-scans at this level showed erosion and destruction of the spinous process, the lamina, the transverse process and the first rib on right side with a soft tissue mass (Fig. 6 a, b). At operation, a grey, friable, tumour-like mass was found to be invading the muscles of the back, destroying the neural arch, and compressing the dural tube. Operative diagnosis was a sarcoma, but histology showed tubercular granulation tissue and acid fast bacilli were found in it. Recovery of the neurological deficit was rapid and complete, following operative debridement and decompression.

Case3: A 33-year-old man presented with a 2-week history of paraparesis and urinary incontinence for 24 hours prior to admission. Physical examination revealed marked weakness of both legs, and a sensory level at about the umbilicus. Plane X-rays and myelogram showed destruction of the left pedicle of the 9th dorsal vertebra and a myelographic block by an extradural lesion at that level (Fig. 7). At operation, a friable turnout-like mass had destroyed and replaced the left pedicle and adjacent lamina of 9th dorsal vertebra. This mass extended backwards into the interspinal muscles and intraspinally to compress the spinal cord. Histology revealed tubercular granulation tissue. Neurological recovery was complete and rapid following decompression by laminectomy.

Case 4: A 30-year-old man was admitted with evidence of cauda equine compression and bladder dysfunction. Myelograms showed a complete block at the 5th lumbar vertebra (Fig. 8 a, b). At operation, a grey, friable mass had destroyed the back of the sacrum and extended anteriorly between the sacral nerve roots. As there was no evidence of caseation or suppuration, an intraoperative diagnosis of chordoma was made, and yet, histology revealed tuberculous granu- lation tissue.

Fig. 3 a and b. Tomographs showing destruction of the left lateral mass of the atlas, rupture of the transverse ligament and backward movement of the odontoid

Type II: Single Vertebra Disease

In this f o r m , a s ingle v e r t e b r a l b o d y is i n v o l v e d ,

r e su l t ing in its co l l apse a n d a r a d i o g r a p h i c a p p e a r a n c e

s imi la r to t ha t o f s e c o n d a r y c a r c i n o m a o f v e r t e b r a l

body . U n l i k e the c lass ical p i c tu r e o f sp ina l tube rcu los i s ,

the a d j o i n i n g i n t e r v e r t e b r a l discs a n d v e r t e b r a l b o d i e s

are n o t a f fec ted .

In o u r series, the bod ie s o f the 6th, 7th, 9th, 1 l t h ,

a n d 12th d o r s a l a n d 1st a n d 3rd l u m b a r v e r t e b r a e were

i n v o l v e d in 9 cases (Fig . 9). Al l these pa t i en t s h a d a

m y e l o g r a p h i c b l o c k a n d ev idence o f n e u r a l t issue

c o m p r e s s i o n a t the level o f the a f fec ted ve r t eb ra . C o r d

c o m p r e s s i o n in this f o r m o f d i sease is r a re ly i m p r o v e d Fig. 4. CT-scan showing fragmentation of left lateral mass of atlas with odontoid shift

Naim-Ur-Rahman et al. : Atypical Forms of Spinal Tuberculosis 29

Fig. 5. Postoperative X-ray showing pos- terior wiring. Note realignment of odontoid and anterior arch of atlas

by lamince tomy as shown by two of our earlier cases. In

the first case (Case 5), there was worsening of neurolog-

ical status and, in the second, there was little improve-

ment following laminectomy.

The anter ior t ransthoracic or anterolateral

approach yielded effective exposure and decom-

pression in six of these cases and was followed by

satisfactory neurological recovery. One pat ient (Case 6)

had only a needle biopsy followed by ant i tubercular

therapy.

Illustrative Cases

Case5 . A 26-year-old woman was admitted with a 3-month history of increasing weakness of both legs and intermittent in- continence of urine. She had hypoaesthesia up to the level of xiphisternum and a spastic paraparesis. Spinal X-rays showed collapse of the body of the 6th thoracic vertebra (Fig. 10). No abnormality of adjacent intervertebral discs or vertebrae could be detected. Myelogram showed a block at the level of the collapsed vertebra (Fig. 1 I). A diagnosis of secondary carcinoma was made and laminectomy was carried out. At operation, granulation tissue and caseous material was found to be compressing the cord from the

Fig. 6 a and b. Spinal CT-scans showing erosion and destruction of the spinous process, the lamina and the transverse process on the left side

30 Naim-Ur-Rahman et al. : Atypical Forms of Spinal Tuberculosis

Illustrative Case

Case 7: A 65-year-old man was admitted with a history of progressive paraplegia for two weeks and urinary incontinence for 48 hours prior to admission. Physical examination revealed moderately. dense paraplegia and a sensory level at about the umbilicus. Plain spinal radiographs were normal. Myelogram showed a complete block due to an extradural lesion at 9th dorsal vertebra (Fig. 13 a, b). Preoperative diagnosis was "metastasis" but laminectomy revealed a cuff of extradural tumour-like tissue surrounding, displacing and compressing the cord. Histology again showed tubercular granu- lation tissue. Postoperatively, there was rapid recovery of the neurological deficit and he could walk independently 2 months later.

Fig. 7. Destruction of the left pedicle of D-9 and a myelographic block at that level

front. Satisfactory debridement of the anterior compressive agents was not found to be possible without undue retraction of the cord. After laminectomy, her paraparesis became dense and she became incontinent. 24 hours later through an anterolateral approach a second operation was undertaken and an effective anterior decom- pression performed. Postoperatively, she remained paraplegic for many months. Recovery was slow and incomplete.

Case6: A 40-year-old man developed signs of cauda equine compression. Spinal X-rays showed a lytic lesion in the body of the 3rd lumbar vertebra with normal intervertebral discs on either side (Fig. 12). An initial diagnosis of metastasis was made. As the patient refused operation, a needle biopsy was carried out and revealed tuberculous granulation tissue. Inspite of vigorous antitubercular therapy for one year, the improvement of neurological status has been slow and incomplete.

Type IIl: Intraspinal Tumour Without Bony Involvement

Three patients had progressive paraplegia wi thout any radiological evidence o f a bony lesion in the spine.

All the three had a myelographic block corresponding to the clinical level o f cord compression. Initial diag-

nosis o f metastasis was made in all o f them.

Discussion

A search o f the literature was made to find an

explanat ion for this unusual distribution o f tuberculous

disease o f the spine, where it was confined to the neural

arch or to a single vertebral body with complete sparing

o f adjoining intervertebral discs. The following facts

emerge: in pyogenic osteomyelitis, the spine is involved

in under five percent o f cases while in skeletal tuber- culosis, it is involved in 58.7 percent 2. I f pyogenic

osteomyelitis is an arterial b lood-born disease, can

mycobac te r ium tuberculosis spread by the same route

and give such a marked difference in percentage o f

involvement? This could be explained if the tubercle

bacillus and the vertebra had some special affinity for

each other. But all a t tempts to produce spinal tubercu- losis in experimental animals by injecting mycobac-

terium tuberculosis locally into the vertebrae and into

the left ventricle o f the heart have failed to produce any

spinal disease 3. The explanation suggested is that a

different pathway of spread, either venous o f lymphat-

ic, might occur in spinal tuberculosis. In a series o f animal experiments in which organs in the abdomen

and pelvis were injected with mycobac te r ium tubercu-

losis, it was possible to produce a pr imary infection in

the injected organ, usually the kidneys, and a secondary

lesion in the spine 4. By making sections o f these

animals, it was possible to trace the infection f rom the

kidney to the spine via the four th venous plexus" it was found to penetrate the spinal canal and pass upwards

along the vertebral veins and could produce lesions in vertebrae at a higher level 4. I t is now generally accepted

that infection travels to the spine by way of the venous pa thway suggested and described by Batson 5, 6, Henriques 7, and others 8, 9, 10. The posterior external

venous plexuses o f the vertebral veins are placed on the

poster ior surfaces o f the laminae and a round the spinous, transverse and articular processes. They anas- tomose freely with the other vertebral venous plexuses

Naim-Ur-Rahman el al. : Atypical Forms of Spinal Tuberculosis 31

Fig. 8a and b. Myelograms showing complete block at L-5 in a patient with tuberculosis of the sacrum

and constitute the final pathway for infection to reach the neural arch in the atypical form of spinal tubercu- losis in which it is solely involved. When atypical

tuberculosis presents as intraspinal tumour without bony invovlement, infection is brought to the epidural

space by the internal vertebral venous plexus which consists of a plexus of thin, walled, valveless veins which surround the dura mater of the spinal cord like a basketwork 1l. In the single vertebra disease, the inter-

vertebral disc does not become involved as a pr imary focus as it is an avascular structure. The textbook description that the narrowing and destruction of the intervertebral disc is an early sign of spinal tuberculosis is true, but the deduction that "therefore, the interver- tebral disc is involved primarily in the disease", is not

so. What takes place is that the vertebral bodies on either side of the disc are infiltrated with granulation tissue and lose their blood supply and the disc loses its nutrition and becomes narrow. In the single vertebra disease described here, nutrition of the disc continues from the side of the healthy vertebra and hence the disc stays normal.

C I - - 2 - - 3 _ _

4 - -

No. of Coses

0 i 2 I I I

9 IO I I - - 12

- - L - t 2 - -

S - - I m

- 3 - -

I

m IIIII

- - m

Fig. 9. Vertical distribution of the single vertebra disease

32 Naim-Ur-Rahman etal. : Atypical Forms of Spinal Tuberculosis

Fig. 10. X-rays of dorsal spine showing collapse of the body of the 6th thoracic vertebra with no abnormality of the adjacent interver- tebral discs

Spinal computed tomography (CT) has been found to be an important diagnostic tool. CT-scanning, along with metrizamide myelography was helpful in evaluat- ing the anatomy of subarachnoid block in patients without bony involvement. Spinal CT detected small lesions in the neural arch much earlier than plain X-rays and it also provided a detailed picture of the extent of bony destruction especially in neural arch disease. This information was found to be helpful in planning the surgical approach.

These atypical forms of spinal tuberculosis must be differentiated from malignant extradural tumours, es- pecially the spinal epidural metastasis where the pri- mary remains occult in about 17 percent of cases 12. This differentiation can be difficult even at the time of operation due to atypical tissue reaction to mycobac- terium tuberculosis, as was seen in some of our cases. Therapeutically, antitubercular chemotherapy and sur- gery continue as the mainstays of management. The direction of the surgical approach is governed by the location of the disease and neural compression. Thus, the correct approach for the neural arch disease was found to be laminectomy, while the anterior or antero-

Fig. 11. Myelogram showing a complete block opposite the col- Fig. 12. Spinal X-rays showing a lytic lesion of the body of the 3rd lapsed vertebra lumbar vertebra with normal intervertebral discs on either side

Naim-Ur-Rahman etal. : Atypical Forms of Spinal Tuberculosis 33

Fig. 13 a and b. Myelograms showing complete block due to extradural lesion at 9th dorsal vertebra, with no evidence of bony involvement

lateral approach was found to be superior for single vertebra disease.

To conclude, these atypical forms of spinal tubercu- losis are not uncommon and are sometimes misdiag- nosed and mistreated as primary or secondary spinal tumours. There is an increasing tendency to treat "malignant extradural tumours" with primary radio- therapy without tissue diagnosis. We suggest that surgical decompression and biopsy should be carried out in all suspected cases of spinal metastases, especial- ly when the primary is occult, and particularly, in the regions where tuberculosis is common.

References

1. Naim-Ur-Rahman (1980) Atypical forms of spinal tuberculosis. J Bone Joint Surg [Br] 62B: 162-165

2. Kulowski J (1936) Pyogenic osteomyelitis of the spine. An analysis and discussion of 102 cases. J Bone Joint Surg 18: 343- 364

3. Blacklock JWS (1957) Injury as an etiological factor in tubercu- losis. Proc R Soc Med 50:61-68

4. Hodgson AR (1975) The Spine. Rothman RH and Simeone FA (eds) Vol 11, Chapter 12, pp 567-595. WB Saunders Company

5. Batson OV (1940) The function of the vertebral veins and their role in the spread of metastases. Ann Surg 112:138-149

6. Batson OV (1957) The vertebral vein system. Caldwell Lecture, 1956. AJR 78:195-212

7. Henriques CQ (1958) Osteomyelitis as a complication of urology. Br J Surg 46:19-28

8. Clemens HJ (196i) Die Venensysteme der menschlichen Wirbels/iule. De Gruyter, Berlin

9. Herlihy WF (1947) Revision of the venous system, the role of vertebral veins. Med J Aust I: 661 672

10. Herlihy WF (1948) Experimental studies in the internal vertebral venous plexus. Essays in Biology 151

11. Anderson JE (1978) In: Grant's atlas of anatomy, seventh edition. Williams & Wilkins, Baltimore

12. Black P (1979) Spinal Metastasis: current status and recom- mended guidelines for management. Neurosurgery 5:726 745

Authors' addresses: Naim-Ur-Rahman: F.R.C.S. (Eng), F.R.C.S. Ed. (Surgical Neurology), Associate Professor of Neurosur- gery, 24-B-I, Satellite Town, Rawalpindi, Pakistan. Kamal M. Ai- Arabi: F.R.C.S. (Eng), F.R.C.S. (Edin), Associate Professor of Orthopaedics, Firoz Ahmed Khan: F.R.C.S. (Glasg), F.R.C.S. (Edin), Assistant Professor, Department of Orthopaedic Surgery, College of Medicine, King Saud University, Riyadh, Saudi Arabia.