AssessmentsBack pain: Pathology review
USMLE® Step 1 style questions USMLE
A 30-year-old male comes to the physician due to back pain. 2 months ago, he started having back pains which he attributed to the strenuous interval training he attended at that time. The patient discloses morning pain and stiffness which improves after his morning exercise routine. The pain often awakes him at night, but he is able to go back to sleep. On physical examination, pain is reproduced with palpation of the sacroiliac joint and spinal flexion is limited. Estimated erythrocyte sedimentation rate is 75 mm/hr. This patient’s condition is also associated with which of the following?
At the urgent care clinic, three people came in with lower back pain. The first is Jeff, a 26-year-old, who says his pain began 5 hours ago after trying to lift a 300-pound weight off of the floor at his local gym. He describes the pain as sharp and severe and says the pain goes down the back of his right leg and into his foot. Physical examination reveals a positive straight leg raise test on the right, and a diminished right Achilles tendon reflex. Second is Beth, a 68-year-old, who says she slipped and fell while walking in her kitchen yesterday. Her history includes a wrist fracture from a little over a year ago. Physical examination shows midline spinal tenderness to palpation. Finally, we have Harry, a 71-year-old male, who says his back pain has progressively worsened over the past month, keeping him up at night. He also reports increased urinary frequency.
Back pain is a very common complaint and one for which there are many potential causes. It can originate from the spinal cord, nerve roots, the vertebral column, the surrounding muscles, and ligaments, or even extra-spinal structures, such as abdominal organs. Therefore, the causes of back pain can be subdivided into mechanical causes, such as muscle strain, spinal osteoarthritis, disc herniation, spinal stenosis, vertebral fractures and osteoporosis; and non-mechanical causes, such as bone metastasis, seronegative spondyloarthritis, and vertebral osteomyelitis.
First, let’s start with musculoskeletal causes. The vast majority of cases of back pain are considered non-specific musculoskeletal pain due to strained muscles or ligaments. These individuals have no sensory or motor deficits, and they typically complain about tenderness over the affected muscle or ligament. The treatment for these individuals is prescribing activity as tolerated and NSAIDs for pain management. The next one is spinal osteoarthritis, which can be due to the natural aging process where the cartilage at the tips of bones wear down over their lifetime. It is associated with joint degeneration, ligamentous changes, disc degeneration, and finally, deformity of the spine.
Next we have disk herniation. Now, the spine is made up of bony vertebrae separated by intervertebral disks that act like cushions to absorb shock. The intervertebral discs consist of a thick, tough, fibrous outer ring called the annulus fibrosus surrounding a soft gelatinous core called the nucleus pulposus. In disk herniation, the nucleus pulposus bulges outward, almost always posteriorly, since the posterior longitudinal ligament is relatively thin compared to the wide anterior longitudinal ligament.. This is most often caused by an individual doing some heavy lifting, and while any disk in the spine can herniate, a high yield fact to know is that it is almost always one of two disks in the lumbosacral region that herniates, the L4-L5 disk or the L5-S1 disk. But, on rare occasions, the disk between L3-L4 vertebrae can also herniate. Regardless of the disc that herniates, the nerve that is affected is typically below the level of herniation. A key symptom for L4-5 and S1-3 disc herniations is sciatica, or a shocking pain that shoots down from the buttocks through the leg, following the course of the sciatic nerve. In L4 radiculopathy, where the disk between L3-L4 herniates, there’s also motor deficits like weakness in knee extension and reduced patellar reflex. On the other hand, if the L4-L5 disk herniates, it can result in L5 radiculopathy. The motor deficits include weakened hip abduction and foot dorsiflexion. Another high yield point that you have to know for your exam is that individuals with L4 or L5 radiculopathy have difficulty in heel walking! Finally, if the L5-S1 disk herniates, it can lead to S1 radiculopathy. Motor deficit includes weakened foot plantar flexion and a diminished Achilles tendon reflex. Finally, remember that individuals with S1 radiculopathy have difficulty in toe walking. A common test used in diagnosing lumbar disk herniation is the straight leg raise test, or SLR, where a person laying on their back keeps their legs straight and then raise them one at a time between 30 and 60 degrees. If they experience pain radiating down their leg, the test is considered positive, suggesting lumbar disk herniation. An MRI of the spine can confirm t