Patient 2: A 45-year-old man was admitted to
our institution on the 1/10/94 because of progressive difficulty with walking.
There was no history of spinal trauma, but he had been complaining of mid-back
pain for almost 3 years. He had also noted urinary incontinence. At admission
physical examination showed hypoesthesia T11 and below, motor paralysis
of the lower extremities predominantly in the left leg. The deep tendon
reflexes were exaggerated in the lower extremities and Babinski’s sign was
bilaterally positive. Routine clinical examination was without abnormality.
Plain films showed narrowing thoracic disc at the level of T11-T12. MRI
revealed thoracic disc degeneration and prolapse of a herniated disc material
into the spinal canal. There was also a high intramedullary signal on T2-weighted
images facing the herniated disc (Fig. 4). Based on these findings, TDH
at T11-T12 was diagnosed. On 10/10/94 surgery was done. Through a posteolateral
approach a costrotransvesectomy was made, and a herniated disc that prolapsed
into the epidural space through the posterior longitudinal ligaments was
observed, the herniated mass was excised. Post-operative course was without
abnormalities. The patient made a good recovery and is at present, about
5 years later, fully ambulatory with marked improvement in leg strength.
However, some lower extremity spasticity has persisted.
Patient 3: A 48-year-old patient presented with rapid onset
of difficulty in walking. He had spinal trauma one month previously. The
patient had also noted urinary incontinence. Upon neurological examination,
there was a partial sensory level at T8, whereas proprioception, vibration
and temperature were normal throughout. Both lower extremities were markedly
spastic and muscle strength was graded 4/5 bilaterally. Deep tendon reflexes
were exaggerated in the lower extremities and plantar responses were upgoing.
Plain thoracic films showed a narrowing T8-T9 intervertebral space. Myelogram
revealed an anterior block at T8-T9 intervertebral level. CT scan after
myelography showed a soft tissue tumour compressing the anteromedial surface
of the spinal cord. The diagnosis of TDH at T8-T9 was suggested and the
patient was operated on through the posterior approach. T8 and T9 lamina
were removed and the dura opened. The spinal cord was carefully retracted
laterally and herniated disc was removed. The post-operative course was
uneventful, progressive recovery with rehabilitation was observed after
8 months. The patient was able to walk and his neurological examination
revealed only a slight hypoesthesia in the lower extremities.
Key reported the first case of spinal injury from a thoracic disc herniation
in 1838.5 Over the past 30 years alternative surgical approaches to thoracic
disc herniation have been reported and widely used, which significantly
reduced the morbidity of the surgical treatment of this disease.(3) In addition,
modern diagnostic technologies showed that the incidence of TDH is higher
than previously suggested. Autopsy studies have suggested an incidence between
7-15%.(3) Clinical studies showed that it accounts for about 0.2-2% of all
disc operations.(7,11) Otani attributed the low incidence to few quantitative
and dynamic factors in the thoracic nucleus pulposus.(11) The most frequent
site of this disease is the lower thoracic spine, especially T11-T12.(3,8,11)
In our series, the site of TDH was below T8 (T8-T9, T10-T11 and T11-12).
Patients aged between the 4th and 6th decades are most often affected.(5,3,11)
Spinal trauma can reveal this affliction.(3,5 )In our series we noticed
it in 2 cases (Case 1,3). Clinical symptoms consist of spinal cord or nerve
root compression.(14) The pain from TDH usually radiates to the lumbar region,
the midline of the back near the affected disc, or in a radicular pattern
around the chest wall. This pain is variable. Whitcomb reported a case of
TDH in a patient with chronic pancreatitis who recovered after disc removal.(14)
Pain patterns vary according to the level of herniation and distribution
of affected spinal nerves. Other signs and symptoms are motor weakness sensory
loss or bowel and bladder disorders. Abnormalities in the physical examination
usually reflect significant myelopathy with paraparesis or paraplegia.(3,14)
Once TDH is suspected the diagnosis should then be confirmed by MRI or CT
myelogram.
MRI with sagittal T1 and T2-weighted image and axial T1-weighted image is
the investigation of choice of TDH.(6,7,13) It reveals disc herniation and
spinal injury with intramedullary high signal. However, CT scan is also
useful to show disc herniation and the importance of calcifications which
are seen in 52-75% of cases.(1,8) Myelogram is mandatory to show anterior
block facing the diseased intervertebral disc.
Numerous approaches are used to excise TDH.(8) These could be anterolateral,
posterolateral, lateral, posterior and thoracoscopic approaches. Key determinants
in selecting an approach among these alternatives should be: 1) the anatomic
location of the herniated material, 2) the general health of the patient,
and 3) the surgeon’s experience.
The initial approach, which achieved disc resection through laminectomy,
was associated with very high morbidity and mortality and was, therefore,
abandoned.(3) The transpedicular approach has the advantage of being a relatively
pure posterior approach that exposes the spinal cord and nerve roots.(3,8)
Costotransversectomy is also an excellent approach for lateral thoracic
disc herniation. It gives relatively limited exposure of the anterior elements
of the spinal cord.3 With these last two approaches, no mortalities have
been reported and increased paresis or paralysis has also been minimised.
The transthoracic approach is the most suitable route to excise TDH. It
provides a wide angle view to the surgeon. The posterior half of the body
and herniated disc can be removed safely under direct vision.(3,8) However,
it is not possible for TDH above the T4 level and carries a substantial
risk of pulmonary complication.(8) Another difficulty with this method occurs
with disc herniation to the left side because the heart and great vessels
hinder the approach.(3) This approach respects the posterior structures
avoiding unnecessary bone, muscle, or nerve removal. It provides more complete
neurological recovery in patients with myelopathy.(2,8,11)
Indication for treatment of TDH, with neurological symptoms are clear in
literature.(3,7,8) Prompt surgical treatment is the appropriate choice.
The transthoracic approach is the most recommended for all TDH below T4
level except for patients with serious pulmonary compromise.(3,4,7,8,10)
The thoracoscopic approach provides exposure of the thoracic disc equal
to that of thoracotomy but with minimal morbidity directly attributable
to the “approach” itself.(12)
Conversely, there is no general rule on the treatment of TDH causing pain
without myelopathy. It may be acceptable to apply the standards used in
cervical or lumbar disc herniation. First line therapy includes bed rest,
physical therapy and non-steroid analgesic medications for several weeks.
Spontaneous resolution of TDH are reported.(7) Conservative treatment in
these cases, is first advised.
Early diagnosis and refined surgical techniques will lead to further improvements
in the treatment of thoracic disc herniations.
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