Can Muscle Spasm Cause Straightening of Lumbar Lordosis?
Yes, muscle spasm can cause straightening (loss) of lumbar lordosis, though this is typically a temporary radiographic finding associated with acute pain rather than a primary pathologic mechanism.
Mechanism and Clinical Context
Muscle spasm in the lumbar paraspinal muscles can lead to loss of the normal lumbar lordotic curve through sustained involuntary muscle contraction. However, the relationship between muscle spasm and lordosis changes is complex:
Muscle spasm does not directly cause pain or tenderness in the lower back despite its visible presence on examination. In patients with lumbar disc herniation presenting with sciatic scoliosis (where muscle spasm is evident), pressure pain thresholds were not lower on the spasmodic (concave) side compared to the convex side 1.
The spasm itself appears to be a secondary phenomenon rather than the primary pain generator. Studies show that areas of tenderness and pain extend beyond the innervation territory of affected nerve roots, suggesting central nervous system hyperexcitability rather than the muscle spasm itself as the pain source 1.
Clinical Presentations Where This Occurs
Acute Traumatic Settings
Post-trauma muscle spasm commonly limits cervical mobility and can alter spinal alignment. After trauma, it is common for patients to exhibit limited spinal mobility because of muscle spasm, and spinal instability may only become apparent near the terminal point of flexion or extension 2.
Loss of cervical lordosis is frequently seen on imaging after whiplash-type injuries, though this may represent positioning and muscle guarding rather than structural injury 2.
Chronic Neuromuscular Conditions
Stiff-person syndrome presents with progressive difficulty bending forward and increasing lumbar lordosis (paradoxically), followed by severe spasms. This represents a distinct pathophysiologic process involving antibodies against glutamic acid decarboxylase 3.
Neuromuscular disorders can produce lumbar hyperlordosis (not loss of lordosis) through chronic muscle imbalance, requiring surgical correction when severe 4.
Important Clinical Distinctions
What Muscle Spasm Does NOT Indicate
Muscle spasm presence does not correlate with structural instability. The spasm is a protective response but does not reliably indicate ligamentous injury or the need for surgical intervention 2.
Radiographic loss of lordosis from muscle spasm is typically reversible once the underlying pain generator is addressed, unlike structural causes of lordosis loss 5.
Red Flags Requiring Further Investigation
When evaluating straightening of lumbar lordosis, consider these serious underlying conditions:
Spinal cord tethering can present with progressive musculoskeletal deformities including exaggerated lumbosacral lordosis (not loss of lordosis), along with pain, sensorimotor disturbances, and bladder/bowel dysfunction 2.
Structural spinal pathology including fractures, infections, or tumors should be excluded when lordosis changes are accompanied by neurologic deficits, severe progressive pain, or constitutional symptoms 6, 7.
Imaging Interpretation Pitfalls
Loss of lumbar lordosis on static radiographs may simply reflect patient positioning, pain-related guarding, or muscle spasm rather than true structural pathology 2.
MRI is the preferred imaging modality when nerve root compression or intraspinal pathology is suspected, regardless of lordosis appearance on plain films 6.
Flexion-extension views may be inadequate in the acute setting due to muscle spasm limiting motion, but can be useful in the outpatient setting once acute symptoms resolve 2.
Clinical Management Approach
The straightening of lumbar lordosis from muscle spasm should be managed by addressing the underlying pain generator:
Conservative management including pain control and gradual mobilization is appropriate for most cases, as the lordosis typically normalizes once muscle spasm resolves 2.
Persistent loss of lordosis beyond 6 weeks despite conservative treatment warrants MRI evaluation to exclude structural pathology, particularly if radicular symptoms are present 6.
Document specific clinical findings including radicular pain distribution, dermatomal sensory deficits, motor weakness, and reflex changes to guide imaging decisions and treatment planning 6.