Disc degeneration &prolapse

With normal ageing, the disc becomes dry, the annular fibers

develop fissures &small herniation of the nucleus pulposus

may occur. With time, the disc becomes narrow &osteophytes

appear at the margins of vertebral body. These changes(disc degeneration), common in elderly, are called spondylosis.

If spondylosis is severe →displacement of facet joints →OA

of facet joints with osteophytes that may cause narrowing of

the spinal canal &intervertebral foramen(spinal stenosis).

Note:

* Spondylosis can occur at younger age as a result of

repeated acute disc herniation (prolapse or rupture).

* Spondylosis by itself is usually symptomless but if

severe, there will symptoms of resulting facet joint

osteoarthritis, spinal stenosis & vertebral instability.

Acute disc rupture(prolapse)

The underlying cause is disturbance of hydrophilic properties

of the nucleus pulposus while the direct cause is physical stress.

Pathology:

When rupture occurs → the fibrocartilage material of the

nucleus is extruded posteriorly &the annulus bulges posteriorly

to one side of PLL(posterior longitudinal ligament). If the

rupture is complete, the disc material will lie free in the spinal

canal or intervertebral foramen.

If the rupture is central → compression of the cauda equina.

If the rupture is posterolateral → compression of nerve root

in the intervertebral canal.

Note: Pressure on PLL → backache.

Irritation of nerve root →pain in buttock, thigh &calf(sciatica).

Pressure on the nerve root → sensory loss& motor weakness.

CF → age: 20-45 years; the usual presentation: while lifting he develops severe backache &unable to get up. After 1-2 days, pain

is felt in the buttock & lower limb(sciatica) which ↑with coughing

&straining. Later, there may be numbness or muscle weakness in

the leg &rarely, urine retention(cauda equina compression).

O/E: sciatic scoliosis, back movement are

painful &limited. Tenderness in the midline

with muscle spasm. SLR test is limited & painful.

Neurological examination: motor &sensory loss according to

the level affected →L 4-5 disc prolapse causes pressure on L 5

nerve root resulting in weakness of big toe extension &sensory

loss on outer leg &dorsum of the foot.

L 5- S 1 disc prolapse causes pressure on S1 nerve

root →weak foot plantar flexion &eversion, ↓ ankle

jerk &sensory loss along lateral border of the foot.

Cauda equina compression→ urine retention &

sensory loss over the sacrum.

X-ray (AP &Lat) to exclude bone disease. In chronic

cases→ disc space narrowing with osteophytes.

CT & MRI: confirm the disc protrusion & its level.

ÐḐ: the first attack is easy to Ḑ but with repeated

attacks, the features become atypical but remember:

1- disc prolapse rarely occurs in very young(infection, tumor

or lesthesis) or very old( compression fracture or metastasis).

2- if the patient is ill, think of other serious condition.

3-disc prolapse is episodic, if pain is continuous →tumor or infection.

4- if ˃ 2 neurological levels are affected → neurological disorder.

Note: sciatica is referred pain &can occur in disorder of : facet

joint, sacroiliac joint, ankylosing spondylitis, vertebral infection, vertebral tumor, metastasis & nerve tumor( neurofibroma).

Conservative Ŗ: 2-3 weeks bed rest with pain medications. Other Ŗ may be helpful: physical therapy ± traction, spinal manipulation, epidural steroid injection &weight control. When acute pain

subsides→ spinal corset &back exercise.

Surgical Ŗ→ indications:

1- cauda equina compression.

2- neurological deterioration while under conservative Ŗ.

3- persistent pain( + sciatic tension) after 3 weeks bed rest.

Types of surgery: 1-open laminotomy &discectomy.

2-endoscopic microdiscectomy.

Spondylolisthesis

Forward shift of one vertebra over the one below

carrying with it the superimposed vertebral column.

Site: usually L4-5 or L 5-S1

Note: normal laminae &facets provide locking mechanism

that prevents slipping, if this fail, slipping may occur.

Classification:

1-Dysplastic: congenital defect of the superior sacral facets.

2-Lytic or isthmic (50%): defect in the pars interarticularis (spodylolysis) or the pars become elongated. These lesions

are present at childhood but slipping occurs after several

years due to stress & exercise.

3- Degenerative: disc & facet degeneration.

4- Post-traumatic: fracture of facets, pedicles or pars.

5- Pathological: bone destruction secondary to infection or tumor.

6- Postoperative: wide laminectomy may cause instability &slipping.

Pathology: the commonest is the lytic type in which the pars (between pedicle &lamina) has a gap filled with fibrous tissue, with stress, the fibrous tissue is stretched &the gap increased, so the vertebra becomes 2 parts: anterior part(body, pedicles, transverse processes &superior facet joints) will slip forward leaving the posterior part (laminae, inferior facets &spinous process) behind.

Sometimes, the pars become elongated(no gap) or the facet defected.

Grades: Ι: slipping of 25% of the vertebral body; ΙΙ: slipping

of 50%; ΙΙΙ: slipping of 75%; ΙV: slipping of all the body.

CF: the condition may be symptomless &discovered accidentally.

In children: it is painless but may develop protrusion of the

abdomen due to ↑ lumbar lordosis.

In adults: intermittent backache after exercise or sciatica.

In patient ˃50 years(degenerative Spondylolisthesis): backachsciatica & pseudo claudication of spinal stenosis.

O/E: flat buttock, sacrum pushed upward, transverse lumbar crease, step felt on palpation & neurological deficit may be found.

Investigation: X-ray: AP &Lat. view; Oblique view is best to see

pars defect(decapitated dog); CT &MRI.

Ŗ→ conservative: belt, NSAID, exercise&modification of the job &activities.

Surgical: indication: 1- disabling symptoms;

2-if slip ˃50% &progressing; 3-significant neurological deficit.

Types of surgery:

Anterior fusion(trans- or retro-peritoneal): remove the disc &

insert bone graft with or without posterior instrumentation.

Posterior fusion: fusion of transvers processes + pedicular

screws fixation ± decompression ± interbody fusion.

Prognosis: congenital type→ occur early

&may become severe with neural deficit.

Lytic type→ if slip ˃ 25% → backache later.

Degenerative type: progresses slowly, if the patient

develops spinal stenosis → decompression &fusion.

TB of the spine (Pott's disease)

The spine is the commonest site of skeletal TB &most dangerous.

Pathology:

The TB bacilli are carried via blood &settled in the vertebral body adjacent to the disc through which they spread to another vertebra.

So the usual picture is 2 vertebral bodies &the disc in between are destructed. This leads to sharp angulation called kyphos.

Caseous material may collect in paravertebral soft tissue forming paravertebral abscess. This happens in the thoracic spine,

while in the lumbar spine, the pus will find its way under

iliac fascia to point out in the groin as psoas abscess.

The major risk is pressure on the cord by abscess or displaced

bone or spinal artery thrombosis causing ischemia.

With healing, bony fusion may occur between involved vertebrae. occasionally, reactivation of the disease may occur later on with further collapse &possible risk of cord damage(late onset paraplegia).

CF: usually there is long history of ill health, fever, night

sweating, backache. Occasionally, the patient presents

because of deformity, psoas abscess or paraparesis.

O/E: kyphos can be seen &felt. Cold abscess, if present, is fluctuant & slightly warm but not hot like pyogenic abscess. Spine movements are limited by muscle spasm(+ ve coin's test). Discharging sinus is rare.

Imaging: X-ray: early→ local osteoporosis of 2 vertebrae with narrowing of the disc in between &fuzziness of vertebral endplate.

later→ bone destruction, collapse of the vertebra &spine deformity.

Sometimes, paravertebral fusiform shadow.

With healing→ bony fusion of the vertebrae.

CT & MRI may show cord pressure.

Other test: ↑ESR, + ve tuberculin test.

Needle biopsy: for histo &bacteriological exam.

Differential diagnosis:

1-Pyogenic spondylitis: more acute, toxic

patient , high temperature, ↑WBC , ↑ ASO titer.

2-Scheurmann's disease.

3-Secondary deposit: vertebra may collapse but disc remains intact.

4-Trauma: also cause collapse of vertebra with intact disc.

5- If the patient present with paraplegia, you have to exclude other causes of spinal cord compression.

Ŗ: conservative→ chemotherapy for 6-12 months with or

without bed rest for early &limited disease.

surgery→ for advanced disease &impending or actual severe kyphosis or paraparesis with or without abscess.

Types: costotransversectomy, anterolateral decompression,

anterior radical excision+ bone graft.

The backache problem: 5 patterns

1-transient backache following muscular activity: this suggest simple back strain. It happens more in those with thoracic kyphosis because they compensate by lumbar lordosis. Ŗ→ rest followed by exercise.

2- sudden acute pain &sciatica:

*If the patient ˂20 years → you have to

exclude infection &spondylolisthesis.

*If the patient is between 20-40 years →disc prolapse especially

if has history of lifting, + ve SLR test &neurological deficit.

*if the patient is elderly → osteoporotic compression fracture.

3- Chronic backache with or without sciatica: usually the

patient is ˃40 years having history of disc prolapse some

years ago with recurrent episodes of increasing pain. The

diagnosis is segmental instability &OA of facet joints. X-ray shows spondylosis. Pain ↑ by activity & ↓ by rest. Ŗ→ pain killers, support, local injection, physiotherapy, psychological support &surgical fusion.

4- backache + pseudoclaudication: the patient is ˃50 years with long history of back trouble & now get aching & heaviness with sensory changes in the thigh &leg after walking or standing 5-10 minutes that always relieved by sitting( spine flexion). CT &MRI will diagnose spinal stenosis. Ŗ→ conservative; if fail, decompression & fixation.

5- severe constant localized pain: suggest local bone

pathology like compression fracture, infection or tumor.