This is a clinical diagnosis supported by electrophysiological findings on NCS/EMG

Clinical features of radiculopathy in general:

  • Motor or sensory involvement restricted to the distribution of an isolated nerve root level e.g. C5 nerve rooth or L5 nerve root.
  • The motor involvement may include weakness, atrophy or rarely faciculations in a myotome distribution.
  • The sensory involvement is numbness, loss of pin-prick or temperature sensation in a dermatomal distribution.
  • Pain distribution is of less localizing value due to referred pain and non-dermatomal pain distribution patterns
  • The reflexes are reduced or absent in the affected dermatome

Findings on investigations:

Neurophysiology NCS/EMG:

  • Reduced CMAP amplitude may occur
  • SNAP is typically normal as the process is proximal to the distal root ganglion
  • Denervation and reinervation of paraspinal muscles of affected nerve root
  • Denervation and reinervation features in myotome of affected nerve root


  • SNAP: normal amplitude, conduction velocity & latency i.e. disease proximal to the dorsal root ganglion
  • CMAP: usually normal, in some cases reduced amplitude may be seen. Normal conduction velocity & latency.
  • H-reflex (gastrocnemius-sleus): distinguishes S1 (abnormal H-reflex, side to side difference >1.5ms) & L5 (normal H-relfex) radiculopathies. H-reflex may be falsely negative & may be falsely positive in >60year olds.
  • F-waves: increased latency or absent. May be falsely normal.


  • Can be falsely negative in pure sensory radiculopathy.
  • Fibrillations & positive sharp waves PSW in affected myotomes (starts in paraspinals, then in proximal & then distal muscles). In definitive diagnosis: paraspinal muscles & 2 muscles supplied by different nerves but the same myotome show the changes.
  • MUAP (if reinnervation occurs): long duration, polyphasic.
  • Recruitment: may have reduced recruitment.

MRI features of neuro-foraminal stenosis:

  • Perineural intraforaminal fat reduction
  • Compression of foraminal zone
  • Hypertrophic facet joint (degenerative)
  • Foraminal nerve root impingement/compression
  • Size and shape of foramen is reduced

Investigations to consider:


  • May show the culprit lesion in cases of compression
    Is over-sensitive and may show lesions that are not clinically responsible for the symptoms
  • C-spine: degenerative disc disease, disc herniation, trauma
  • L-spine: degenerative disc disease, disc herniation (rare above L5), meningioma, neurofibroma, lipoma, metastasis

LP for CSF: Subarachnoid seeding, intrathecal metastasis/carcinomatous meningitis
CT-myelography: Subarachnoid seeding, intrathecal metastasis/carcinomatous meningitis, disc herniation, osteophytes
CT: causative lesions, false negatives with disc disease
X-rays: may be falsely negative

Individual radiculopathies:

C4 radiculopathy:

Motor: none
Sensory: shoulder, upper arm,
Pain: neck
Reflex: none

C5 radiculopathy:

Motor: Shoulder abduction, elbow flexion
Sensory: lateral arm
Pain: Neck, shoulder, scapula, anterior arm
Reflex: loss of biceps & brachioradialis

C6 radiculopathy:

Motor: elbow flexion (with hand midprone & supine), shoulder abduction
Sensory: thumb, index finger, radial forarm
Pain: neck, shoulder, anterior upper arm, antecubital fossa
Reflex: loss of biceps & brachioradialis

C7 radiculopathy:

Motor: elbow extension, wrist extension, wrist flexion, shoulder adduction
Sensory: middle finger +/-dorsal & lateral forearm
Pain: neck, shoulder, dorsum of the forearm
Reflex: loss of triceps reflex

C8 radiculopathy:

Motor: finger flexion,
Sensory: medial hand (ring little finger & hypothenar eminence)
Pain: neck, shoulder, ulnar forearm
Reflex: none

T1 radiculopathy:

Motor: small hand muscles
Sensory: ulnar forearm
Pain: neck, shoulder, ulnar arm
Reflex: none

L1 radiculopathy:

Motor: none
Sensory: inguinal
Pain: inguinal pain
Reflex: none

L2 radiculopathy:

Motor: hip flexion
Sensory: anterior upper, middle & lateral thigh
Pain: anterior thigh & leg
Reflex: none

L3 radiculopathy:

Motor: hip flexion, hip adduction, knee extension
Sensory: medial thigh, knee
Pain: anterior thigh, groin, leg
Reflex: loss of adductor reflex

L4 radiculopathy:

Motor: Mild knee extension, hip adduction, ankle dorsiflexion
Sensory: medial calf & medial foot
Pain: anterior thigh, anterior & medial leg
Reflex: loss of knee reflex

L5 radiculopathy:

Motor: large toe extension, hip abduction, ankle inversion
Sensory: dorsum of the foot, large toe & lateral calf
Pain: posterior & lateral thigh & calf, large toe, dorsum of the foot
Reflex: internal hamstring reflex

S1 radiculopathy:

Motor: ankle plantar flexion, toe curling
Sensory: sole of the foot, lateral foot, posterior calf
Pain: posterior & lateral thigh & calf, lateral toes, heel
Reflex: loss of ankle reflex & biceps femoris reflex (lateral hamstring reflex)

S2-4 radiculopathy:

Motor: none
Sensory: posterior thigh S2, behind the knee S2, medial buttocks S3, perineum S3-4, perianal S4
Pain: medial buttocks
Reflex: bulbocavernosus, anal wink

Cauda equina syndrome:

A combination of nerve roots L1-S4
Lateral cauda equina syndrome: L4, L3, L2
Medial cauda equina syndrome from inside a.k.a. conus lesion: S5, S4 ,S3
Medial cauda equina syndrome from outside: bilateral S2,S3, L2, L3

Related articles:


  1. Mamisch N, Brumann M, Hodler J, Held U, Brunner F, Steurer J; Lumbar Spinal Stenosis Outcome Study Working Group Zurich. Radiologic criteria for the diagnosis of spinal stenosis: results of a Delphi survey. Radiology 2012; 264:174–179
  2. Gustav Andreisek G, Imhof M, Wertli M, Winklhofer S, Pfirrmann C, Hodler J, Steurer J; Lumbar Spinal Stenosis Outcome
  3. Study Working Group Zurich.  A Systematic Review of Semiquantitative and Qualitative Radiologic Criteria for the Diagnosis of Lumbar Spinal Stenosis. AJR 2013; 201:W735–W746