9: Lumbar Spine & Spinal Conditions Flashcards
what is mechanical back pain
- characterised by pain when the spine is loaded that worsens w exercise and is relieved by rest
- tends to be intermittent and often triggered by innocuous activity
what are risk factors for mechanical back pain
- obesity
- poor posture
- sedentary lifestyle w deconditioning of paraspinal muscles
- poorly designed seating and incorrect manual handling
what are degenerative changes that can take place in the vertebral column
disc degeneration and marginal osteophysis
- nucleus pulposus of the intervertebral discs dehydrate w age which leads to decreased height, bulging of discs and alteration of the load stresses on the joint
- osteophytes called syndesmophytes develop adjacent to end plates of the discs = MO
- increased stress on facet joint = osteoarthritic changes
- facet joints innervated by meningeal branch of spinal nerve so arthritis in these joints perceived as painful
- with this, intervertebral foramina decrease in size –> compression of spinal nerves (radicular/nerve pain)
why does pain occur in ‘slipped disc’
due to herniated disc material pressing on a spinal nerve
what are the four stages of a disc herniation
- disc degeneration: chemical changes associated w ageing –> dehydration and bulging of disc
- prolapse: protrusion of nucleus pulposus (contained within rim of annulus fibrosus) occurs w slight impingement into spinal canal
- extrusion: NP breaks through AF but still contained within disc space
- sequestration: NP separated from main body of disc and enters spinal canal
at which two sites are the nerve roots most vulnerable
- where they cross the intervertebral disc (paracentrally)
- where they exit the spinal canal in the intervertebral foramen (far laterally)
how does the nucleus pulposus most commonly herniate
posterolaterally, causing compression of a spinal nerve root within the intervertebral foramen
- known as a paracentral prolapse and occurs in 96% of cases
- 2% cases = ‘far lateral’ herniation
- 2% = central i.e. directly towards the spinal cord
which nerve is most at risk in ‘far lateral’ disc herniation
exiting nerve root
- this is the nerve root that emerges from the spinal canal at the same level as the intervertebral disc
which nerve is most at risk in a paracentral herniation
traversing nerve root
- so in a paracentral herniation of L4/L5 disc, L5 root = most frequently compressed
what does central herniation carry risk of
cauda equina syndrome
what is sciatica
pain caused by irritation or compression of one or more of the nerve roots that contribute to the sciatic nerve (L4,L5, S1-3)
- if the nerve compression also causes paraesthesia, this will be only experienced in the affected dermatome (rather than the full path from lumbar spine to dermatome)
causes of sciatica (2)
- marginal osteophytosis
- slipped disc
where is sciatica pain typically experienced
back and buttock and radiates to the dermatome supplied by the affected nerve root
pain distribution of L4 sciatica
anterior thigh, anterior knee and medial leg
pain distribution of L5 sciatica
lateral thigh, lateral leg and dorsum of foot
pain distribution of S1 sciatica
posterior thigh, posterior leg, heel and sole of foot
what is cauda equina syndrome and what are its causes
- can develop in context of prolapsed intervertebral disc when there is ‘canal filling disc’ that compresses lumbar and sacral nerve roots within spinal canal
- causes:
- disc prolapse
- primary/secondary tumours affecting vertebral column/meninges
- spinal infection/abscess
- spinal stenosis secondary to arthritis
- vertebral fracture
- spinal haemorrhage
- late stage ankylosing spondylitis (inflamm condition affecting spine)
red flag symptoms of cauda equina syndrome
- bilateral sciatica
- perianal numbness
- painless retention of urine
- incontinence
- erectile dysfunction
how is cauda equina syndrome treated
surgical decompression within 48 hours of the onset of sphincter symptoms or poor prognosis
consequences of missing a diagnosis of cauda equina syndrome
- chronic neuropathic pain
- impotence
- intermittent self-catheterisation
- faecal incontinence
- loss of sensation
- lower limb weakness requiring wheelchair
what is spinal canal stenosis
abnormal narrowing of the spinal canal that compresses either the spinal cord or the nerve roots
causes of spinal canal stenosis
tends to affect elderly and often due to combo of:
- disc bulging
- facet joint OA
- ligamentum flavum hypertrophy
other causes:
- compression fractures of the vertebral bodies
- spondylolisthesis
- trauma
symptoms of spinal canal stenosis
symptoms depends on region of cord or nerve roots that affected w lumbar stenosis being most common, then cervical stenosis
- Discomfort whilst standing (95% of patients)
- Discomfort or pain in the shoulder, arm or hand (for cervical stenosis) or in the lower limb (for lumbar stenosis)
- Bilateral symptoms in approximately 70% of patients
- Numbness at or below the level of the stenosis
- Weakness at or below the level of the stenosis
- Neurogenic claudication
neurogenic claudication
causes, symptoms, treatment
- symptom rather than diagnosis
- pt reports pain and/or pins and needles in legs on prolonged standing and on walking, radiating in a sciatica distribution
- results from compression of spinal nerves as they emerge from lumbosacral spinal cord –> venous engorgement of nerve roots during exercise –> reduced arterial inflow and transient arterial ischaemia
- ischaemia of affected nerve –> pain and/or paraesthesia
- can be present in one or both legs
- clasically relieved by change in position and flexion of the spine
what is spondylolisthesis
anterior displacement of the vertebra above relative to the vertebra below
classifications of spondylolisthesis
- congential/dysplastic: congential instability of the facet joints
- isthmic: defect in pars interarticularis
- degenerative: facet joint arthritis and joint remodelling (>50)
- traumatic: acute fractures in neural arch (no pars interarticularis)
- pathological: infection/malignancy
- iatrogenic: surgical intervention e.g. too much lamina/facet joint excised during laminectomy operation
isthmic type of spondylolisthesis
defect (e.g. stress fracture) develops in the pars interarticularis which is the part of the vertebra between superior and inferior articular processes
- complete fracture w/out displacement = spondylolysis
- once anterior displacement of upper vertebra occurs = spondylolisthesis which may or may not be associated w gross instability of the vertebral column
symptoms and treatment of spondylolisthesis
- some individuals asymptomatic but most complain of discomfort from lower back pain to incapacitating mechanical pain, sciatica from nerve root compression and neurogenic claudication
- treatment: using screws and rods to stabilise the spine
how do you spot spondylolysis
trace outline of ‘scottie dog’ in oblique view of spine
how can you detect grossly-displaces spondylolisthesis
- trace line of anterior and posterior longitudinal ligaments to detect ‘step’ at site of displacement
what is a lumbar puncture
withdrawal of fluid from the subarachnoid space of the lumbar cistern
- important diagnostic test for variety of CNS disorders e.g. meningitis, MS, etc
how is a lumbar puncture performed
- pt lying on side with back and hips flexed i.e. knee to chest
- flexion of vertebral column facilitates insertion of needle by spreading the laminae and spinous processes apart thereby stretching ligamentum flavum
- skin covering lower lumbar vertebrae anaesthetized and LP needle inserted in midline between spinous processed of L3/L4 or L4/L5 vertebrae
- can be located by finding the plane transecting the highest points of the iliac crests—the supracristal plane—this usually passes through the L4 spinous process (no danger of damaging spinal cord here)
- pass needle 4-6cm, which will pop through ligamentum flavum, puncturing dura and arachnoid then enters lumbar cistern
- when stylet removed, CSF escapes then collected
in a LP, state the structures through which the needle will pass from skin to subarachnoid space
- skin
- subcutaneous fat
- ligamentum flavum
- epidural fat and veins
- dura mater
- arachnoid mater
- subarachnoid space
spinal nerves
herpes zoster (shingles)
- viral infec. which almost always affects the skin of a single dermatome
- reactivation of chickenpox (Varicella zoster virus)
- virus travels through cutaneous nerve and remains dormant in dorsal root ganglion after chickenpox
- when host = immunosuppressed, VZV reactivates and travels through peripheral nerve to skin of a single dermatome
what is a motor unit
single motor neuron and the skeletal muscle fibres it innervates
what are the most common sites for ‘slipped discs’
L4/5
L5/S1
- due to mechanical loading at these joints
what is the most common form of spinal infection
infection of vertebral body - spondylitis
what are differentials for spinal infection
- vertebral osteomyelitis
- discitis: isolated infection of the IV disc namely nucleus pulposus; children
- epidural abscess: space between dura mater and vertebral column; 50-70M
- subdural abscess: space between dura and arachnoid
- spinal cord abscess
what are the main risk factors for spinal infections
- IV drug use
- immunosuppression
- malignancy
- DM
- recent spinal surgery
what is the typical presentation of a spinal infection
- back pain which is worse on movement and worse at night
- associated w pyrexia + radicular signs
- O/E: focally tender at level of infection
what investigations are inidicated in spinal infection
- routine bloods: FBC, CRP, U&Es, LFTs + cultures
- imaging: MRI (gold standard) + CT (to show extent of bony involvement)
what investigation is indicated in confirmed cases of spinal infection
CT-guided biopsy to obtain samples for microbiology and histology
- help w abx choice
what is the management of spinal infection
- long term IV abx ~6 weeks for discitis
- immobilisation in significant pain or spinal instability
when is surgical intervention indicated in spinal infections
- evidence of significant bone destruction causing bone instability
- neuro deficits
- poor response to antimicrobial treatment
what are the goals of surgery in spinal infection
- debride infected tissue
- drain residual pus
- restore spinal stability
how is response to treatment monitored in spinal infection
- look at symptoms
- inflamm markers
- repeat MRI
what are red flags of back pain
what are risk factors of spinal tumours
- genetic conditions e.g. neurofibromatosis 1/2, Tuberous sclerosis, Von Hippel-Lindau, Li-Fraumeni
- elevated radiation exposure
- previous malignancies
- FHx
what is the 1st line investigation for a suspected osteoporotic vertebral fracture
X-ray spine
