Lower Back Pain, LBP
Red Flags of Lower Back Pain
*Age older than 50, more than 6 weeks of pain, previous cancer history, severe pain, constitutional symptoms, neurlogical deficits, and loss of anal sphincter tone*
Physical Exam Findings of Spinal Stenosis
*Kemp sign*: unilateral radicular pain from foraminal stenosis made worse by extension of back. *Straight leg raise* (nerve root tension sign) is usually negative. *Valsalva test* does not worsen pain (pain is worse in the case of herniated disc).
Treatment of Disc Herniation
*NSAID* in scheduled doses, physical therapy, and local heat lead to resolution within 4 weeks in 80% of cases. DO NOT PRESCRIBE BEDREST as most LBP is mechanical, continuation of regular activities preferred. Epidural injection or nerve block may be beneficial.
Nonoperative Treatment of Spinal Stenosis
*NSAIDS, physical therapy* to strengthen abdominal muscle, weight loss and bracing. *Steroid injections* either epidural and/or transforaminal for advanced symptoms
Physical Examination of Herniated Disc
*passive straight leg raise increases pain*, highly sensitive but not specific. *crossed straight leg raise increases pain* is highly specific but not sensitive.
Operative Treatment of Spinal Stenosis
*surgical laminectomy* may achieve short term success but many patients have recurrence
Herniated disc
Causes include degenerative changes, trauma, neck/back strain or sprain. Most common in *lumbar region, especially at *L5-S1* (most common) & *L4-L5* (2nd most common). Common among middle to old aged men.
Motor & Sensory Deficits in Back Pain: Nerve root *L5*
Motor deficit: Big toe dorsiflexion - extensor hallucis longis, Foot eversion - peroneus muscles affected. Reflex deficit: Nil. Sensory deficit: Foot dorsum & lateral aspect of lower leg.
Motor & Sensory Deficits in Back Pain: Nerve root *S1*
Motor deficit: Plantar flexion - grastrocneumius/soleus, hip extension - gluteus maximus affected. Reflex deficit: Achilles. Sensory deficit: Plantar & lateral aspects of foot.
Motor & Sensory Deficits in Back Pain: Nerve root *L4*
Motor deficit: foot dorsiflexion, tibialis anterior affected. Reflex deficit: Patellar. Sensory deficit: Medial aspect of lower leg.
Spinal Stenosis
Narrowing of lumbar or cervical spinal canal, leading to compression of nerve roots and spinal cord. Most commonly due to degenerative joint disease; typically occurs in middle aged or elderly.
H&P of Spinal Stenosis
Neck/back pain that *radiates to arms or the buttocks & legs*, arm/leg weakness/numbness. In lumbar stenosis: leg cramp worsens with standing & walking; symptoms improve with hip flexion & bending forward, as it relieves pressure on nerves.
Diagnosis of Herniated Disc
Obtain ESR & plain radiograph if other causes of LBP suspected. X-ray may show disk herniation. Order MRI if symptoms refractory to conservative management
Large midline herniations may cause *Cauda Equina Syndrome*
Presents with bowel or bladder dysfunction (urinary overflow incontinence), impotence & saddle area anesthesia. A *surgical emergency*. Order STAT MRI for cauda equina syndrome or severe/rapidly progressive neurological deficit.
H&P of Herniated disc
Presents with sudden onset of severe, electricity like LBP, usually preceded by several months of aching, discogenic pain. Exacerbated by increased intra-abdominal pressure or Valsalva maneuvers. Associated with *sciatica, paresthesias, muscle weakness, atrophy, contractions, spasms.*
Diagnosis of Spinal Stenosis
Radiographs show degenerative changes including disk space narrowing, facet hypertrophy, spondylolisthesis, leading to narrowed spinal canal. MRI or CT shows spinal stenosis.
Surgical intervention of Disc herniation
Severely or rapidly evolving NE deficits & cauda equina syndrome are indications. Most common procedure for herniated/ruptured disk is microdiscectomy, where a small incision is made, aided by an operating microscope, and a hemilaminotomy to remove disk fragment that is impinging on nerves.
