Sciatica (ischias) refers to a cluster of symptoms resulting from irritation or compression of neural structures in the lumbosacral region, producing pain radiating along the dermatomes of the lower limb — most commonly L5 and S1.
Pain typically begins in the lumbosacral area, travels through the buttock and the posterolateral thigh, and may extend to the leg and foot. Paresthesia, motor weakness and altered reflexes may accompany the pain.
Etiology — more than “a disc pressing on the nerve”
Common causes include:
- Lumbar disc herniation
- Degenerative changes with canal or foraminal stenosis
- Spondylolisthesis
- Inflammatory and neoplastic processes
Current literature emphasizes that pathogenesis involves not only mechanical compression, but also:
- Neuro-inflammation (cytokines, chemokines, inflammatory mediators)
- Peripheral and central sensitization
- Impaired root perfusion
- Secondary alterations in the mechanics of perineural tissues
This helps explain the frequent mismatch between MRI findings and symptom severity
“Sciatica mimickers” — when it looks like radiculopathy, but isn’t
A key element of modern clinical reasoning is recognizing that not every leg-pain pattern is true radiculopathy.
Frequent mimickers include:
1) Ligament-related pain and enthesopathies
Overloaded ligaments and entheses may produce referred pain into the buttock or thigh, often posture-dependent.
2) Myofascial trigger points and taut bands within:
- Gluteal muscles
- Deep hip rotators
- Lumbar extensors
Can generate referred pain along the limb, typically without neurological deficits
3) Fascial dysfunction:
- Modulate muscle tone
- Limit neural movement relative to surrounding tissues
- Provoke pulling, sometimes nocturnal, pain patterns
4) Extra-spinal entrapment neuropathies:
- Piriformis syndrome
- Deep gluteal syndrome
- Pelvic entrapment, scarring, post-traumatic changes
These conditions may clinically resemble radiculopathy, yet neurological examination remains largely normal.
Clinical picture and testing. Features supporting true radiculopathy:
- Dermatomal L5/S1 distribution
- Positive neurodynamic tests (SLR, Bragard)
- Sensory loss in a dermatome
- Segmental weakness
- Reduced tendon reflexes, possible foot drop
Features favoring soft-tissue origin:
- Symptoms reproduced with palpation
- Non-dermatomal distribution
- Positional variability
- Absence of relevant neurological deficits
Risk factors:
- Prolonged sitting, lifting, repeated trunk rotation
- Obesity, smoking, low physical activity
- Psychosocial stress, poor sleep
- Genetic predisposition to disc degeneration
Red flags. Urgent evaluation is required in the presence of:
- Cauda equina symptoms (bladder/bowel dysfunction, saddle anesthesia)
- Rapidly progressive motor deficits
- Systemic signs (fever, weight loss, history of cancer)
- Traumatic onset in patients with osteoporosis
- Clinical take-home points