Mechanical Disorders : Intervetebral Disc Dr Munir Saadeddin

Disorders of Intervertebral Disc Are thought to be the cause of most cases of low back pain Are common at middle age Result from loss of hydration of the Annulus Pulposis or major trauma to disc

Function of Intervertebral Disc It functions as a cushioning structure It is a structure of shock absorption The amount of pressure inside the disc varies according to posture of human Normally it does not encroach on spinal canal posteriorly

Anatomy of Intervertebral Disc

Anatomy of Intervertebral Disc

Fresh Cadaver Specimen of a Disc

Anatomy of Intervertebral disc The disc is a biconvex structur It consists of outer layer of Interlaced fibers called Annulus Fibrosis and central layer called Nucleolus Pulposis The Nucleolus is soft, elastic and well hydrated structure at young age

Pressure inside the Disc Least pressure is when person is lying flat Pressure increases 3 folds on twisting in bed Pressure increases 4 folds when standing

Pressure inside the Disc Pressure increases 6 folds on forward bending Pressure increases 10 folds on bending and lifting This explains the most common cause for rupture of intervertebral disc

Pressure inside the Disc

Circumferential Tear in Annulus

Radial Tears of Disc Radial tears are more serious than circumferential tears Circumferential tears cause deep seated backache but radial tears may lead to bulge in the annulus inside the spinal canal or protrusion of nucleolus inside the canal

Protrusion of Intervertebral Disc Usually it is posterolateral as the posterior longitudinal ligament resist central posterior protrusions Central protrusions are usually small, but large protrusions are more serious as they may cause Cauda Equina Syndrome

Protrusion of Disc

Nerve Root Protrusion by PID Protrusion of Intervertebral disc may compress the nerve root exiting spinal canal at that level and may cause inflammatory change Protrusion at L4-L5 compresses L5 Protrusion at L5-S1 compresses S1

Central Disc Protrusions May compress More than one nerve root It does compress central roots like S2 S3 / S4 This leads to compression of nerve roots to bladder and rectum ( Cauda Equina Syndrome )

Clinical Picture of PID

Clinical Picture of PID A middle age mal May present with LBP and or Sciatica (Though sciatica in Arabic is referred to as painful leg in women ) Sometimes follows clear incident of heavy lifting or back straining Frequently NO history of any cause is present

Clinical Picture of PID May present as : Acute , Recurrent or Chronic In Acute cases patient may report that he felt a tear or a click at his back This may be followed by immediate radiation of pain to leg or not Radiation to leg may appear later

Clinical Picture of PID This is NOT a systemic disease There is NO fever or weight loss PAIN IS MECHANICAL i.e. : it follows some posture which increases the intervertebral disc pressure Constant pain or nocturnal (night) pain is a sinister sign Pain is increased by coughing and relieved by lying in bed

Usually it is the lower back Commonly there is Para vertebral muscle spasm We palpate the level of Iliac Crest = level of L4-L5

Palpation in Back Examination We can palpate the Para Spinal muscles ,tips of spinous processes and the inter spinal ligament We cannot palpate the lamina , the disc or vertebral body

Palpation in Back Examination We start by identifying the level of Iliac Crest This corresponds to L4-L5 Almost 5 cm below is L5-S1 Below on the sides there is a dimple which corresponds to upper S.I. Joint

Palpation in Back examination Lesions at L4-L5 will produce tenderness at L4-L5 level Lesions at L5-S1 will produce tenderness at L5-S1 level We can palpate for tenderness at Sciatic Nerve course as well

Examination of Back Movements: Forward Flexion Forward flexion is 90 degrees or when tips of fingers reach level of malleoli Flexion to level of mid-tibia is 60 degrees Flexion to knees is 45 degrees Flexion to mid-Thigh is 30 degrees

Examination of back movements: Back Extension From straight to 30 degrees Some people can do much more (Gymnastics or people with ligament laxity ) Back extension is reduced or lost in people with acute PID ( It may be even –Minus extension as they may walk with flexed back )

Examination of Back Movements: Lateral Flexion Lateral flexion is 30 degrees to right or left Lateral flexion to the same side of pain is always restricted (except in case of axial disc herniation)

Examination of Back Movements: Rotation May be done in EITHER standing or sitting positions In standing position examiner has to immobilise the pelvis of the patient to make sure than there is no rotation of whole body In sitting position body weight immobilises the pelvis and probably more accurate

Walking on Heels = L5 Asking the patient to stand and walk on his heels elicit if there is any weakness at L5 (which is main nerve root for All 3 muscles of dorsiflexion = Tibialis Anterior , Extensor Digitorum and Extensor Hallucis Longus)

Walking on Tip Toes = S1 Asking the patient to stand and walk on tip toes elicit if there is any weakness of S1 (which is the main nerve root for muscles of plantar flexion = Gastocnemius and Soleus

Examination in Supine position Once we ask patient to lie down in bed we start examining certain tests This does NOT include inspection of the back Most important is SLR test ( Straight Leg Raising Test ) and Neurological assessment for the condition

Straight Leg Raising Test

SLR Test It is a Sciatic Nerve Stretch Test Normally it is Painless Is done in supine position Normal from 0-90 degrees Reliable test is between 30-80

Lasague Maneuver

Lasague Maneuver Lasague Maneuver is a modified SLR test It has 3 advantages It is a confirmatory test for SLR It excludes hip or knee pain as a cause for the pain on SLR It excludes malingering patients

Lesions of L3-4 and L4-5

Lesions of L4-5 and L5-S1

Investigations of Backache : x rays Plain X Rays are useful AP, Lateral and Oblique may be done On this lateral view there is obvious sign = Loss of normal lordosis =straitening of lumbar spine

Investigations of Backache : x rays Lateral view or cone view demonstrate narrowed disc space Also this view demonstrates gas shadow in disc space= chronicity= Knott’s sign = vacuum phenomenon

Myelography and radiculography Used to be the most important test for eliciting disc protrusions NOT used these days for the above diagnosis Still used for investigating certain intra spinal and instability conditions

C.T. Scan Disc Protrusion

C.T. Myelography

MRI L4-5 PID

MRI : P I D

MRI : PID=LDH

MRI : PID = LDH

Management of PID Essentially conservative Almost 85% respond to conservative treatment Up to 15% surgical treatment is indicated Severity of symptoms does not indicate severity of disease

Conservative Treatment Should be tried initially in most cases Short period of Bed Rest (< 1 week ) should be tried in ACUTE cases Bed rest is NOT indicated in chronic cases NSAID’s and muscle relaxants are used ( Drugs to protect against G.I. effects especially in the elderly ) Avoids narcotics

Physiotherapy and Exercises Are the most important tools in management Always should be part of treatment Weight reduction and back care education Heat therapy especially Short Wave diathermy and Ultrasound important types of treatments Exercises to strengthen back and abdominal muscles should be done

Chiropractic Therapy & Acupuncture Recently gaining popularity Chiropractics means re-alignment of bones and joints to normal structure (However once we understand the pathology of PID, it is difficult to see how can a disc be put back in place!) Acupuncture is by stimulating specific points by needles and is helpful in some patients

Steroid Injections In PID In selected cases they are valuable adjuvant to other modalities of treatment They are injected in the Extradural space by lumbar or caudal route It is believed they work by reducing the inflammatory changes in the nerve root associated with PID

Surgery in PID Radiological evidence MUST be obtained prior to surgery Theses radiological changes MUST correspond with the clinical picture We have to remember that NOT every bulging disc should be operated on MRI is the golden standard in diagnosis

Indications for Surgery for PID There are Five indications Only one definite and urgent indication in CAUDA EQUINA syndrome Three valid and correct indications (will be explained soon ) One controversial and personal indication

Valid Indications for Surgery in PID Failure of conservative treatment ( for at least 6 weeks ) and continuation of pain Progression of neurological deficit (but initial deficit is not an absolute indication ) Recurrent and disturbing attacks

Controversial indications in PID Time Factor : Patient is not prepared to complete a full period of conservative treatment ( 6 weeks ) to see if it will succeed Patient’s preference Surgeon’s preference

Exclude a psychological causes

Operative procedures for PID At least 15% of cases of PID end up having surgery At USA : at least 250 000 cases are operated on annually At USA : there are 7 million individuals who had back surgery Still at USA : there are 21 million people with disability certificate due to backache !

Aim of surgery for PID To relieve patient of his pain Leg pain can be relieved by removing pressure on nerve root ( Decompression of nerve root ) This is done by removing the bulged or protruded part of the disc and any other part which can be curetted out Back pain can be relieved by stabilising that intervertebral disc segment

Position for surgery for PID

Position for surgery for PID Usually it is Chest-Knee position This is to avoid any pressure on abdomen Avoidance of pressure on abdomen reduces intra abdominal pressure and consequently reduces intra spinal pressure = reduction of venous bleeding from dural veins

Open Disc Surgery 3-5 cm for each disc level Lamina above and lamina below are exposed with the part of Ligamentum Flavum between Part of Ligamentum Flavum and lamina is removed to get access to spinal canal

Open Disc Surgery

Exposure of Dura and Nerve Root

Excision of protruded PID Dura is retracted with the nerve root to expose the protruded PID Once protrusion is exposed it is incised in 5x5 mm cruciate incision Occasionally nucleolus is already penetrated through the annuulus

Excision of PID Protruded or extruded disc is removed and disc space curetted Nerve root should be Free from any compression and Free from tension If any bone was involved it should be removed

Endoscopic Micro- Discectomy Relatively New method of Disc Surgery Minimally traumatic in experienced hands Minimal scar and blood loss Requires high quality surgical tools Fluoroscopy pre and during surgery is necessary Nerve root injury may be as high or even higher than with other methods

Endoscopic Micro- Discectomy

Endoscopic Micro- Discectomy

Percutaneous Discectomy Is done through a cannula inserted lateral to midline into disc space under G.A. or L.A. and nucleolus is sucked with shaver Initially was thought to be easy and simple Has not proved to be very successful Reported success rate is 70% Patient and surgeon are exposed to repeated radiation

Percutaneous Discectomy

Laser Discectomy May become the golden standard for managing PID in the future ( especially when open MRI machines are available ) Route of entry is similar to Percutaneous Discectomy Can be done under local or general anesthesia Not perfect at present