# Clinical Cases: Back - Muscles and Nerves

## Case 1: Lumbar Strain with Paraspinal Muscle Spasm

### Clinical Image
![Lumbar Spine MRI](case_01_image.jpg)
*Source: [Wikimedia Commons - Lumbar MRI](https://commons.wikimedia.org/wiki/File:Low_back_pain_MRI.jpg) - CC BY-SA 3.0*

### Case Presentation
A 35-year-old office worker presents with acute onset of lower back pain that began yesterday while moving furniture. He describes the pain as a dull ache across his lower back that increases with movement and is relieved by lying flat. He denies any radiation of pain into his legs, numbness, tingling, or weakness. There is no history of trauma, fever, weight loss, or bowel/bladder dysfunction. Physical examination reveals paravertebral muscle tenderness and palpable spasm bilaterally at the L4-L5 level. Range of motion is limited in all directions due to pain and guarding. Straight leg raise is negative bilaterally. Neurological examination including strength, sensation, and reflexes in the lower extremities is completely normal. Given the lack of red flag symptoms and normal neurological examination, imaging is deferred per clinical guidelines. The patient is diagnosed with acute mechanical low back pain from lumbar strain and paraspinal muscle spasm. He is treated with NSAIDs, muscle relaxants, and advised to continue gentle activity as tolerated, avoiding bed rest. Physical therapy is prescribed focusing on core strengthening and proper body mechanics.

### Key Learning Points
- The erector spinae group (iliocostalis, longissimus, spinalis) are primary extensors of the vertebral column
- Paraspinal muscles can go into protective spasm following injury, limiting motion and causing pain
- Mechanical low back pain is the most common cause of back pain and has a favorable natural history
- Red flag symptoms (cauda equina syndrome, progressive neurological deficit, malignancy, infection) require urgent evaluation
- Imaging is not indicated for acute low back pain without red flags in the first 4-6 weeks

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## Case 2: Spinal Accessory Nerve Injury

### Clinical Image
![Spinal Accessory Nerve](case_02_image.jpg)
*Source: [Wikimedia Commons - Spinal Accessory Nerve](https://commons.wikimedia.org/wiki/File:Spinal_accessory_nerve.png) - CC BY-SA 4.0*

### Case Presentation
A 48-year-old woman presents with progressive difficulty raising her left arm overhead and chronic aching pain in her left shoulder region 6 weeks after undergoing lymph node biopsy in the posterior triangle of her neck for evaluation of cervical lymphadenopathy. She notes that her shoulder appears to "droop" and she has trouble carrying her purse on that side. Physical examination reveals asymmetry of the shoulders with the left shoulder sitting lower than the right. The left scapula is laterally displaced and rotated, with the inferior angle closer to the spine. When asked to abduct her arm, she has weakness initiating abduction and the scapula wings laterally. Shoulder shrug is weak on the left, and she cannot resist downward pressure on the shoulder. Formal examination reveals weakness of left trapezius muscle (unable to shrug against resistance) with preserved sternocleidomastoid function. EMG/nerve conduction studies confirm spinal accessory nerve injury in the posterior triangle. She is referred for physical therapy focusing on periscapular strengthening and referred to a peripheral nerve surgeon for possible nerve exploration.

### Key Learning Points
- The spinal accessory nerve (CN XI) innervates the trapezius and sternocleidomastoid muscles
- The nerve courses superficially through the posterior triangle of the neck, making it vulnerable during surgery
- Trapezius weakness causes shoulder droop, lateral scapular winging, and difficulty with arm abduction above 90 degrees
- The posterior triangle is bordered by the sternocleidomastoid anteriorly, trapezius posteriorly, and clavicle inferiorly
- Iatrogenic injury during lymph node biopsy or neck dissection is a recognized complication

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## Case 3: Cervical Radiculopathy from Foraminal Stenosis

### Clinical Image
![Cervical Foraminal Stenosis](case_03_image.jpg)
*Source: [Wikimedia Commons - Cervical Spine MRI](https://commons.wikimedia.org/wiki/File:Cervical_MRI.jpg) - CC BY-SA 3.0*

### Case Presentation
A 55-year-old accountant presents with 2 months of progressive right-sided neck pain radiating into her shoulder, lateral arm, and into her thumb and index finger. The pain is described as sharp and burning, worse when tilting her head to the right or looking up. She reports numbness in her thumb and weakness when trying to flex her elbow and turn her palm up. She works at a computer and has noticed difficulty with fine motor tasks. Physical examination reveals limited cervical extension and right lateral rotation due to pain. Spurling test (cervical extension with lateral rotation to the right and axial compression) reproduces her radicular symptoms. Neurological examination demonstrates weakness of right biceps and brachioradialis (4/5), decreased sensation over the lateral forearm, thumb, and index finger (C6 dermatome), and diminished biceps and brachioradialis reflexes. MRI of the cervical spine shows right-sided C5-C6 foraminal stenosis from uncovertebral joint hypertrophy and facet arthropathy causing C6 nerve root compression. She is started on gabapentin, referred for physical therapy with cervical traction, and scheduled for a cervical epidural steroid injection.

### Key Learning Points
- Cervical spinal nerves exit above their corresponding vertebrae (C6 nerve exits at C5-C6 foramen)
- C6 radiculopathy causes biceps/brachioradialis weakness, decreased biceps reflex, and lateral forearm/thumb sensory loss
- The intervertebral foramen is bordered by the uncovertebral joint anteriorly and facet joint posteriorly
- Spurling test compresses the foramen and reproduces radicular symptoms in cervical radiculopathy
- Unlike lumbar disc herniations, cervical radiculopathy is more commonly caused by foraminal stenosis from arthritis