Back Pain and Cauda Equina

Question 1

Examples of back pain causes

Answer 1

-Musculoskeletal back pain
-Prolapsed intervertebral disc
-Cauda Equina Syndrome
-Metastatic spinal cord compression
-Spinal stenosis
-Spondylodiscitis

Question 2

General principles of back pain

Answer 2

-Most back pain is innocent and resolves spontaneously
-The history and examination are heavily standardised
-Radiculopathy and myelopathy are different

Question 3

Describe spinal nerves

Answer 3

Mixed nerves
-Motor fibres (efferent to ventral root0
-Sensory fires (afferent to dorsal root)
-Autonomic fibres (efferent to grey and white rami)
31 pairs

Question 4

Describe cervical vertebral anatomy

Answer 4

1. There is an ‘extra’ C8 nerve root (only 7 cervical vertebra)
2. Pedicle / Nerve Root Mismatch
   =The exiting nerve root beneath the pedicle is one number higher i.e. the C7 nerve root is beneath the C6 pedicle
3. Horizontal orientation of exiting nerve roots
   =Together, this means that a prolapsed disc –irrespective of where it prolapses – will only affect the exiting nerve root one level higher i.e. a prolapsed C6/7 IVD will affect the C7 nerve root

Question 5

Describe cauda equina syndrome nerve supply

Answer 5

-Spinal cord ends at L1/2 IVD
-The cauda equina: L2 – S5 (+ coccygeal nerve),descending to their exiting foramen
-Are all mixed spinal nerves, containing:
=Lower motor neurones
=Sensory information
=Autonomic supply to the:
==Bladder (detrusor)
==Anal sphincters
==Urethral sphincters

-Compression of the cauda equina (usually at L4/5) within the vertebral canal due to a massive space occupying lesion:
=Prolapsed IVD is the most common (~70%) (paracentral 90%, lateral or foraminal prolapse 5%)
=Rare: Tumour (~15%), Trauma (~10%), Haematoma, Infection
-Very rare (~1.5– 3 per 1,000,000)
-Surgical emergency to avoid irreversible neurological damage

Question 6

Describe lumbar anatomy

Answer 6

1. Pedicle / Nerve Root match
   =The exiting nerve root beneath the pedicle is the same number i.e. the L4 nerve root is beneath the L4 pedicle
2. Vertical orientation of exiting nerve roots
   =Spinal cord ends at L1/2 and becomes Cauda Equina
   -These means that, at a single spinal level, there is the:
   =Exiting nerve root laterally
   =Traversing nerve root(s) centrally

Question 7

Presentation of cauda equina

Answer 7

-Autonomic dysfunction
-Perianal sensory changes
-Back pain (low), most commonly central disc prolapse at L4/5 or L5/S1
-Leg (typically, but not always, bilateral sciatica 50%)
-Pain +/- Sensory changes (global)
+/- Weakness (global)
-Severe or progressive bilateral neurological deficit of the legs, such as major motor weakness with knee extension, ankle eversion, or foot dorsiflexion.
-Gait disturbance or difficulty walking.
-Saddle anaesthesia/ pins and needles or reduced sensation
+/- urinary incontinence (overflow, not urge), reduced awareness of bladder filling, loss of urge to void
-ED

-Look: Nil
-Feel: Sensory deficit in all distal dermatomes (lower limbs &peri-anal), Palpable, distended bladder

-Move: Motor deficit in all distal myotomes
-PR:
=Diminished peri-anal sensation
=Reduced anal tone
=Diminished anal wink
=Diminished bulbocavernosus reflex

Question 8

Investigation of cauda equina

Answer 8

-Examination: rectal exam
-ASIA chart
-Bladder scan >200mL (N.B.,<200mL has 97% NPV for CES)
-Emergency MRI (within 2 weeks): lumbar spine without IV contrast/ CT

Question 9

Management of cauda equina

Answer 9

-Emergency surgical decompression (microdiscectomy and/or laminectomy)

Question 10

Red flags for neoplasia

Answer 10

> 50 y/o
-History of Ca.
-Pervasive symptoms
-Worsened with straining
-Systemic features of Ca.
-Thoracic pain

Question 11

Red flags for infection

Answer 11

-Fever
-Diabetes / HIV / Immunocompromise
-TB

Question 12

Red flags of fracture

Answer 12

-Trauma
-Structural abnormalities (i.e., ank. spond.)

Question 13

Yellow flags for poor predictors of poor outcome

Answer 13

-Attitudes
-Beliefs
-Compensation
-Use of medical terminology
-Emotions
-Family
-Work

Question 14

Examination of spine/ back

Answer 14

-Look/ feel// move
=Posture
=Colour changes
=Point tenderness
=ROM

-Lower limb neurology
=Tone
=Myotomes
=Reflexes, including clonus and plantars
=Coordination
=Dermatomes

Question 15

Caudal Equina Examination

Answer 15

-External anal sphincter (Pudendal nerve S2-S4)
=Tone (PR)
=Power
=Reflexes - anal wink and bulbavernosus

-Detrusor (Pelvic plexus S1-3)
=Distended bladder
=Incomplete voiding (high PVRV)

-External urethral sphincter (Pudendal nerve S2-4)
=Cannot ‘hold on

Question 16

Investigation in back pain

Answer 16

-Bedside
=Bladder scan -> post-void residual volume >200mL: PVRV <200mL has an NPV of 97%

-Bloods
=Blood cultures – if ?infection
=Blood gases – if unwell
=Routine – FBC, U&E
=Diagnosis-specific – CRP, tumour biomarkers (?myeloma, ?Breast, ?Prostate)

-Imaging
=XR - if ?fracture or ?tumour
=CT - fractures
=MRI: Lumbo-sacral for ?CES, Whole-spine for ?tumour

-Infection
=Fever
=Diabetes / HIV / Immunocompromise
=TB

Question 17

Describe musculoskeletal pain

Answer 17

-2nd most common reason to visit a doctor
-90% resolves spontaneously within 1 year
-Aetiology - by definition, no clear cause. Possibilities include:
=Muscle strain
=Degenerative disc
=Ligamentous injury
=OA of the facet joints

-Risk factors: Obesity, stress, psychiatric co-morbidities, physically demanding jobs

Question 18

Presentation of MSK back pain

Answer 18

-Pain
=Lumbosacral , sharp and intense for 1 to 2 days, muscle spasm, most recover within 3 months
=No radiation below knee
-Stiffness (difficulty bending)
-No red flags

-Look: nil
-Feel: tenderness in paraspinal muscles +/- SI joints in common
-Move: nil specific/ may have restricted range of motion, muscle tenderness or trigger points
-SLR negative

Question 19

Investigation of MSK back pain

Answer 19

-Clinical
-(MRI first line for most, if imaging required)
-(Lumbar XR useful in trauma or if >70 y/o)

Question 20

Management of MSK back pain

Answer 20

-Non-pharmacological is first line
=Reassurance
=Weight loss
=Normal physical activity
=Heat packs
=Group physio
-Pharma: NSAIDs

Question 21

Describe prolapsed IVD

Answer 21

-Protrusion of the nucleus pulposus through the annulus fibrosus
=Pro-inflammatory -> localised pain
=Compression of: The exiting nerve roots (common) -> radiculopathy, The spinal cord (rare) -> myelopathy

-95% are L4/5 or L5/S1 level (N.B., there is no cord at this level!)
-Aetiology: recurrent torsional strain
-Risk factors: male, occupation, increasing age

Question 22

Types of prolapsed IVD

Answer 22

Paracentral prolapse (90%): affect nerve root below
-Compress the traversing nerve root, leading to symptoms affecting the nerve root ‘below’
=i.e. a paracentral L4/5 IVD prolapse will compress the traversing L5 nerve root (+/- S1)

Lateral/ Foraminal prolapse (5%): affect nerve root at same level
-Compressing the exiting nerve root at the same spinal level
=i.e. a lateral L4/5 IVD prolapse will compressing the exiting L4 nerve root

Question 23

Presentation of Prolapsed IVD

Answer 23

-Pain- typically sudden onset
=Low back pain + Referred pain to the relevant dermatome
+/- weakness in relevant myotome
=No red flags
=Leg pain usually worse than back, pain often worse when sitting

-Look: Nil
-Feel: Sensory deficit in relevant dermatome +/- paraspinal muscle tenderness
-Move: Motor deficit in relevant myotome
-SLR positive

Question 24

Investigation of prolapsed IVD

Answer 24

-Clinical
-XR often performed initially
-MRI if symptoms >1 month or red flags

Question 25

Management of Prolapsed IVD

Answer 25

-Conservative is first line – 95% improve within 3/12;5% develop chronic symptoms
=Reassurance
=Weight loss
=Normal physical activity
=Heat packs
=Group physio
=NSAIDs
-Second line: Nerve root corticosteroid injection

NICE recommend using the same drugs as for back pain without sciatica symptoms i.e. first-line is NSAIDs +/- proton pump inhibitors rather than using neuropathic analgesia (e.g. duloxetine)
=if symptoms persist e.g. after 4-6 weeks) then referral for consideration of MRI is appropriate

Question 26

Symptoms and signs of sciatica

Answer 26

-Unilateral leg pain radiating below the knee to the foot or toes.
-Low back pain — if present, which is less severe than any leg pain.
-Numbness, tingling (paraesthesia) in the distribution of a nerve root (dermatome).
-Weakness or reflex changes, or both in a myotomal distribution.
-A positive result in a straight leg raise test — which means with the person lying supine, the hip is flexed gradually with the knee extended. Pain reproduced below 60 degrees of hip flexion on the ipsilateral side indicates a positive test.

Question 27

Assessment of sciatica

Answer 27

-StarT back tool: questionnaire
-Spine: deformity, curvature, tenderness
-Gait, walking, pain behaviour
-Passive and active range of motion: Pain on flexion that radiates to the leg suggests disc herniation with impingement on a nerve root; pain on extension can suggest either facet arthropathy or spinal stenosis.
-Straight leg raise

Question 28

Features of L3 nerve root compression

Answer 28

Sensory loss over anterior thigh
Weak hip flexion, knee extension and hip adduction
Reduced knee reflex
Positive femoral stretch test

Question 29

Features of L4 nerve root compression

Answer 29

Sensory loss anterior aspect of knee and medial malleolus
Weak knee extension and hip adduction
Reduced knee reflex
Positive femoral stretch test

Question 30

Features of L5 nerve root compression

Answer 30

Sensory loss dorsum of foot
Weakness in foot and big toe dorsiflexion
Reflexes intact
Positive sciatic nerve stretch test

Question 31

Features of S1 nerve root compression

Answer 31

Sensory loss posterolateral aspect of leg and lateral aspect of foot
Weakness in plantar flexion of foot
Reduced ankle reflex
Positive sciatic nerve stretch test

Question 32

Presentation of spinal metastases and metastatic spinal cord compression

Answer 32

-Pain:
=Earliest and most common symptom
=Thoracic/cervical (new) or lumbar (worsening)
=Unremitting (not relieved by lying down), nocturnal
=Worse with straining (sneezing, coughing)
=Tenderness
-Leg weakness -> difficulty walking (2/3rds)
-Sensory changes in the lower limbs, numbness
-Autonomic dysfunction: Bladder, Bowel

-Below the affected spinal level:
=UMN deficit
=Sensation: diminished
=Reflexes: initially diminished, then hyperreflexia
=Autonomic: bladder dysfunction (initially flaccid paralysis -> evolves to hypertonic bladder over time)
=Lesions above L1 usually result in upper motor neuron signs in the legs and a sensory level. Lesions below L1 usually cause lower motor neuron signs in the legs and perianal numbness. Tendon reflexes tend to be increased below the level of the lesion and absent at the level of the lesion

Extradural compression accounts for the majority of cases, usually due to vertebral body metastases. It is more common in patients with lung, breast and prostate cancer

Question 33

Cancer red flags

Answer 33

Age over 50 years or under 18 years.
Gradual onset of symptoms or progressive pain.
Severe unremitting pain that remains when the person is supine or at rest, aching night pain that prevents or disturbs sleep, pain aggravated by straining (for example, at stool, or when coughing or sneezing), and thoracic pain.
Mechanical pain (aggravated by standing, sitting or moving).
Localized spinal tenderness.
Claudication (muscle pain or cramping in the legs when walking or exercising).
No symptomatic improvement with therapy.
Unexplained weight loss.
Past history of cancer — breast, lung, gastrointestinal, prostate, renal, and thyroid cancers are more likely to metastasize to the spine.

Question 34

Investigation and management of metastatic spinal cord compression

Answer 34

-MRI: NICE guidelines recommend a whole MRI spine within 24 hours of presentation

-Lie flat and log roll (prevent vertebral collapse)
-Urgent corticosteroid dose (16mgdexamethasone + PPI for gastro protection)
=Unless lymphoma?? NICE
+/- Surgery (decompression and stability)
+/- Radiotherapy

Question 35

Describe spinal stenosis

Answer 35

Lumbar spinal stenosis is a condition in which the central canal is narrowed by tumour, disk prolapse or other similar degenerative changes.

-Due to degenerative disease of the spine:
=Hypertrophy of these degenerative tissues encroaches on the spinal canal and neural foramina, therefore limiting space for the neural tissues.
=Since this occurs preferentially in the lumbar spine, it is predominantly the cauda equina that is affected
=Leads to neurogenic claudication, can cause cauda equina

Question 36

Presentation of spinal stenosis

Answer 36

-Back pain, worsened by activity
-Leg neurogenic claudication during activity:
=Worse downhill, standing
=Better uphill (c.f., this is the reverse of vascular claudication)
=Relieved by leaning forward / sitting (N.B., stopping doesn’t relieve symptoms)
-Leg paraesthesia, with the same aggravating /relieving factors as above
+/- urinary incontinence (overflow, not urge)

-Characteristically featureless examination
-Occasionally diminished ankle reflex (S1/2) and patellar reflex (L3/4)

Question 37

Neurogenic vs vascular claudication

Answer 37

-N
=Postural changes
=Walking upright, standing stationary causes symptoms
=Sitting, stationary bicycle (back flexed) relieves symptoms
=Up stairs easier

-V
=Walking upright, stationary bicycle causes symptoms
=Standing stationary, sitting relieves symptoms
=Down stairs easier
=Abnormal pulses

Question 38

Investigation of spinal stenosis

Answer 38

-MRI gold standard
-XR -> degenerative changes, canal narrowing

-Historically a bicycle test was used as true vascular claudicants could not complete the test.

Question 39

Management of spinal stenosis

Answer 39

-Conservative: weight loss, PT
-Epidural injections
-(Operative if failure to improve): laminectomy

Question 40

Describe spondylodiscitis and risk factors

Answer 40

-Acute bacterial infection of the intervertebral disc
=May spread to the vertebral bodies (osteomyelitis) or the epidural space (epidural abscess)
-S. aureus most common organism

-Risk factors:
=Immunosuppression or immunodeficiency
=DM
=IVDU
=Malnutrition

-Causes
=Bacterial: Staphylococcus aureus is the most common cause of discitis
=Viral
=TB
=Aseptic

Question 41

Clinical features of spondylodiscitis

Answer 41

-Back pain
-Fever, rigors, sepsis
+/- neurological deficit
=e.g. changing lower limb neurology
=if an epidural abscess develops

Question 42

Investigations of spondylodiscitis

Answer 42

-MRI
-Blood culture
-CT-guided biopsy of BC negative

Question 43

Management of spondylodiscitis

Answer 43

-IV Abx 6-8 weeks, identify the organism with a positive culture (e.g. blood culture, or CT-guided biopsy)
+/- surgical debridement

-the patient should be assessed for endocarditis e.g. with transthoracic echo or transesophageal echo. Discitis is usually due to haematogenous seeding of the vertebrae implying that the patient has had a bacteraemia and seeding could have occurred elsewhere

Question 44

Overview of spinal epidural abscess

Answer 44

-A spinal epidural abscess (SEA) is a collection of pus that is superficial to the dura mater (of the meninges) that cover the spinal cord (encapsulated by pyogenic membrane)
-In SEA, bacteria enters the spinal epidural space by contiguous spread from adjacent structures (e.g. discitis), haematogenous spread from concomitant infection (e.g. bacteraemia from IVDU), or by direct infection (e.g. spinal surgery). Immunosuppression is another major risk factor, which may be caused by congenital immune disorders, acquired immune disorders (such as HIV, diabetes or alcoholism or by iatrogenic means (e.g. chemotherapy or steroids).
-Staph aureus

-Patients present with a combination:
fever
back pain
focal neurological deficits according to the segment of the cord affected.

Investigations
Bloods (including inflammatory markers, HIV, Hep B, Hep C, and preoperative blood tests (coagulation and group and screen))
Blood cultures
Infection screen (including chest x-ray and urine culture)*
MRI whole spine (the entire spine is imaged since skip lesions may be present)

*If the primary source of infection is not clear, a wide search for sources requires investigations including echocardiography and dental x-rays.

All patients will require a long-term course of antibiotics which is at first broad spectrum but maybe later refined based on culture results. Patients with large or compressive abscesses, patients with significant or progressive neurological deficits or those who are not responding to antibiotics alone are considered for surgical evacuation of the abscess.

Question 45

Epidemiology of osteoporotic vertebral fractures

Answer 45

Osteoporosis is far more common in females than in males. The male-to-female ratio is 1:6.
25% of women will have developed osteoporosis by the age of 80 .
The prevalence of vertebral osteoporotic fractures is difficult to determine, as not all patients present to a clinician and fractures may not always be clearly identifiable on X-ray

Question 46

Risk factors for osteoporotic vertebral fractures

Answer 46

-Advancing age is a major risk factor osteoporotic fractures: Women ≥ 65 years old and men ≥ 75 years old should be considered for fracture risk assessment. Women in this age bracket are almost certainly post-menopausal, therefore have reduced oestrogen levels - this is a risk factor for osteoporosis.
-Previous history of a fragility fracture
-Frequent or prolonged use of glucocorticoids
-History of falls
-Family history of hip fracture
-Alternative causes of secondary osteoporosis e.g. Cushing’s disease, hyperthyroidism, chronic renal disease
-Low BMI (< 18.5)
-Tobacco smoking
-High alcohol intake: > 14 units/week for women, > 21 units/week for men

Question 47

Presentation of osteoporotic vertebral fractures

Answer 47

-Asymptomatic: an osteoporotic vertebral fracture may be diagnosed through an incidental finding on X-ray
-Acute back pain
-Breathing difficulties: changes in the shape and length of vertebrae lead to the compression of organs such as the lungs, heart and intestine
-Gastrointestinal problems: due to compression of abdominal organs
-Only a minority of patients will have a history of fall/trauma

-Older age.
Major trauma at any age (such as a road traffic collision or fall from a height), mild trauma in people aged over 70 years, prolonged corticosteroid use, history of osteoporosis.
Structural deformity of the spine (such as a step from one vertebra to an adjacent vertebra) may be present.
Contusion or abrasion.
There may be point tenderness over a vertebral body.

Signs:
-Loss of height: vertebral osteoporotic fractures of lead to compression of the spinal vertebrae hence a reduction in overall length of the spine and thus the patient becomes shorter
-Kyphosis (curvature of the spine)
-Localised tenderness on palpation of spinous processes at the fracture site

Question 48

Investigations of osteoporotic vertebral fractures

Answer 48

Investigations:
X-ray of the spine: This should be the first investigation ordered and may show wedging of the vertebra due to compression of the bone. An X-ray of the spine may also show old fractures (which can have a sclerotic appearance)

Other investigations:
CT spine: gives a more detailed view of the bone structure, therefore can visualise the extent/features of the fracture more clearly
MRI spine: Useful for differentiating osteoporotic fractures from those caused by another pathology e.g. a tumour

In order to assess the likelihood of future fractures, risk factors are taken into account and a dual-energy X-ray absorptiometry (DEXA) scan should be considered. DEXA scans essentially assess bone mineral density. According to NICE, the FRAX tool or QFracture tool can be used to estimate the 10-year risk of a fracture. These tools each require the clinician to input patient information into a form and this information is used by the programme to calculate the risk.

Question 49

Diseases affecting the vertebral column

Answer 49

-Ankylosing spondyloarthritis
-Scheuermann’s disease
-Scoliosis
-Spina bifida
-Spondylolysis
-Spondylolisthesis

Question 50

Infection red flags

Answer 50

Fever.
Tuberculosis, or recent urinary tract infection.
Diabetes mellitus.
History of intravenous drug use.
HIV infection, use of immunosuppressants, or the person is otherwise immunocompromised.
Pain at rest.
Raised inflammatory markers.