Patient history and physical examination are typically the first step in diagnosing pinched nerves. Types of symptoms, duration of symptoms, factors that improve/exacerbate symptoms, treatments that have been already tried, and past relevant medical problems/surgeries are all collected during the history. The physician completes a physical exam to check for specific symptoms by inspecting the back, assessing gait, and testing the upper and lower extremities for motor strength, reflexes, and range of motion.
Both history and physical exam contribute to the diagnosis of a pinched nerve, but imaging is necessary to finalize the diagnosis. X-rays are typically obtained first to look at the overall alignment of the spine and to check for spinal abnormalities such as scoliosis (curve in the spine), that may affect viable treatment options. These 2D results are supplemented with advanced imaging tests such as MRI or CT scans because these show a 3D view of the spine. MRI scans which show soft tissues, such as nerves and discs, are generally preferred over CT scans which show bony elements. Advanced imaging can show exactly which nerve or nerves are being pinched and what is causing the nerve to be pinched. Together history, physical exam, and imaging are all necessary in order to make a correct diagnosis and design an optimal treatment plan for a pinched nerve.
Dermatomes are areas of the skin and musculature that a single nerve supplies motor and sensory function to. Based on the location and type of symptom (e.g. radiating or shooting pain, numbness, tingling, or loss of muscle strength) knowledge of dermatomes can help identify which spinal nerve may be affected by a pinched nerve. However, each person is anatomically unique so this is used more as a guide than as a definite diagnostic technique.
Cervical Pinched Nerve (Neck)
Physical exam results that imply a cervical pinched nerve include decreased range of motion in the neck with difficulty moving the chin toward the chest, leaning the head back, or turning left and right as if checking a blind spot while driving. Motor strength testing would be performed on both the upper and lower extremities because weakness in certain muscle groups could imply a pinched nerve at the cervical level where the relevant nerve branches off of the spinal cord. For example, weakness in the deltoid muscle while raising your arms from your sides could indicate a pinched at the C4-5 level. Increases or decreases in the bicep, brachioradialis, or tricep muscle reflexes are commonly used to test for spinal pinched nerve and can potentially identify the affected spinal level because they are connected to the C5, C6, and C7 nerve roots respectively. Other tests include checking for changes in sensation and a heel to toe walk to evaluate balance.
Thoracic Pinched Nerve (Mid Back)
Physical exams checking for a thoracic pinched nerve will be much less involved than those looking for cervical and lumbar pinched nerves. The exam typically begins with examining the back for an abnormal curve, uneven muscles, or skin changes such as bruising. After inspection, the doctor will perform palpations over the muscles and center of the back. The legs would be tested for motor strength to ensure that both legs are at full strength and functioning normally. Lastly the physician may check for changes in sensation from one side of the body to the other.
Lumbar Pinched Nerve (Lower Back)
Physical exam abnormalities for the lumbar spine tend to occur exclusively in the lower body. As with evaluating the cervical and thoracic spine, it is important to start by looking at the back for changes in the skin, decreases in muscle size, or unevenness from one side of the back to the other. The next step would be palpation of the muscles and center of the back. Lumbar spine range of motion is tested with flexion, such as touching toes, and extension, leaning back at the waist to look for decreased motion due to pain. Motor strength testing would be performed on the lower extremities because weakness in certain muscle groups could imply a pinched nerve at the lumbar level where the relevant nerve branches from the spinal cord. For example, a pinched nerve at L3-4 or L4-5 levels may cause weakness with knee extension or straightening the leg. Changes in sensation may also be tested throughout the leg to check for areas with decreased sensation throughout or relative to the opposite leg. Increases or decreases in the patellar and Achilles reflexes are commonly used to test for spinal pinched nerve and can potentially identify the affected spinal level because they are connected to the L3/L4 and S1 nerve roots respectively. Other exam results that imply lumbar pinched nerves are abnormal walking patterns, including inability to walk on the heels and the toes.
