Bragard’s Sign Test – Uses, Procedure, Technique

Clinical Examination

All participants were referred by physicians other than those who performed the study. One physical medicine and rehabilitation? specialist blinded to all outcome data visited all eligible participants and performed the physical examinations. The standardized clinical examination consisted of L5, S1 dermatomal sensory testing through softly striking the skin bilaterally and simultaneously. The patient, with eyes closed, was asked if the feeling clearly differed between the left and right sides, L5, S1 myotomal muscle strength (by testing muscle strength during big toe extension and ankle plantarflexion in supine position against resistance compared with nonsymptomatic side), and determination of Achilles stretch reflexes (noticing reflex diminution or abolishment) and muscle wasting (by measuring calf circumference and providing 1 cm difference with nonsymptomatic side for a positive test result). There were intervals of 5 minutes’ rest between diagnostic tests to allow the patients to recover from any pain or discomfort induced during the examination. The order of test performance (SLR or Modified Bragard test) was also randomly alternated to prevent testing bias.

Assessment? Procedures

The SLR test was performed by having the patient lie down on a flat examination table in a supine position. Both hips and knees of the involved leg were maintained in a neutral position neither abducted nor adducted. The patient’s head was not supported by a pillow. The examiner grasped the patient’s heel in the cup of his hand. The examiner’s other hand maintained the patient’s knee in an extended position. The examiner slowly raised the tested leg up to 90° by flexing the hip while maintaining the knee in extension and keeping the limb neutral, neither externally nor internally rotated. The maneuver was positive if the patient complained of reproduction of symptoms distal to the knee joint, between 30° and 70° of hip flexion.^[rx] An angular goniometer with a degree of error equal to ±1° was applied at the level of the greater trochanter to measure the value of hip flexion.

When a structural abnormality? such as a herniated disk compresses the nerve root proximal to or at the neural foramen, pain may occur. This may lead to pain radiating down the leg in the appropriate nerve root distribution (generally L5, or S1). The exact cause of the pain is unknown, but the symptoms may be related to decreased blood flow in the nerve root, increased tension of the nerve, compression of the nerve root, nerve root irritation, or other causes.⁶ The reproduction of back pain? only or thigh pain (not extending distal to the knee) was considered a negative test.

The Modified Bragard test was performed in the following manner. The patient was positioned supine on the examination table with both legs straight. The examiner began with the SLR test. If the patient sensed no radicular pain or symptoms despite 70° hip flexion (negative SLR test), the foot was dorsiflexed firmly, and if radiating pain below the knee was produced, the Modified Bragard test result would be recorded as positive. The test is based on the hypothesis that combining hip flexion and knee extension with ankle dorsiflexion will increase the examiner’s capacity to provoke nerve root/sciatic signs and symptoms in SLR-negative patients.

Electrodiagnosis (EDx) served as the reference criterion for lumbosacral radiculopathy. All the eligible participants underwent the same standardized electrophysiologic examination by a board-certified physiatrist with 10 years of postgraduate experience by the same instrument (Medelec Synergy VIASIS, Surrey, England) in the same session as physical examination was performed without any time interval. She was unaware of the patients’ physical examination at the time of enrollment.

The EDx was considered positive according to standardized diagnostic criteria: (A) positive sharp waves or fibrillation potentials (in 1-limb muscle plus lumbar paraspinal muscles at the corresponding level, or in 2-limb muscles innervated by the same nerve root), (B) remodeled motor unit action potentials (high-amplitude, long-duration or polyphasic motor unit action potentials increased more than 30% in at least 2 muscles of 1 myotome innervated by the same myotome but by separate peripheral nerves), or (C) prolonged soleus H reflexes.^[rx]

All nerve conduction study? procedures were performed in accordance with the guidelines for measurement, temperature, safety precautions, and electrode placement.^[rx] Motor and sensory nerve conduction studies were carried out first, and after that, H-reflex testing of the soleus and electromyography were conducted. The H reflex was used to evaluate the status of the peripheral nervous system with respect to proximal peripheral nerve conduction and potential entrapment of the nerve roots, such as radiculopathies. To perform soleus muscle H-reflex testing, the patient was positioned comfortably in a prone position with the feet off the edge of a plinth. A pillow was placed beneath the legs to cause slight knee flexion. The active electrode was located in the bisected line between the mid-popliteal fossa and the Achilles tendon?, and the reference electrode was located over the Achilles tendon? when the ground electrode was placed between the stimulus and recording electrode. A sweep speed of 10 ms/div, amplifier sensitivity of 500 μV/div, and pulse duration of 1.0 ms were used. The cathode of the stimulator was placed in the mid-popliteal fossa with the anode distal. The stimulus was delivered at a rate of 1 stimulation every 2 to 3 seconds. The current intensity was slowly increased until the H-reflex magnitude was maximized without concomitant activation of the motor fibers. Several responses were noted at this stimulus level to ensure a reproducible and stable response. The latency was then recorded to the initial departure of the H reflex from the baseline?. A side-to-side difference of 1.5 ms was used as a prediction of an S1 radiculopathy.^[rrx] H-reflex latency prolongation or side-to-side differences probably indicate neural demyelination with significant damage of the large-diameter nerve axons.^[rx]