D1 SPINAL KOCHS ó THE HIDDEN ZONE
A Bonshahi*, M Warke*, A Malik**, A Prekh***
*Sr. Registrar; **Lecturer; ***Prof. and Head, Dept. of Orthopaedics, BYL Nair Ch Hospital, Mumbai.
Spinal tuberculosis the most common form of osteoarticular tuberculosis, widely prevalent in our country and very varied in presentation is however detected easily on X-rays. We have the opportunity to present an interesting case in which special X-rays and an MRI scan were required to detect the lesion.
50% of all cases of osteoarticular tuberculosis affects the spine. Various authors have presented many regional distribution statistics. The commonest region of involvement is the dorsal followed by the lumbar and dorso-lumbar region. Involvement of the cervicodorsal region being less than 5%. The incidence of tuberculosis is on the rise, with the added contribution of HIV infection, makes these cases even more important to detect early.
A 28 year old female patient presented to us with a history of gradual onset of difficulty in walking with history of constitutional symptoms over a period of 3 weeks.
Examination at presentation revealed a paraparesis with signs of upper motor neuron disease. Sensory hypoaesthesia was present upto the D8 level. There was no clinical deformity of the spine except for a diffuse tenderness in the cervico-dorsal region. Routine X-rays of the entire spine, failed to reveal any spinal deformity or a soft tissue abscess.
A Swimmers view of the C7-D1 region showed a partial collapse of D1 vertebra. AKT was started and the patient was applied Halterís traction.
Within a few days the motor power deteriorated to paraplegia with bladder and bowel involvement and sensory level persisting at D8 region. This sensory level could not be explained.
An MRI scan was done which confirmed the level and ruled out any other area of involvement.
Surgical decompression via supraclavicular approach was done with placement of a tricortical iliac crest graft. Post operatively we encountered no complications. Bed rest in a Halterís was given for 8 weeks.
At present, 6 months post-operatively the patient has full recovery except for an equivocal left plantar reflex.
Vertebral tuberculosis commonest during the 1st three decades with equal sex distribution has a regional predilection. Dorsal spine is involved in 42% of cases followed by lumbar in 26%, dorso-lumbar in 12%, cervical 12%, cervico-dorsal 5% and lumbo-sacral in 3% of the cases.
Within this regional distribution, the paradiscal regions are most commonly involved with anterior, central and posterior elements accounting for less than 2%.
Most cases present with typical clinical features of pain, stiffness of the spine and constitutional symptoms. The findings on examination in order of frequency are; kyphosis (95%), cold abscess (20%), and neurological involvement (20%).
Neurologically the patient may present as - early onset paraplegia (within 2 years), or
- Late onset paraplegia (after 2 years).
Early onset variety is due to cord oedema, tubercular granulation tissue, caseous material or rarely due to ischaemia to the cord.
Late onset paraplegia is due to mechanical pressure on the cord or due to a recrudescence of the disease. The former is having a better prognosis.
Radiologically on an average, 2 to 3 vertebrae are involved. Changes are detected within a few weeks of onset of symptoms. Abscess shadows in the cervical region shows an increase in the space between the pharynx and spine in the lateral X-ray. Normal being 0.5 cm at the level of the cricoid cartilage and 1.5 cm below that level.
The patient we are reporting had an early onset paraplegia with no evidence of any deformity in the spine and sensory level at D8. However tenderness was present at the cervico-dorsal level and the Swimmers view showed D1 involvement which could not be explained. Routine X-rays both AP and lateral were normal. Normally any X-ray in the C7-D1 region, fails to show a clear outline of D1 vertebrae in the lateral plane, making it a hidden zone which can be revealed by a Swimmers view. However in our case not only the routine X-rays but clinical findings too did not give a clue to the level of involvement. With neurological deterioration and the inability to explain sensory level, MRI scan was done which revealed the partial collapse of D1 vertebra and soft tissue abscess compressing the cord.
Surgical exploration was decided when the patient deteriorated neurologically in the wards. The usual approaches to this region are - anterior trans-sternal, trans-pleural through bed of 3rd rib or an anterior low cervical supraclavicular approach.
We preferred the supraclavicular approach. Decompression of the cord was achieved and a tricortical iliac crest graft was placed in the defect.
Post-operatively the patient was immobilised in a Halterís traction. Mobilisation after partial motor recovery in a Philadelphia collar was done at 8 weeks. At present the patient is clinically almost normal except for an equivocal plantar on the left side at 6 months. Thus we conclude that although routine X-rays of the spine do not show any abnormality in the cervico-dorsal region one should take special X-rays notably the Swimmers view or MRI/CT scan inspite of lack of correlation in clinical findings - to reveal the hidden zone.
We would like to thank the Dean, BYL Nair Hospital for allowing us to conduct this report.
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