La lumbosciatica is a condition characterized by pain in the lower back that radiates to the lower limb following the course of the nerf sciatica (the nerve that controls the entire lower limb).
It is due to compression or irritation of this nerve by a pathological process, a herniated disc lumbar in the vast majority of cases.
In general, sciatica is benign et spontaneously regressive in a few weeks to a few months thanks to a simple conservative treatment (rest, analgesics, anti-inflammatory, physiotherapy, etc.).
But sometimes, we can have to deal with complicated shapes lumbosciatica which require emergency care! We can mainly cite the hyperalgesic lumbosciatica, lumbosciatica paralytic and lumbosciatica complicated by cauda equina syndrome.
In this article, we will talk about one of these complicated forms: the paralyzing lumbosciatica.
Lumbar spine: some notions of anatomy
The lumbar part of our spine consists of 5 vertebrae voluminous: L1, L2, L3, L4 and L5. Each of these is made up of a vertebral body forward and a spinal blade (or posterior arch) back.
Between each pair of adjacent vertebrae is interposed a fibrocartilaginous structure called « intervertebral disc ». The latter acts as a shock absorber during body movements and gives flexibility to the spine.
Each vertebrate lumbar is dug in its center with a hole called "vertebral foramen". The stacking of the lumbar vertebrae and the superposition of their vertebral foramina create a kind of bone tunnel: the Spinal canal lumbar, crossed by the terminal part of the spinal cord.
The spinal cord, in its lumbar part, gives rise to roots nerve which emerge from the lumbar canal via foramina located on each side of the vertebrae.
These nerve roots then form an anastomotic network (fusion of different nerve fibers) called "lumbosacral plexus". The latter, in turn, gives rise to a nerve of great caliber: the sciatic nerve.
Le sciatic nerve and its various ramifications are responsible for motor and sensory innervation of the entire lower limb. When it is compressed or irritated, pain appears on its path: the famous sciatic neuralgia!
What is lumbosciatica?
La lumbosciatica is a condition that combines sciatic neuralgia (lower limb pain that follows the path of the sciatic nerve) and lumbago (lower back pain).
In the vast majority of cases, lumbosciatica is the result of a disco-radicular impingement (pathological interaction between a nerve root and an intervertebral disc) caused by a herniated disc.
Other pathologies can also cause, more rarely, lumbosciatica, in particular a tumor process (benign or malignant tumor developing within a lumbar vertebra), a process infectious (spondylodiscitis), A inflammatory process (rheumatic diseases)…
Sciatica is clinically manifested by:
- Turnkey low back pain et sciatica favored by physical exertion, coughing, sneezing and any maneuver that increases intra-abdominal pressure.
- Pain triggered or accentuated by stretching the leg. It is possible to objectify this characteristic thanks to the Lasègue maneuver during the doctor's clinical examination.
- Turnkey sensory disorders such as numbness, tingling, tingling or changes in skin sensitivity (hypoesthesia, anesthesia, hyperesthesia) in the lower limb or genital area.
- Turnkey motor disorders such as loss of muscle strength in the lower limb. In the most severe cases, an authentic paralysis can set in, we then speak of paralyzing lumbosciatica.
Other symptoms such as fever, fatigue, loss of appetite, for an significant unexplained weight loss ou deterioration of general condition can be encountered in front of sciatica. Their presence should suggest rarer pathologies (other than a simple herniated disc), in particular a cancer (primary or secondary) or a bone infection.
Paralyzing lumbosciatica: what particularity?
La paralyzing lumbosciatica is a complicated lumbosciatica of a motor deficit less than 3 according to MRC scale (Medical Research Council of Great Britain).
The MRC scale is used to assess muscle strength as following :
- 5: normal muscle strength.
- 4: muscle strength sufficient to support the weight of the limb and to overcome resistance.
- 3: muscle strength sufficient to support the weight of the limb, but insufficient to overcome resistance.
- 2: muscular strength sufficient to allow movement, but on condition that gravity is eliminated.
- 1: barely perceptible movements, muscle contraction possible.
- 0: no movement or muscle contraction (complete paralysis).
As mentioned above, the paralyzing lumbosciatica is characterized by a motor deficit immediately rated at 3 (or less) according to this scale, or a progressive motor deficit (increasing muscle weakness, worsening of a motor deficit already present).
Paralytic lumbosciatica accounts for approximately 3% of all sciatica, so it is relatively rare. On the other hand, it concerns up to 14% of operated sciatica, usually appearing within two weeks of surgery.
How is the diagnosis of paralytic lumbosciatica made? ?
When a patient complains of lumbosciatica, the doctor begins by questioning him minutely in search of anamnestic elements that will allow him to make the diagnosis lumbosciatica and move towards a common form (by herniated disc, usually benign) or specific (tumor, infection, fracture, etc.).
He will then proceed to a complete physical examination, with particular attention to neurological and spine examination, in order to objectify and characterize (intensity, topography, triggering factors, etc.) the various symptoms of lumbosciatica (sciatica aggravated by the Lasègue maneuver, etc.).
It is also during the clinical examination that the doctor will be able to highlight a motor deficit thanks to a muscle testing of the lower limb (assessment of muscle strength using the MRC scale).
In front of a MRC grade less than 3 (or progressively worsening), the diagnosis of paralyzing lumbosciatica will be asked from this phase of the diagnostic process (even before carrying out any additional examination).
In the case of paralyzing lumbosciatica, the advice of a spine specialist is needed within the first 24 hours. The latter will perform imaging (most often lumbar MRI, because it is more efficient than the scanner to study the soft tissues) in order to specify the cause of crippling lumbosciatica (tumor, infection, massive disc herniation or not).
What to do in the face of paralyzing lumbosciatica?
In front of a paralyzing lumbosciatica, it is essential tohospitalize the patient urgently, preferably within a specialized surgical unit in the spine.
It will then beaccurately assess the motor deficit, as well as the other symptoms (pain, sensory disturbances, etc.), and to carry out imaging examinations (MRI or lumbar scan) to discuss a rapid surgery.
NB: performing imaging examinations should not delay treatment, because late treatment causes the patient to lose chances of healing more quickly.
You should know that the degree of muscle deficit or the intensity of the pain does not reflect the severity of the lesions. A patient may very well have total paralysis of the lower limb while presenting only a small disc herniation (and vice versa).
The goal of supporting the paralyzing lumbosciatica is relieve nerve root compression (or nerve roots). For example the cure of a lumbar disc herniation, removal of a displaced bone fragment (fracture), theexcision of a tumor, drainage of an abscess…
It is important to clarify that surgery is not systematic before paralyzing lumbosciatica. Conservative (medical) treatments, including corticosteroid injections, may be sufficient to achieve clinical improvement in about half of the cases.
Surgical intervention should be discussed on a case-by-case basis by specialized doctors in the management of spinal pathologies (assessment of the risk-benefit ratio). Once the indication has been made, the patient must be operated on within the first 24 hours to reduce the risk of permanent motor deficit or incomplete clinical recovery.
Le prognosis paralyzing lumbosciatica is generally good, provided they are taken care of as soon as possible. The resumption of socio-professional activities after the treatment is done gradually in a few weeks (sometimes in a few months).
Sequelae (motor deficit) may persist after treatment, which sometimes imposes physiotherapy sessions for the gradual achievement of an improvement in muscle strength.
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