Introduction
Since I had to leave Saint- Claude Camp Jacob General Hospital in Basse-Terre as it closed 40 out of its 60 surgical beds in 1989, there was a sudden developement and change in diagnosic imaging.
Some of these technologies use new physical priciples like MRI, others were developed using computerized processing of information gained by well known methods such as reconstruction of CT scans.
Older and well established methods like conventional x-ray imaging, tomography and myelography (Dr JCW) are still available.
This situation gave me reason to reevaluate the position of these techniques in our clinical management, especially in the acute setting.
Diagnostic approach
The diagnostic approach to acute para and tetraplegia lined out in the following diagramms is based on my experience as Chef de Clinique Assistant with patients from year 1964 to year 1980 in Paris best spine centers.
To define a pragmatic and clinically relevant way of using diagnostic procedures it is a must to have a clear scheme of differential diagnostic possibilites.
Spine Imaging Decision Tree
This is why I propose this decision-tree…
A patient presenting with an acute paraplegia may or may not have been exposed to a trauma.
I will first focus on the majority of patients in Camp Jacob Hospital which had suffered a trauma.
The important question is whether the trauma was
- adequate – such as a car or motorcyle accident – or
- inadequate – like lifting a case of bottles or kicking a spade.
If there was a “adequate trauma” (the two Galion Bus Accident of january 10th 1984 and 1985…), I look for destructed vertebrae – that is
- fractures – and/or
- destructed soft tissue which are disc herniations and ruptures of ligaments.
Additional possibilites are intraspinal bleeding or a spinal contusion.
If there was a trauma, I consider as inadequate compared to the damage to the spine, I look for destruction of vertebra because of osteoporosis, tumors or spondylitis.
Other possibilities which involve no destruction of vertebra are arachnoitis, discitis, stenosis of the spinal canal or adhesions of the spinal cord.
If the patient reports no trauma at all, there might be
An acute inflammation or any kind (HTLV) of neurologic disease producing the symptoms of para- or tetraplegia also have to be considered.
Finally, there is always the possibility of a trauma which the patient does not report.
A diagramm will soon demonstrate the frequency of the conditions that led to paraplegia in patients I admitted for primary care during all these years.
The vast majority of paraplegia was caused by fractures.
Other important groups were tumor and disc problems.
Imaging strategy – adequate trauma
One Imaging Strategy
I outline here one diagnostic strategy in patients with an adequate trauma.
The first thing – which is always nescessary – is to get plain film x-rays of the segment of the spine which corresponds with the neurologic staging.
I know of a “second hand trauma case” who left the university hospital with high dorsal paraplegia from a T2 displaced fracture and had had “only” diagnosed a T12 undisplaced fracture with “no compression CT” at T12 level and finally no proper managing : spine palpation and full history in hurry was probably omitted.
When I was on duty at Camp Jacob, the patient should and DID not leave the x-ray department without (if possible) palpation guided readable films in two planes and dynamic lateral cervical flexion views supervised by me.
In almost all cases at least the presence of fractures (if not by palpation !) could be diagnosed on these films.
The next step depends indeed on the overall approach to the management of these fractures.
One or two each year in a 120 000 population
Since I do intend to stabilize all instable spinal fractures as soon as possible (with an anterior and posterior approach if appropriate) – a film showing an instable spine as demonstrated here would at that time, give me enough information to proceed with surgery.
From 1983 to June 1989, I managed one case each year of these traumatic paraplegia (Galion falls, coco tree falls, windows fall).
If the fracure does not appear to be unstable or for example only a posterior stabilisation is discussed, a CT-scan should be obtained, to give the nescessary information about intraspinal fragments, fractured pedicles as well as traumatic herniations of intervertebral discs.
The above picture demonstrates one of these common cases where the plain film does not show too much of a stenosis of the spinal canal through fractures.
Only the CT – Scan would reveal the extend of an intraspinal fragment, I finally found during surgical approach.
In our Camp Jacob cases, these fractures were still reduced using a Roy-Camille Screw and Blade Internal System, whereas a Cotrel Dubousset System (used later for tumors) would have been much easier to manage….
Clinical results, very good although not controlled intraoperatively by myelography nor later with a CT-scan
The very good clinical results were neither controlled intraoperatively by myelography but using a flouroscope nor later documented with a CT-scan, as I would probably do now.
In one case (first Galion accident of Jan, 10th,1984) of a T7 burst fracture with complete and resolutive paraplegia, preop CT scan (no CT at that time) would have shown a sharp pedicle bit pinned in the middle of the spinal cord.
According to this experience of mine, 3D reconstructions would not have yield any additional information.
It should be mentioned at this place that according to experience, most surgeons in the late 90ties did stick to the plain films while they were performing the surgery – even if CT-scan or MRI scans were beginning to be available.
In cases where no definite fracture could be seen on the conventional x-ray films, many authors would still follow in the late 90ties a conservative stepladder of diagnostic imaging including
- CT-scans,
- Myelography and
- repeated CT-scan after Myelography.
However, MRI would still be employed as a last resort.
The growing experience, gathered from my own last 15 years MRI-Studies changed that.
I learned reading clear but painful "myélographie gazeuse" with the La Pitié Paris Hospital Fischgold-Metzger-Aboulker team in... 1967
I start now with MRI imaging and feel confident to use it to diagnose soft tissue problems – for example disc herniations, as demonstrated above as well as fractures.
According to my “recent” experience, MRI is by no means “boneblind”.
Of course other conditions, such as intraspinal hemorrhage or edema following spinal contusion are also demonstrated precisely.
Only when Magnetic Resonance Imaging would be not possible or not available we would still use a combination of Myelography and CT scanning, as we had to do in the 80ties at Camp Jacob Hospital.
Imaging strategy – no adequate trauma
If there was no or no adequate Trauma, I still do plain film x-ray studies as described above, to diagnose destructed vertebra and tumor or spondylitis induced fractures.
If these films or the patient history indicate a possibility of muliple lesions – such as a kown prostata carcinoma – I obtain a MRI because it provides a fast overview to the extend of the disease.
It also shows details of the impact to the spinal cord.
If it is reasonable to expect only a single lesion I would do a CT-scan.
CT scans might be very reliable to define the extend of intravertebral lesions and show the remnants of a vertebra with metastasis.
If no fractures are visible and intraspinal changes such as tumors or hemorrhage are to be diagnosed, I proceed with an MRI-Scan.
As example : bleeding ependymoma which caused a paraplegia with an acute onset.
Summary
I would summarize frequent problems we encoutered.
First points
I underscore that imaging diagnostic has to be based on exact clinical neurological staging.
Usually minor neurological deficts are missed, which are present in neurologic segments above the level of the dominating symptoms.
This problem is especially important if the patient is unconscious, intoxicated or suffered a headinjury.
Second fractures are missed usually because a lesion is found, which seems to “explain” the symptoms (CHU one case).
It is important to keep this in mind and to look for associated fractures if the circumstances of the injury indicate the possibility.
An especially difficult area for conventional x-ray imaging is the cervico-thoracic transition.
With an x-ray image not demonstrating all seven cervical vertebrae, I was once called for a complete C7 dislocation in a young paraplegic motobike suspected of pithiatism by the general surgeon on duty…
We can only support that these important X rays (as well as immediate dynamic lateral flexion views should be done in spine surgeon’s presence, when there is a good chance of a fracture or luxation of the lower cervical spine or in any case of cervical spine trauma as I instituted this in Camp Jacob with very reactive radio technicians in the 80ties..
If it is impossible to obtain readeable images by applying traction to the shoulders, a conventional midline tomography might be done, but in my extensive experience plain X rays would be enough..
Concerning CT-scans there still might be three frequent problems.
The first is a missing topogramm.
If the topogramm is missing, there is always an incertainty where exactly the scans were done and where the lesion extends.
Another mistake is a CT-scan which is only documented in a bone window.
Patients with traumatic disc herniation may be missed out of this reason.
The last point regarding CT scans which lead to missing of lesions is an inappropriate gapping between slides.
I recommend a maximum slice thickness of 2 to 3 mm with no gap if a study of the cervical spine is done.
To achieve this, a restriction of the examination area to two or a maximum of three cervical segments might still be often necessary.
As a last point we would like to warn against elaborate additional studies and reconstruction processes.
Once you have the nescessary information you should terminate diagnostic imaging.
As said earlier, I do not see yet in 2009 any benefit in added information if a time consuming 3D reconstruction is done.
Frequent problems with imaging methods
Common problems
The imaging is focused on a wrong soinal segment due to incorrect neurological staging
Additional fractures are missed
Conventional X-ray imaging
Fractures of the cervico-thoracic transition are missed because the 7th cervical vertebra is not properly demonstrated
CT-scans
Missing topogramm
Gap between the scans too wide (especially in the C-spine)
No soft-tissue window generated
CT- and MRI-scans
Elaborate reconstruction yielding no additional information
