PANCE Blueprint Musculoskeletal (8%)

Herniated nucleus pulposus (Lecture)

Symptoms will follow a dermatomal distribution

A patient complains of loss of sensation at the level of the umbilicus. Which of the following dermatomes is affected?

Cervical Spine

Cervical herniated disk

Patient will present as → a 57-year old male with right arm pain of 4 weeks duration. He reports the pain began following a tennis match and has not improved with time. He describes the pain as an aching sensation that affects his lateral forearm that improves when he abducts the shoulder. He also describes a sensation of numbness in this right thumb. The reflex exam shows he has 1+ right biceps reflexes and 2+ right triceps reflexes which are both symmetric with the left side. A sensory exam shows paresthesias in the distribution of the right thumb. Motor exam shows no evidence of radial deviation with active wrist extension. Motor exam on the right shows 5/5 deltoid, 5/5 elbow flexion with the palms facing upward, 4/5 wrist extension, and 5/5 elbow extension, and 5/5 wrist flexion.

The clinical presentation is most consistent with C6 radiculopathy. This would be caused by a paracentral cervical disc herniation at C5/6. 

Usually posterolateral at C5-C6, C6-C7

  • Young middle age mid 30's
  • Cervical disk: Pain into the arm/shoulder pain, numbness and tingling pain into the arm with pain at restversus rotator cuff no pain at rest unless there is movement
  • MRI is confirmatory – soft collar, NSAIDS, muscle relaxants, epidural steroid injections, surgical consultation if not responsive to conservative treatments

Cervical radiculopathy

  • C4
    • May affect the levator scapular and trapezius muscles, resulting in weakness in shoulder elevation. There is no reliable associated reflex.
  • C5
    • Weakness of the rhomboid, deltoid, bicep, and infraspinatus muscles. Patients may have weakness of shoulder abduction and external rotation. The bicep reflex may be diminished.
  • C5-C6
    • Affects the C6 nerve root and produces pain at the shoulder tip and trapezius with radiation to the anterior upper armradial forearm, and thumb, and sensory impairment in these areas. C6 radiculopathy can easily be confused for C5 or C7 radiculopathy. Weakness can overlap with the C5 or C7 muscles. Muscles affected include infraspinatus, bicep, brachioradialis, pronator teres, and triceps. Weakness involves flexion at the elbow, or shoulder external rotation. The bicep or brachioradialis reflex may be diminished.
  • C6-C7
    • Affects the C7 nerve root and produces pain at the shoulder blade, pectoral area, and medial axilla with radiation to posterolateral upper arm, dorsal elbow and forearmindex and medial digits or all of the fingers, and sensory impairment in these areas. C7 radiculopathy can result in weakness of the triceps, pronator teres, flexor carpi radialis. Weakness involves the elbow extensors and forearm pronators. There may be a diminished triceps reflex.
  • C7-T1
    • Causes C8 radiculopathy. Weakness can be present in the opponens pollicis, flexor digitorum profundus, flexor pollicis longus, and hand intrinsic muscles. Clinically, patients present with symptoms similar to an ulnar or median motor neuropathy and can have weakness of finger abductors and grip strength; they may also have findings suggesting median motor neuropathy. No reliable reflex test is available.
Disk space Nerve root Muscle Reflex Sensory
C4-5 C5 Deltoid, supraspinatus, infraspinatus Biceps Lateral arm
C5-C6 C6 Biceps, wrist extensors Biceps, brachioradialis Radial forearm, thumb, index finger
C6-7 C7 Triceps, wrist flexors, finger extensors Triceps Middle finger
C7-T11 C8 Finger flexors None Fourth and fifth fingers
T1-2 T1 Finger abductors None Ulnar forearm
Lumbar Spine

Lumbar herniated disk

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Patient will present as → a 35-year-old male presents with a three-month history of low back pain and right leg pain that has failed to improve with nonoperative modalities including selective nerve root corticosteroid injections. Leg pain and paresthesias are localized to his buttock, lateral and posterior calf, and the dorsal aspect of his foot. On strength testing, he is graded a 4/5 for plantar-flexion and 4+/5 to ankle dorsiflexion. On flexion and extension radiographs there is no evidence of spondylolisthesis. Sagittal and axial T2-weighted MRI images are obtained.

The clinical presentation is consistent with a lumbar disc herniation with symptoms of a combined L5 and S1 radiculopathy 

Diagnosis of Lumbar Disk Herniation

Pain in a dermatomal pattern - increases with coughing, straining, bending, and sitting

  • L5-S1 is most common
  • Also L4-L5

Clinical Manifestations

  • Sciatica: back pain radiating through the thigh and buttocks - lower leg (below knee) down L5-S1 dermatome
  • Physical Exam: + straight leg raise, + crossover test


  • Noncontrast MRI is confirmatory


  • NSAIDS, rest, steroids and physical therapy
  • Epidural steroid injections
  • Surgery if warranted

Look for "red-flag" symptoms:

  • fecal incontinence
  • Saddle anesthesia
  • Urinary retention
  • Immunosuppression
  • Intravenous drug use
  • Unexplained fever
  • Chronic steroid use
  • progressive or disabling symptoms
  • Focal neurologic deficit
  • Fracture or infection
  • Significant trauma at any age
  • Older than 50 years, and mild trauma
  • Neoplasm or fracture
  • History of cancer (i.e., weight loss)
  • Unexplained weight loss
  • No improvement after six weeks of conservative management

Lumbar radiculopathy most commonly involves either the L5 or S1 root.

  • L1
    • Rare - symptoms involve pain, paresthesia, and sensory loss in the inguinal region.
  • L2, L3, and L4
    • In older patients with spinal stenosis. They are generally considered as a group because of marked overlap of innervation of the anterior thigh muscles. Acute back pain is the most common presenting complaint, often radiating around the anterior aspect of the thigh down into the knee.
  • L5
  • S1
    • Pain radiates down the posterior aspect of the leg into the foot from the back. On examination, strength may be reduced in leg extension (gluteus maximus) and plantar flexion. Sensation is generally reduced on the posterior aspect of the leg and the lateral footAnkle reflex loss is typical.
  • S2, S3, and/or S4
    • Patients can present with sacral or buttock pain that radiates down the posterior aspect of the leg or into the perineum. Weakness may be minimal, with urinary and fecal incontinence as well as sexual dysfunction. 
L4 L5 S1
  • Anterior thigh pain
  • Sensory loss medial ankle
  • Lateral thigh/leg and groin paresthesia and pain
  • Dorsum of the foot especially between 1st and 2nd toes
  • Posterior leg/calf
  • Plantar surface of the foot
  • Angle dorsiflexion
  • Big to extension
  • Walking on heels more difficult than on toes
  • Plantar Flexion
  • Walking on toes more difficult than on heels
Reflex Diminished
  • Loss of knee jerk
  • Weak knee extension - quads
  • Usually no diminished reflexes.
  • Loss of ankle jerk
Lumbar back pain localizing nerve levels

Question 1
Which of the following statements about lumbar disc disease is true?  
It usually involves the L5-S1 interspace
It typically involves anterior herniation of the nucleus pulposus
It usually requires surgical intervention
Treatment involves strict bed rest for 1 to 2 weeks
Forward flexion of the trunk often helps relieve symptoms
Question 1 Explanation: 
Lumbar disc disease usually results from posterior herniation of the nucleus pulposus that impinges on the spinal cord. The most common site is the L5-S1 interspace, which affects the first sacral nerve root. Patients typically recall a precipitating event such as lifting a heavy object. Symptoms include severe back pain that radiates to the legs and is aggravated by coughing, sneezing, or forward flexion of the trunk. The condition is the most common cause of sciatica. Examination may show decreased sensation in a dermatome pattern, weakness, decreased reflexes, and a positive straight leg-raising test. In severe cases, patients may experience bowel or bladder incontinence. Radiographs and laboratory tests are generally unnecessary, except in the few patients in whom a serious cause is suspected on the basis of a comprehensive history and physical examination. Surgical evaluation is indicated in patients with worsening neurologic deficits or intractable pain that is resistant to conservative treatment. Bed rest should not be recommended for patients with nonspecific acute low back pain. Moderate quality evidence suggests that bed rest is less effective at reducing pain and improving function at 3 to 12 weeks than advice to stay active. Prolonged bed rest can also cause adverse effects such as joint stiffness, muscle wasting, loss of bone mineral density, pressure ulcers, and venous thromboembolism (VTE). The treatment plan should be reassessed in patients who do not return to normal activity within 4 to 6 weeks. Most mild cases can be treated with the limitation of aggravating activity, anti-inflammatory agents, and muscle relaxants.
Question 2
A 26-year-old male was lifting a heavy object two weeks ago when he felt a sudden onset of low back pain. He describes pain in the low mid back at the belt line aggravated with movement. Radicular symptoms are noted in the left buttock down the leg to the dorsal aspect of the foot. He denies any urine or bowel complaints His examination demonstrates an inability to stand on his toes and a positive straight leg raise. Which of the following is most appropriate diagnostic study in this patient?
Computed tomography (CT)
Computed tomography (CT)
Magnetic resonance imaging (MRI)
MRI is the diagnostic study of choice in a patient with suspected disc herniation.
MRI is the diagnostic study of choice in a patient with suspected disc herniation.
Question 2 Explanation: 
MRI is the diagnostic study of choice in a patient with suspected disc herniation.
Question 3
What spinal nerve root is most likely affected in a patient with weak wrist extension, thumb and index finger paresthesias and diminished triceps reflex?
Cervical 4
See C for explanation
Cervical 5
See C for explanation
Cervical 6
Cervical 7
See C for explanation
Question 3 Explanation: 
In contrast, cervical 5 would be associated with deltoid and biceps weakness and diminished biceps reflex while cervical 7 would result in triceps weakness and paresthesias in the middle finger and diminished brachioradialis reflex.
Review Topic: Herniated nucleus pulposus
Question 4
A 65-year-old male presents with back pain two days after he was shoveling snow. The patient complains of pain in his low back that radiates into his buttocks, posterior thigh and calf, and the bottom of his foot. There is associated numbness of his lateral and plantar surface of his foot. Which of the following disc herniations is most likely to be affected?
See C for explanation
See C for explanation
See C for explanation
Question 4 Explanation: 
The S1 nerve root impingement is most likely to occur from the herniation of the L5-S1 disc space. The S1 disc affects Achilles' reflex, the gastrocnemius and soleus muscles, and the abductor hallucis and gluteus maximus muscles.
Review Topic: Herniated nucleus pulposus
There are 4 questions to complete.
Shaded items are complete.
osmosis Osmosis

IM_NUR_HerniatedDisc_v1.2_A herniated disk also referred to as a herniated nucleus pulposus (HNP), is a structural deterioration of the intervertebral discs that provide shock absorption for the spine. Also known as “slipped disc,” damage to the disc enables the nucleus pulposus to seep through the torn or stretched annulus and bulge outward between the vertebrae. HNP frequently occurs between L5-S1 or the fourth and fifth lumbar vertebrae. Causes of HNP include natural degeneration, spine trauma, and spinal stenosis. Assessment findings include radiating pain, lower extremity weakness, and bowel/bladder incontinence. Diagnostic studies to determine structural defects and locate damaged sites include x-rays, myelogram, MRI, and CT scan. Interventions for HNP include wearing a brace to support the spine. Medications include NSAIDs, opioids, analgesics, epidural corticosteroids, muscle relaxants, and antidepressants. Invasive procedures indicated for patients with HNP include intradiscal electrothermal plasty (IDET), interspinous process decompression, laminectomy, discectomy, spinal fusion, and artificial disc replacement.

Herniated Nucleus Pulposus
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The skin’s surface is divided into specific areas called dermatomes, which are mainly supplied by a single spinal. There are 8 cervical nerves (C1 being an exception with no dermatome), 12 thoracic nerves, 5 lumbar nerves, and 5 sacral nerves. Each of these nerves relays sensation (and pain) from a particular region of the skin to the brain.

Dermatomes – Cervical
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Dermatomes – Thoracic 
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Dermatomes – Lumbosacral
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