Lumbar disc herniation
Spinal disorders and the pain associated with them account for a significant portion of disability at work, with most complaints occurring in the lumbar region. Men are more frequently affected. It is essentially a disease of the middle aged, unless precipitated by trauma. L4/5 and L5/S1 disc account for 90% of the cases, with each level affected about equally. L3/4 disc accounts for the majority of the remaining herniations.
In the acute presentation, symptoms often follow trauma or an injury to the disc produced by a sudden spinal strain, such as lifting heavy weights. There is acute low back pain, and, in the event of nerve root compression, radiating pain, paresthesias, and motor weakness. Severe bilateral root dysfunction may produce bowel and bladder incontinence and sexual dysfunction. If the leg pain is not immediately experienced, it usually appears over ensuing hours with associated paresthesias.
The leg pain is usually worse and in dermatomal fashion. The back pain is thought to be secondary to activation of the sinu-vertebral nerves to the annulus, which share a central pathway with the nerve roots.
Chronic form is characterized by chronic intermittent exacerbations of back ache, usually without leg pain initially. The backache usually subsides with rest and conservative measures, only to reoccur. The leg pain may be as well localized as in the acute form.
The pain , unlike the pain due to tumors, is usually subsides to some extent and with recumbency; the pain is aggravated by increased activities, bending forwards, coughing, sneezing, and straining at stools. Prolonged sitting increases the intradiscal pressure and the pain.
On examination, the patient presents with findings of axial pain and radiculopathy.
a) The paraspinal muscles are often in spasm, particularly on the side opposite the leg pain, and are tender to palpation. The patient leans away from the side of leg pain with the hip and knee flexed in an effort to reduce the leg pain.
Spinal movements are restricted due to pain.
Lateral bending towards the side of leg pain closes the intervertebral foramen, compressing the nerve root, and worsens the pain.
The straight leg raising test and the crossed straight leg ( contra lateral leg) raising stretches the sciatic nerve and L5 and S1 root pain get worse.
The reverse straight leg (femoral stretch test) raising stretches the femoral nerve and reproduce the leg pain in the distribution of the affected nerve root contributing to the femoral nerve(L2,3 or 4).
b) Neurological examination may detect the motor, sensory, and reflex impairment (LMN type).
In the lumbar region, the nerve roots exit through the intervertebral foramen caudal to their corresponding vertebral pedicle (e.g.: the L5 root exits at L5/S1 intervertebral foramen); the majority of disc herniations, being posterolateral, compress the root that exits at the intervertebral foramen below the level of the involved disc (L5 root in L4/5/ posterolateral disc herniation). In the less commoner lateral herniation, the root, that exits the foramen at the level of the involved disc, is affected (L5 root in L5/S1 lateral disc herniation).
L5 radiculopathy may present with pain, and paresthesia/numbness along the posterolateral aspect of the leg down to the great toe; weakness of extensor hallusis longus and dorsiflexion may be noted.
S1 radiculopathy may present with pain, and paresthesia/numbness along the posterior aspect of the leg down to the lateral aspect of the heel and foot; weakness of ankle plantar flexion may be detected. Ankle jerk may be absent.
L4 radiculopathy (as in the posterolateral disc herniation at L3/4) may present with pain and paresthesia/numbness along the anterolateral thigh and below the knee to the medial aspect the leg and foot; weakness of quadriceps and knee extension may be noted.
L3 radiculopathy the pain and paresthesia may be localized over the anteromedial thigh and in L2 the distribution is over the groin. Both L2 and L3 radiculopathies may cause quadriceps weakness.
Large central discs may cause bilateral symptoms or cauda equina syndrome. characterized by asymmetric pain and paresthesias in the perineum and down the back or front of the thighs and legs. Sensory disturbances may be limited to the backs of the thighs, buttocks, anus, and perineum, so called saddle anesthesia. paralysis of the bladder and rectum with associated incontinence may occur if the compression is low and affects the sacral roots bilaterally.
MRI is the imaging modality when evaluating the lumbar spine. It enables visualization of the conus and cauda equine and helps to rule out neoplasia and other intradural lesions.
Its multiplanar capabilities make it suitable for visualising far lateral disc herniations as well as the paravertebral structures. It appears to correlate more accurately with surgical findings at a rate of 90% compared with 77% for CT imaging.
CT is a possible alternative for patient unable to undergo MRI, whereas myelography or postmyelographic CT may be more useful in pinpoint stenotic areas
The initial management is non-operative, unless the patient presents with significant neurological deficit.
The medical management traditionally involves bed rest and analgesics and anti-inflammatory drugs. Muscle relaxants help in some. TENS helps in about 20% of patients.
With the exception of a cauda equina syndrome and neurological deficit, surgery should not be considered earlier than 6 weeks from onset of symptoms.
Indications for surgery include failure of acceptable pain control by non-operative measures, progressive neurological deficit, and cauda equina syndrome.
The traditional approach to lumbar discectomy is through posterior hemilaminotomy and foraminotomy, either in prone position or ‘knee-elbow’ position, usually under general anesthesia. Use of a microscope helps and has become a routine these days.
Lately, fenestration (microlumbar discectomy – wherein no bone is removed and the disc is approached by excising the ligament flavum at the required level) is increasingly employed with good results. The advantages in addition to minimal disturbance to spines, are less post operative discomfort and less stay in the hospital.
Whichever approach is used, at least 10gms of disc material has to be removed for adequate pain relief.
Most common intraoperative complications is negative exploration or wrong –level spine surgery.
Then injury to the One of the neural element, dural tear must be avoided. Failure to close the rent produces pseudomeningocele and recurrence of symptoms.
Bacterial discitis .
Life threatening injuries to major vessels e.g.: aorta, vena cava, iliac vessels, bowel perforation has been reported. Very rare complications have been also reported such as blindness, deep vein thrombosis, raised ICP.
Approximately, 2/3 of the patients with acute sciatica recover within 4 weeks; about 1/3 of them report with recurrence. The main advantage of surgery is to accelerate the time to recovery.
Patients with more than 6 months of symptoms have poorer outcome