High Yield Overview

LUMBAR RADICULOPATHY

Nerve Root Compression | Dermatomal Patterns | Disc Herniation

L5Most common root

90%Improve conservatively

6-12wksConservative trial

85-95%Microdiscectomy success

ROOT LEVEL PATTERNS

L4 Root

PatternL3-L4 disc, knee extension weakness

TreatmentQuad weakness, reduced knee jerk

L5 Root

PatternL4-L5 disc, EHL weakness

TreatmentMost common, no reliable reflex

S1 Root

PatternL5-S1 disc, plantarflexion weakness

TreatmentAbsent ankle jerk

Critical Must-Knows

L5 root = EHL weakness (big toe dorsiflexion), L4-L5 disc most common
S1 root = Ankle reflex ABSENT, calf weakness (heel walk), L5-S1 disc
L4 root = Knee jerk reduced, quad weakness, anterior thigh numbness
Conservative first: 6-12 weeks for most cases (90% improve)
Cauda Equina: Saddle anesthesia + urinary retention = EMERGENCY surgery

Examiner's Pearls

"
L5 root has NO reliable reflex - motor testing (EHL) is key
"
Leg pain WORSE than back pain distinguishes radiculopathy from axial LBP
"
SLR positive at 30-70° raises intrathecal pressure, reproduces leg pain
"
Crossed SLR (positive in contralateral leg) = high specificity for disc herniation

Clinical Imaging

Imaging Gallery

Axial T2 MRI showing lumbar spine cross-section at L4-L5 level with anatomical labels clearly marking the disc and L5 nerve root - demonstrates spatial relationship between disc and nerve — Axial T2 MRI showing lumbar spine cross-section at L4-L5 level with anatomical labels clearly marking the disc and L5 nerve root - demonstrates spatiaCredit: Ukaigwe A et al. via J Community Hosp Intern Med Perspect via Open-i (NIH) (Open Access (CC BY))

Four-panel MRI series (sagittal, axial, coronal views) showing lumbar facet synovial cyst in 82-year-old woman with radiculopathy and neurogenic claudication - demonstrates alternative cause of nerve — Four-panel MRI series (sagittal, axial, coronal views) showing lumbar facet synovial cyst in 82-year-old woman with radiculopathy and neurogenic claudCredit: Neto N et al. via Insights Imaging via Open-i (NIH) (Open Access (CC BY))

Sagittal T2 MRI with disc height measurements showing degenerative changes and disc height loss - demonstrates foraminal stenosis mechanism from chronic degeneration — Sagittal T2 MRI with disc height measurements showing degenerative changes and disc height loss - demonstrates foraminal stenosis mechanism from chronCredit: Ukaigwe A et al. via J Community Hosp Intern Med Perspect via Open-i (NIH) (Open Access (CC BY))

Critical Lumbar Radiculopathy Exam Points

Cauda Equina Syndrome

SURGICAL EMERGENCY: Saddle anesthesia, urinary retention, fecal incontinence, bilateral leg weakness. MRI + surgery within 24-48 hours. Delayed surgery = permanent bowel/bladder dysfunction.

L5 vs S1 Root

L5: EHL weakness (can't lift big toe), dorsum foot numbness, NO reliable reflex. S1: Calf weakness (can't heel raise), absent ankle jerk, lateral foot/sole numbness.

Conservative Trial

6-12 weeks of conservative treatment for most radiculopathy. 90% improve. Exceptions: Cauda equina syndrome, progressive neurological deficit, intractable pain requiring IV analgesia.

Microdiscectomy

Gold standard surgical treatment for disc herniation. 85-95% success. Faster recovery than conservative but similar long-term outcomes (SPORT trial). 5-10% reherniation rate.

Lumbar Root Patterns - Motor, Sensory, Reflex

Root	Disc Level	Motor Weakness	Sensory Distribution	Reflex
L3	L2-L3	Hip flexion, knee extension	Anterior thigh	None reliable
L4	L3-L4	Tibialis anterior, Quadriceps	Medial leg, medial foot	Knee jerk (reduced)
L5	L4-L5	EHL, Hip abduction, Tibialis posterior	Lateral leg, dorsum foot, 1st web space	None reliable
S1	L5-S1	Gastrocnemius, Peroneals, Gluteus maximus	Lateral foot, sole, posterior calf	Ankle jerk (ABSENT)

Mnemonic

L5 vs S1 Radiculopathy

Lift Big Toe

EHL weakness - can't dorsiflex big toe

Standing on Tiptoes

Calf weakness + absent ankle jerk

Memory Hook:L5 Lifts toe up, S1 Stands on tiptoe down

Mnemonic

SLR - Straight Leg Raise Test

Sensitivity 90%

Good screening test

Low specificity (26%)

Positive in many conditions

Radicular if 30-70°

Positive range for disc pathology

Memory Hook:SLR is Sensitive but Low in Reliability for specificity

Mnemonic

CAUDA - Emergency Signs

Continence (loss)

Bowel and bladder dysfunction

Anesthesia (saddle)

Perineal numbness

Urgent surgery

Within 24-48 hours

Deficit bilateral

Lower limb weakness both sides

Acute retention

Urinary retention (overflow incontinence)

Memory Hook:CAUDA equina needs CAUDA assessment

Overview and Epidemiology

Lumbar Radiculopathy is a clinical syndrome caused by compression or irritation of a lumbar nerve root, resulting in pain, sensory changes, and/or motor weakness in the distribution of that nerve root.

Definition:

The term "sciatica" refers specifically to radicular pain along the sciatic nerve distribution (L4-S3), typically affecting the buttock and posterior/lateral leg. True radiculopathy includes neurological deficit (weakness, numbness, reflex changes) in addition to pain.

Epidemiology:

Factor	Details
Prevalence	5-10% of patients with low back pain
Peak age	30-50 years (disc degeneration begins)
Gender	Slight male predominance (1.5:1)
Most common root	L5 (from L4-L5 disc)
Second most common	S1 (from L5-S1 disc)
Bilateral involvement	Rare - consider cauda equina or central disc

Natural History:

The majority of disc herniations causing radiculopathy will improve without surgery. This forms the basis for conservative management in most cases.

Anatomy and Biomechanics

Lumbar Nerve Root Anatomy

Nerve Root Numbering:

In the lumbar spine, nerve roots exit BELOW the correspondingly numbered pedicle. The L4 root exits below the L4 pedicle, between L4 and L5.

Disc Level	Exiting Root	Traversing Root
L3-L4	L3	L4
L4-L5	L4	L5
L5-S1	L5	S1

Posterolateral vs Central Herniation:

Most disc herniations are posterolateral, compressing the TRAVERSING root (the root that continues down to exit below the next level).

Herniation Type	Root Affected	Example
Posterolateral	Traversing root	L4-L5 PL herniation → L5 root
Far lateral (foraminal)	Exiting root	L4-L5 FL herniation → L4 root
Central	Cauda equina	Large central L4-L5 → multiple roots

Dermatomal Patterns

L4 Dermatome:

Anterior thigh
Medial leg to medial malleolus
Medial foot

L5 Dermatome:

Lateral leg
Dorsum of foot
First web space (pathognomonic)
Great toe

S1 Dermatome:

Posterior calf
Lateral foot
Sole of foot
Small toe

Pathophysiology

Mechanisms of Nerve Root Compression

Mechanical Compression:

The most common cause is disc herniation, where the nucleus pulposus protrudes through a tear in the annulus fibrosus. The disc material directly compresses the nerve root against the bony canal.

Disc Terminology	Description
Bulge	Symmetric, circumferential extension
Protrusion	Focal, base wider than apex
Extrusion	Apex wider than base, through annulus
Sequestration	Free fragment, separated from disc

Chemical Inflammation:

The nucleus pulposus contains inflammatory mediators (phospholipase A2, TNF-alpha) that cause local inflammation and sensitization of the nerve root. This explains why some small herniations cause severe symptoms while large herniations may be asymptomatic.

Other Causes of Radiculopathy

Most Common Cause (90%)

Mechanism: Nucleus pulposus herniates through annular tear, compressing nerve root mechanically and chemically.

Risk Factors: Repetitive flexion-rotation loading, heavy lifting, vibration exposure (truck drivers), smoking (disc nutrition), genetic factors.

Age Pattern: Peak in 30-50 years when disc is still hydrated enough to herniate. Older patients more likely to have stenosis.

Pain Physiology

Nerve Root Pain Characteristics:

Radicular pain differs from referred pain. Radicular pain follows a dermatomal distribution and is often described as sharp, shooting, or electric. Referred pain is duller, more diffuse, and doesn't follow nerve root patterns.

Sensitization:

Chronic compression leads to nerve root sensitization, with lowered thresholds for pain signaling. This explains why minor movements can trigger severe radicular symptoms.

Classification

By Root Level

L3-L4 Disc Herniation

Motor: Knee extension (quadriceps) weakness. Difficulty rising from chair or climbing stairs.

Sensory: Anterior thigh and medial leg to medial malleolus.

Reflex: Reduced or absent knee jerk (L3-L4 reflex arc).

Clinical Tip: Less common than L5/S1. Consider femoral nerve palsy in differential. Femoral stretch test (reverse SLR) may be positive.

By Herniation Type

Type	Location	Root Affected	Clinical Features
Posterolateral	Lateral recess	Traversing root	Classic radiculopathy, SLR positive
Foraminal	Neural foramen	Exiting root	One level up, may be missed on MRI
Central	Central canal	Multiple roots	Bilateral symptoms, cauda equina risk
Extraforaminal	Far lateral	Exiting root	Femoral stretch test may be positive

Severity Grading

Motor Weakness Grading (MRC Scale):

Grade	Description	Clinical Implication
5	Normal power	No motor deficit
4	Movement against resistance	Mild weakness - conservative
3	Movement against gravity only	Moderate weakness - consider surgery
2	Movement with gravity eliminated	Severe weakness - surgery recommended
1	Flicker of contraction	Near complete deficit - urgent surgery
0	No contraction	Complete deficit - emergency surgery

Clinical Presentation

History

Pain Characteristics:

Feature	Radiculopathy Pattern
Location	Leg > back (key feature)
Character	Sharp, shooting, electric
Distribution	Dermatomal (follows nerve root)
Aggravating	Sitting, coughing, straining, forward flexion
Relieving	Standing, lying, walking (unlike stenosis)

Red Flags (Cauda Equina Syndrome):

Cauda Equina Syndrome - Emergency

Any combination of: saddle anesthesia, urinary retention or incontinence, fecal incontinence, bilateral leg weakness, sexual dysfunction. Requires URGENT MRI and surgical decompression within 24-48 hours.

Duration and Progression:

Acute onset suggests disc herniation
Gradual onset may indicate stenosis
Progressive weakness is concerning
Bilateral symptoms suggest central pathology

Physical Examination

Observation:

Antalgic gait
List away from painful side (sciatic scoliosis)
Limited lumbar flexion

Palpation:

Paravertebral muscle spasm
Sciatic notch tenderness

Neurological Examination:

Test	L4	L5	S1
Motor	Knee extension	EHL, hip abduction	Plantar flexion, hip extension
Reflex	Knee jerk	None reliable	Ankle jerk
Sensory	Medial leg/foot	Lateral leg, dorsum foot	Lateral foot, sole

Special Tests:

Test	Technique	Positive Finding	Sensitivity/Specificity
SLR	Raise straight leg, hip flexed, knee extended	Pain 30-70° in radicular distribution	90% sensitive, 26% specific
Crossed SLR	SLR reproduces pain in opposite leg	Pain in contralateral leg	Low sensitivity, HIGH specificity (90%)
Femoral stretch	Prone, extend hip with knee flexed	Pain in anterior thigh	Positive for L4, L3 radiculopathy
Slump test	Seated, chin to chest, extend knee	Reproduces radicular pain	Tension test for dura

Crossed SLR

If raising the UNAFFECTED leg reproduces pain in the AFFECTED leg, this has 90% specificity for disc herniation. It indicates a large disc that is tenting the dura.

Investigations

Imaging Protocol

MRI (Gold Standard):

Sequence	What It Shows
T2 sagittal	Disc degeneration (dark disc), herniations, spinal alignment
T2 axial	Nerve root compression, lateral recess stenosis
T1	Anatomy, fat in foramen (should be bright), bone marrow
STIR	Bone marrow edema, infection, tumor

When to Image:

Standard recommendation is to wait 6 weeks before MRI if no red flags, as many herniations resolve spontaneously.

Indications for Early MRI:

Cauda equina syndrome (URGENT)
Progressive neurological deficit
Suspected tumor or infection
Severe, unremitting pain
Prior malignancy

CT Myelography:

Alternative when MRI contraindicated (pacemaker, severe claustrophobia). Shows contrast around nerve roots but less soft tissue detail.

Electrodiagnostic Studies

EMG/NCS:

Finding	Interpretation
Denervation changes	Positive waves, fibrillations at 3+ weeks
Reduced recruitment	Chronic nerve injury
Normal study	Does NOT rule out radiculopathy (may be too early)

Indications:

Unclear clinical picture
Differentiating radiculopathy from peripheral neuropathy
Medicolegal documentation
Pre-operative confirmation

Diagnostic Injections

Selective Nerve Root Block:

Can be diagnostic if unclear which root is symptomatic. Relief with block confirms that specific root as pain generator.

Epidural Steroid Injection:

More therapeutic than diagnostic. May provide short-term relief and help avoid surgery.

Imaging Gallery

Anatomical Relationships and Pathophysiology

Axial MRI with labeled anatomy showing L4-L5 disc and L5 nerve root relationship — Axial T2-weighted MRI at the L4-L5 level with clear anatomical labels demonstrating the spatial relationship between the intervertebral disc and the L5 nerve root. The image shows how the disc (labeled 'Disc L4-L5') lies in proximity to the nerve root (labeled 'Nerve L5'), illustrating the mechanism by which posterolateral disc herniations compress the traversing nerve root. Key concept: At the L4-L5 level, a posterolateral disc herniation compresses the L5 nerve root (which exits at the L5-S1 foramen below). This labeled cross-sectional view is essential for understanding the disc-nerve relationship and why L4-L5 disc herniation causes L5 radiculopathy (EHL weakness, dorsum foot numbness, no reliable reflex). The L4-L5 level is the most common site of disc herniation (40-50% of cases), making L5 the most commonly affected nerve root.Credit: Ukaigwe A et al. via J Community Hosp Intern Med Perspect via Open-i (NIH) (Open Access (CC BY))

Four-panel MRI series showing lumbar synovial cyst causing radiculopathy — Four-panel MRI series demonstrating an important alternative cause of lumbar radiculopathy: lumbar facet synovial cyst in an 82-year-old woman with left lumbar radiculopathy and neurogenic claudication. Panel A: Sagittal T2 MRI showing hyperintense (bright) cystic lesion arising from facet joint. Panel B: Axial MRI showing cyst compressing thecal sac and nerve root in cross-section. Panel C: Coronal MRI demonstrating cyst relationship to surrounding structures. Panel D: Additional sequence characterizing cystic pathology. Key concepts: (1) **Synovial cysts** arise from degenerated facet joints filled with synovial fluid - common in elderly with facet arthropathy; (2) **Compression mechanism** - cyst extends into spinal canal/lateral recess compressing nerve roots just like disc herniation; (3) **Differential diagnosis** - radiculopathy is NOT always from disc herniation - any mass (cyst, tumor, hematoma) compressing nerve root can cause identical symptoms; (4) **Treatment implications** - requires cyst excision rather than discectomy. This case illustrates the principle that clinical diagnosis of radiculopathy is based on symptoms/exam, while imaging determines the CAUSE of nerve compression.Credit: Neto N et al. via Insights Imaging via Open-i (NIH) (Open Access (CC BY))

Sagittal MRI with disc height measurements showing degenerative changes — Sagittal T2-weighted MRI of lumbar spine with quantitative disc height measurements (14.8mm and 28.5mm at different levels) demonstrating the role of chronic disc degeneration in radiculopathy. The imaging shows multiple intervertebral discs with varying degrees of degeneration: dark discs on T2 imaging indicate desiccation (loss of water content), and decreased disc height at degenerated levels compared to normal levels. Key pathophysiological concepts: (1) **Disc height loss** - degeneration causes disc collapse, reducing neural foraminal height and potentially compressing the exiting nerve root (different mechanism than posterolateral herniation which compresses traversing root); (2) **Foraminal stenosis** - vertical dimension of foramen decreases with disc collapse, narrowing the exit pathway for the nerve root; (3) **Degenerative cascade** - disc collapse leads to facet joint overload, osteophyte formation, ligamentum flavum hypertrophy, and progressive stenosis; (4) **Quantitative assessment** - measurements provide objective documentation of degeneration severity. This illustrates that radiculopathy can result from CHRONIC degenerative foraminal narrowing, not just ACUTE disc herniation.Credit: Ukaigwe A et al. via J Community Hosp Intern Med Perspect via Open-i (NIH) (Open Access (CC BY))

Management

Treatment Algorithm

Conservative Management (First Line):

Intervention	Evidence	Details
Activity modification	Strong	Avoid aggravating activities, NOT bed rest
NSAIDs	Strong	First-line pharmacotherapy
Oral steroids	Moderate	Short course (6 days) may help acute phase
Physical therapy	Strong	Core strengthening, McKenzie extension
Epidural steroid injection	Moderate	50% avoid surgery at 1 year (Riew)

Duration: 6-12 weeks trial before surgery unless red flags present.

Indications for Surgery:

Indication	Timing
Cauda equina syndrome	URGENT (24-48 hours)
Progressive motor deficit	Early (within days)
Severe weakness (MRC ≤3)	Early consideration
Failed conservative (6-12 weeks)	Elective
Intractable pain	Elective

Surgical Management

Gold Standard for Disc Herniation

Technique: Small incision, limited laminotomy/flavectomy, remove herniated disc fragment, preserve as much normal disc as possible.

Outcomes: 85-95% leg pain relief. SPORT trial showed faster recovery than conservative but similar long-term outcomes.

Complications: Dural tear (1-7%), recurrent herniation (5-10%), wrong level (rare but serious), infection (1-2%).

Reherniation: Higher risk with larger annular defect, younger age, male sex, smoking.

SPORT Trial Key Points

Spine Patient Outcomes Research Trial (SPORT): Surgery provided faster relief than conservative care for disc herniation, but long-term outcomes (4 years) were similar. Surgery is NOT mandatory - it accelerates recovery.

Complications

Complications of Conservative Management

Delayed Recovery:

Prolonged disability if not appropriately managed
Chronic pain syndrome development
Muscle atrophy from disuse
Psychological impact (depression, anxiety)

Missed Cauda Equina:

Progressive neurological deficit if cauda equina not recognized
Permanent bladder/bowel dysfunction

Surgical Complications

Intraoperative:

Complication	Incidence	Prevention/Management
Dural tear	1-7%	Careful technique, primary repair, fibrin glue
Wrong level	0.1-0.3%	Intraoperative imaging, confirm with X-ray
Nerve root injury	0.1-0.5%	Adequate visualization, gentle retraction
Vascular injury	Very rare	Avoid plunging instruments anteriorly

Postoperative:

Complication	Incidence	Management
Recurrent herniation	5-10%	May require revision surgery
Infection	1-2%	Antibiotics, possible washout
Epidural hematoma	Rare	Urgent decompression if symptomatic
Chronic pain (FBSS)	10-40%	Multidisciplinary management

Long-Term Complications

Recurrent Disc Herniation:

5-10% at same level
Risk factors: Large annular defect, male, smoking, young age, heavy lifting
Treatment: Revision discectomy or fusion if recurrent

Failed Back Surgery Syndrome (FBSS):

Persistent pain after lumbar spine surgery
Causes: Wrong diagnosis, incomplete decompression, new pathology, scar tissue
Management: Spinal cord stimulation, multidisciplinary pain program

Adjacent Segment Disease:

Rare after discectomy alone
More common after fusion

Evidence Base

SPORT Trial - Disc Herniation

Level I

Weinstein JN et al • JAMA 2006 (2006)

Key Findings:

Randomized trial: surgery vs conservative for lumbar disc herniation
Surgery provided faster pain relief and functional recovery
At 4 years, outcomes converged between groups
Both groups improved substantially from baseline

Clinical Implication: Surgery accelerates recovery but is not mandatory. Conservative care is reasonable first-line treatment for most cases.

Weber Disc Surgery RCT

Level I

Weber H • Spine 1983 (1983)

Key Findings:

Landmark randomized trial of disc surgery
Surgery better at 1 year
Equal outcomes at 4 and 10 years
Natural history generally favorable

Clinical Implication: Long-term outcomes are similar regardless of treatment, supporting conservative management first.

Epidural Steroid Injections

Level I

Riew KD et al • Spine 2000 (2000)

Key Findings:

Transforaminal epidural steroid injections for radiculopathy
50% of patients scheduled for surgery avoided it at 1 year
Significant short-term pain relief

Clinical Implication: ESI can delay or avoid surgery in approximately half of patients with radiculopathy.

Cauda Equina Timing

Level III

Ahn UM et al • Spine 2000 (2000)

Key Findings:

Meta-analysis of cauda equina decompression timing
Surgery within 48 hours associated with better bladder outcomes
Incomplete cauda equina has better prognosis than complete

Clinical Implication: Cauda equina requires urgent decompression within 24-48 hours for optimal neurological recovery.

Viva Scenarios

Practice these scenarios to excel in your viva examination

VIVA SCENARIOStandard

Classic L5 Radiculopathy

EXAMINER

"A 38-year-old male presents with 6 weeks of right leg pain radiating to the dorsum of the foot. He has weakness lifting his big toe. MRI shows L4-L5 right posterolateral disc herniation."

EXCEPTIONAL ANSWER

This is L5 radiculopathy from an L4-L5 disc herniation. Key finding is EHL weakness which localizes to L5. Initial management is conservative: activity modification, NSAIDs, physical therapy. I would discuss epidural steroid injection if not improving. As there are no red flags (cauda equina, progressive deficit) and duration is less than 12 weeks, I would continue conservative management. If symptoms persist beyond 12 weeks or weakness progresses, I would offer microdiscectomy which has 85-95% success for leg pain relief.

KEY POINTS TO SCORE

EHL weakness = L5 root

L4-L5 disc affects traversing L5 root (posterolateral herniation)

Conservative treatment 6-12 weeks first

Microdiscectomy for failed conservative or progressive deficit

COMMON TRAPS

✗Operating immediately for motor weakness without conservative trial

✗Confusing L4 vs L5 radiculopathy

✗Not checking for cauda equina features

LIKELY FOLLOW-UPS

"What is the success rate of microdiscectomy?"

"What are the complications of microdiscectomy?"

"How would you manage a recurrent herniation?"

VIVA SCENARIOStandard

Cauda Equina Syndrome

EXAMINER

"The same patient now presents to emergency with bilateral leg weakness, difficulty voiding, and numbness around the perineum."

EXCEPTIONAL ANSWER

This is cauda equina syndrome - a surgical emergency. Key features are bilateral symptoms, urinary retention, and saddle anesthesia. I would perform a brief focused examination, insert a catheter to measure post-void residual (PVR greater than 100ml is concerning), and obtain an urgent MRI. If confirmed (usually massive central disc), I would proceed to urgent surgical decompression within 24 hours. I would perform a laminectomy and discectomy to decompress the cauda equina. I would counsel the patient that bladder function recovery depends on timing of surgery - earlier decompression has better outcomes.

KEY POINTS TO SCORE

Saddle anesthesia + urinary retention = emergency

Urgent MRI and surgery within 24-48 hours

Check post-void residual (PVR)

Bladder recovery depends on timing

COMMON TRAPS

✗Delaying MRI or surgery

✗Not inserting catheter to check PVR

✗Missing incomplete cauda equina (subtle early signs)

LIKELY FOLLOW-UPS

"What is the difference between incomplete and complete cauda equina?"

"What is the prognosis for bladder function?"

"How would you counsel the patient?"

VIVA SCENARIOStandard

S1 Radiculopathy with Absent Reflex

EXAMINER

"A 45-year-old female presents with 8 weeks of left posterior calf pain and numbness on the sole of her foot. Ankle jerk is absent on the left. SLR is positive at 45 degrees."

EXCEPTIONAL ANSWER

This is S1 radiculopathy, likely from an L5-S1 disc herniation. The absent ankle jerk is pathognomonic for S1 root involvement. The posterior calf and sole distribution confirm S1 dermatome. I would confirm with MRI. Given 8 weeks of symptoms without red flags, I would continue conservative management for up to 12 weeks total. I would offer epidural steroid injection if not improving. If she fails 12 weeks of conservative care, I would offer microdiscectomy. I would counsel that 90% of patients improve without surgery.

KEY POINTS TO SCORE

Absent ankle jerk = S1 root

L5-S1 disc affects S1 root

Positive SLR at 45 degrees supports disc

Conservative management for 6-12 weeks

COMMON TRAPS

✗Confusing S1 with L5 (L5 has no reliable reflex)

✗Not testing single heel raise for motor assessment

✗Rushing to surgery

LIKELY FOLLOW-UPS

"How would you test S1 motor function?"

"What is the natural history of disc herniation?"

"What are risk factors for recurrent herniation?"

VIVA SCENARIOStandard

Far Lateral Disc Herniation

EXAMINER

"A 52-year-old male has 4 weeks of anterior thigh pain and weakness climbing stairs. SLR is negative, but femoral stretch test is positive. MRI shows L3-L4 far lateral disc herniation."

EXCEPTIONAL ANSWER

This is L3 radiculopathy from a far lateral (foraminal) L3-L4 disc herniation. Far lateral herniations affect the EXITING root (L3 at L3-L4), not the traversing root. The negative SLR and positive femoral stretch test support upper lumbar root involvement. Anterior thigh pain and quad weakness are consistent with L3. Management follows same principles: conservative first, then surgery if failed. Surgical approach may differ - may need foraminotomy rather than standard laminotomy/discectomy. The exiting root must be decompressed, which may require more lateral dissection.

KEY POINTS TO SCORE

Far lateral herniation affects EXITING root (one level up)

L3-L4 far lateral = L3 root (not L4)

Femoral stretch test for upper lumbar roots

May need foraminotomy approach

COMMON TRAPS

✗Thinking L3-L4 disc always affects L4

✗Missing far lateral herniation on standard MRI (need parasagittal views)

✗Using standard medial approach for far lateral disc

LIKELY FOLLOW-UPS

"How does the surgical approach differ for far lateral disc?"

"What other structures can cause L3 symptoms?"

"How do you differentiate radiculopathy from hip pathology?"

Management Algorithm

LUMBAR RADICULOPATHY

High-Yield Exam Summary

ROOT PATTERNS

•L4: Knee extension weak, reduced knee jerk, medial leg
•L5: EHL weakness, NO reflex, dorsum foot/1st web space
•S1: Calf weakness, ABSENT ankle jerk, lateral foot/sole

KEY CLINICAL FEATURES

•Leg pain WORSE than back pain
•Dermatomal distribution of symptoms
•SLR positive at 30-70 degrees
•Crossed SLR = high specificity for disc

DISC MECHANICS

•Posterolateral herniation affects TRAVERSING root
•Far lateral herniation affects EXITING root (one level up)
•L4-L5 PL = L5 root; L4-L5 FL = L4 root
•Central herniation = risk of cauda equina

CAUDA EQUINA EMERGENCY

•Saddle anesthesia + urinary retention
•Bilateral leg symptoms
•MRI + surgery within 24-48 hours
•Delayed surgery = permanent deficits

MANAGEMENT PEARLS

•Conservative first: 6-12 weeks, 90% improve
•Microdiscectomy: 85-95% leg pain relief
•SPORT trial: surgery faster but similar long-term
•ESI: 50% avoid surgery at 1 year (Riew)

Root

Disc Level

Motor Weakness

Sensory Distribution

Reflex

L2-L3

Hip flexion, knee extension

Anterior thigh

None reliable

L3-L4

Tibialis anterior, Quadriceps

Medial leg, medial foot

Knee jerk (reduced)

L4-L5

EHL, Hip abduction, Tibialis posterior

Lateral leg, dorsum foot, 1st web space

None reliable

L5-S1

Gastrocnemius, Peroneals, Gluteus maximus

Lateral foot, sole, posterior calf

Ankle jerk (ABSENT)

Factor

Details

Prevalence

5-10% of patients with low back pain

Peak age

30-50 years (disc degeneration begins)

Gender

Slight male predominance (1.5:1)

Most common root

L5 (from L4-L5 disc)

Second most common

S1 (from L5-S1 disc)

Bilateral involvement

Rare - consider cauda equina or central disc

Disc Level

Exiting Root

Traversing Root

L3-L4

L4-L5

L5-S1

Herniation Type

Root Affected

Example

Posterolateral

Traversing root

L4-L5 PL herniation → L5 root

Far lateral (foraminal)

Exiting root

L4-L5 FL herniation → L4 root

Central

Cauda equina

Large central L4-L5 → multiple roots

Disc Terminology

Description

Bulge

Symmetric, circumferential extension

Protrusion

Focal, base wider than apex

Extrusion

Apex wider than base, through annulus

Sequestration

Free fragment, separated from disc

Type

Location

Root Affected

Clinical Features

Posterolateral

Lateral recess

Traversing root

Classic radiculopathy, SLR positive

Foraminal

Neural foramen

Exiting root

One level up, may be missed on MRI

Central

Central canal

Multiple roots

Bilateral symptoms, cauda equina risk

Extraforaminal

Far lateral

Exiting root

Femoral stretch test may be positive

Grade

Description

Clinical Implication

Normal power

No motor deficit

Movement against resistance

Mild weakness - conservative

Movement against gravity only

Moderate weakness - consider surgery

Movement with gravity eliminated

Severe weakness - surgery recommended

Flicker of contraction

Near complete deficit - urgent surgery

No contraction

Complete deficit - emergency surgery

Feature

Radiculopathy Pattern

Location

Leg > back (key feature)

Character

Sharp, shooting, electric

Distribution

Dermatomal (follows nerve root)

Aggravating

Sitting, coughing, straining, forward flexion

Relieving

Standing, lying, walking (unlike stenosis)

Test

Motor

Knee extension

EHL, hip abduction

Plantar flexion, hip extension

Reflex

Knee jerk

None reliable

Ankle jerk

Sensory

Medial leg/foot

Lateral leg, dorsum foot

Lateral foot, sole

Test

Technique

Positive Finding

Sensitivity/Specificity

SLR

Raise straight leg, hip flexed, knee extended

Pain 30-70° in radicular distribution

90% sensitive, 26% specific

Crossed SLR

SLR reproduces pain in opposite leg

Pain in contralateral leg

Low sensitivity, HIGH specificity (90%)

Femoral stretch

Prone, extend hip with knee flexed

Pain in anterior thigh

Positive for L4, L3 radiculopathy

Slump test

Seated, chin to chest, extend knee

Reproduces radicular pain

Tension test for dura

Sequence

What It Shows

T2 sagittal

Disc degeneration (dark disc), herniations, spinal alignment

T2 axial

Nerve root compression, lateral recess stenosis

Anatomy, fat in foramen (should be bright), bone marrow

STIR

Bone marrow edema, infection, tumor

Finding

Interpretation

Denervation changes

Positive waves, fibrillations at 3+ weeks

Reduced recruitment

Chronic nerve injury

Normal study

Does NOT rule out radiculopathy (may be too early)

Anatomical Relationships and Pathophysiology

Intervention

Evidence

Details

Activity modification

Strong

Avoid aggravating activities, NOT bed rest

NSAIDs

Strong

First-line pharmacotherapy

Oral steroids

Moderate

Short course (6 days) may help acute phase

Physical therapy

Strong

Core strengthening, McKenzie extension

Epidural steroid injection

Moderate

50% avoid surgery at 1 year (Riew)

Indication

Timing

Cauda equina syndrome

URGENT (24-48 hours)

Progressive motor deficit

Early (within days)

Severe weakness (MRC ≤3)

Early consideration

Failed conservative (6-12 weeks)

Elective

Intractable pain

Elective

Complication

Incidence

Prevention/Management

Dural tear

1-7%

Careful technique, primary repair, fibrin glue

Wrong level

0.1-0.3%

Intraoperative imaging, confirm with X-ray

Nerve root injury

0.1-0.5%

Adequate visualization, gentle retraction

Vascular injury

Very rare

Avoid plunging instruments anteriorly

Complication

Incidence

Management

Recurrent herniation

5-10%

May require revision surgery

Infection

1-2%

Antibiotics, possible washout

Epidural hematoma

Rare

Urgent decompression if symptomatic

Chronic pain (FBSS)

10-40%

Multidisciplinary management