PANCE Blueprint Musculoskeletal (10%)

Herniated nucleus pulposus

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?

Picmonic Picmonic
IM_NUR_HerniatedDisc_v1.2_ Herniated disk, also referred to as 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.

View Herniated Nucleus Pulposus Picmonic

IM_MED_DermatomesCervical_v1.2_ 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 skin to the brain.

Cervical Spine

Cervical herniated disk

  • 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 nerve root radiculopathy

Lumbar Spine

Lumbar herniated disk

Patient will present with → 99% will have radiculopathy and symptoms and signs in the distribution of affected nerve roots. Pain usually develops suddenly, radiates below the knee and back pain is typically relieved by bed rest

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


  • Non contrast 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
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.
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