Radiculopathies

Radiculopathy refers to the compression or irritation of the nerve roots as they exit the spinal cord and spinal column. It leads to symptoms (both motor and sensory) along the distribution of the nerve root.

Pathophysiology

Radiculopathies arises from compression and irritation of the spinal nerve roots. This leads to the release of inflammatory mediators, coupled with a reduced oxygen supply of the nerve due to the compression, which results in nerve damage. There is impaired nerve conduction which manifests as sensory disturbances and motor deficits. Chronic compression can lead to demyelination and axonal degeneration.

Let‘s look at some of the causes of radiculopathies:

• ⭐️ Vertebral disc herniation - this is most common cause
• Degenerative disc disease
• Spondylolisthesis - the anterior displacement of one vertebral body in relation to the vertebrae below.
• Bone changes/spondylosis - often secondary to rheumatoid arthritis or osteoarthritis. Osteophytes (bony spurs) end up encroaching on the space of the nerve root and compress it.
• Diabetes - can cause a painful thoracic or extremity radiculopathy by causing ischaemia of the nerve root.
• Infectious disorders/osteomyelitis - if they affect the nerve roots. For example, tuberculosis, histoplasmosis, herpes zoster infection, CMV-induced polyradiculopathy (a complication of HIV).
• 💡 Shingles usually causes a dermatomal radiculopathy (pain across the dermatome followed by rash), but may less commonly cause a motor radiculopathy with segmental weakness and reflex loss.
• Epidural abscess
• Scoliosis
• Tumours
• Iatrogenic causes - such as spinal surgery or epidural injections. These can lead to direct injury or may cause haematomas that can cause compression.

😷 Presentation

Radiculopathies present with pain, numbness or tingling radiating along a specific dermatomal distribution. This nerve root affected may be inferred by the symptoms present we can then couple this with imaging diagnostics to confirm the region of the nerve compression. As such it is vital to know the dermatomal distribution in the body. Motor deficits are also seen in the muscles supplied by nerves that have roots in the affected areas. Hyporeflexia may also be seen if certain nerves are compressed.

We will discuss cervical and lumbosacral radiculopathies. Thoracic radiculopathies are not very common.

😷

Cervical radiculopathies:

Common symptoms of all cervical radiculopathies:

• Neck pain - which may be accompanied by shoulder pain or headache.
• Difficulty with fine motor skills

Let’s look at more specific nerve roots and how they may present:

Radiculopathy	Causative disc	Sensory deficit	Motor deficit	Reduction of reflexes
C3/4	C2-C3, or C3-C4	Shoulder and neck area	Scapular winging	None
C5	C4-C5	Anterior shoulder	Biceps and deltoid	Biceps reflex
C6	C5-C6	From the upper lateral elbow over the radial forearm up to the thumb and radial side of index finger	Biceps and wrist extensors	Biceps & brachioradialis reflex
C7	C6-C7	Palmar and dorsal surface of fingers II-IV (half), and the dorsal surface of the middle of the forearm and arm all the way up	Triceps, wrist flexors and fingers extensors	Triceps reflex
C8	C7-T1	Palmar and dorsal fingers IV (half) and V, and the medial part of the forearm and arm	Finger flexors	None

We can perform some provocative manoeuvres to assess for nerve compression. For cervical radiculopathies, these are:

• Hoffman reflex - an UMN lesion relating to the cervical spine (usually due to spinal cord compression) may have a positive Hoffman’s sign. To perform the test, flick the patient’s middle finger with force whilst observing their index and thumb. A pisitive sign will show flexion of the index and thumb.
• Spurling manoeuvre (neck compression test) - can be done to screen for cervical radiculopathy. To perform the test, tilt and rotate the neck toward the affected side while applying downward pressure (axial loading) to the head. The test is positive if it produces pain and/or paraesthesia that radiates to the motor or sensory area of the affected nerve root. However, neck pain alone does not indicate a positive result.

😷

Lumbosacral radiculopathies

Radiculopathies affecting L4-S1 are more common than isolated lumbar or sacral radiculopathies. This is due to the curvature of the spine and resultant mechanical load experienced in this region.

Common symptoms of all lumbosacral radiculopathies:

• Lumbago (lower back pain) - the pain is experienced below the costal margin, above the buttocks.
• Sciatica - low back pain that radiates into the buttock and posterior thigh and leg. This is most commonly due to compression at L4-S1.
• Pain that worsens with lumbar flexion - as this is highly suggestive of lumbar disc herniation. Pain that improves with lumbar flexion is suggestive of spinal stenosis.

Radiculopathy	Causative disc	Sensory deficit	Motor deficit	Reduction of reflexes
L3	L2-L3	Anterolateral area of the thigh	Hip flexion
Knee extension
Hip adduction	Adductor & patellar reflexes
L4	L3-L4	Anterolateral thigh, over the patella, medial leg, medial malleolus	Knee extension
Hip adduction	Patellar reflex
L5	L4-L5	Lateral thigh and knee, anterolateral leg, dorsal foot and the big toe	Foot dorsiflexion → foot drop [difficulty heel walking]	Tibialis posterior reflex
S1	L5-S1	Lateral and dorsal thigh and leg, and lateral foot	Foot eversion and gastrocnemius muscle (foot plantar flexion) → difficulty toe walking	Achilles tendon reflex & lateral hamstring reflex
S2, S3, S4	A large central disc compressing the nerve roots intrathecally at a higher level (such as L5)	Posterior aspect of thigh and leg (S2), perineum (S3-4), and perianal (S5)	None	Bulbocavernous & anal reflex (anal wink)

• Straight leg raise test (Lasegue test): a straight leg raise (30-45º) leads to increased pain in the ipsilateral leg, with radiation to the motor or sensory areas of the affected nerve root. Sensitive but not specific.
• Bragard sign - after raising the leg, lowering it leg to just below the level where pain is produced and pulling the foot to dorsiflexion reproduces the pain.
• Crossed straight leg test - when the contralateral or unaffected leg is flexed at the hip, the patient experiences pain on the ipsilateral or affected side. This is highly specific for lumbar nerve roots, but not sensitive (it will exclude the cases that do not have radiculopathy, but might not detect the ones that have radiculopathy).

🔍 Investigations

As radiculopathy is secondary to a condition causing nerve compression, radiculopathy itself is a clinical diagnosis based on the history and clinical examination. However, the underlying cause can be investigated.

• Imaging is the most helpful, as disc herniations and degenerative disc diseases are the most common causes of
• 🏆 MRI (T2 weighted) - with T2-weighted images, it is easy to remember that 2 tissue types appear bright - fat and water. With a T1-weighted image, only 1 tissue type is bright - fat.

🧰 Management