Hoffmann Sign: Red Flag for Cervical Myelopathy
The Hoffmann sign is used by examiners assessing patients with symptoms of myelopathy (spinal cord compression). The test is done by quickly snapping or flicking the patient's middle fingernail. The test is positive for spinal cord compression when the tip of the index finger, ring finger, and/or thumb suddenly flex in response.
But what we don't know is if a positive sign correlates with the severity of the compression. Is it a better indicator of cervical (neck) myelopathy than some of the other signs such as the Babinski sign. A positive Babinski sign is seen as downward flexion of the big toe and fanning outward of the toes when quick pressure is applied to the bottom of the foot from the heel to the toes.
To answer these and other questions, two groups of neurologic patients were studied. The first group had decompressive surgery for cervical myelopathy. Decompressive procedures remove whatever is pressing on the spinal cord. This could be a thickened ligament, herniated disc, or bone spurs.
The second group came to the clinic because of low back and/or leg pain. They didn't have any neck apparent problems. Patients in this group were tested using the Hoffmann test. Anyone who had a positive Hoffmann's sign then had an MRI taken of the cervical spine. The MRI was reviewed for any signs of cord compression.
Both groups were also tested using the modified Japanese Orthopaedic Association (mJOA) scale score. This is a measure of severity of cervical myelopathy based on function. Points are given for ability to eat, walk, and bathroom without difficulty.
Results showed a positive Hoffman sign in 68 per cent of the patients in group one (the surgical group). Only 33 per cent of the same group had a positive Babinski sign. Function measured by the mJOA was higher in patients with a positive Hoffmann sign (compared with patients who had a positive Babinski sign).
Some patients (12 per cent) in group two had a positive Hoffmann sign. In some cases (25 patients) it was unilateral (present only on one side). Less often (11 patients), there was a bilateral Hoffmann sign (present on both sides).
The presence of a positive Hoffmann's sign in this group may point to the fact that the patient has spinal stenosis. In spinal stenosis, there is a narrowing of the spinal canal, which surrounds the spinal cord. Anything that narrows this space can put pressure on the spinal cord causing myelopathy. Patients with lumbar pain from stenosis often have similar changes in the upper spine that have not been identified yet.
The authors report these results show that the Hoffmann sign is more likely to be positive in patients with less severe neurologic involvement. It is also present more often in patients with cervical myelopathy than the Babinski sign. Bilateral Hoffmann sign in patients with low back pain was strongly linked with unknown compression of the cervical cord.
Therefore the Hoffmann sign is a reliable way to test for early signs of cervical myelopathy. The presence of Hoffmann sign on both sides strongly suggests the presence of spinal cord compression in the cervical spine. This is very helpful information when assessing patients with very few other objective findings.
However, the test is not foolproof because patients who don't have cervical myelopathy can have a positive Hoffmann sign. A positive Hoffmann sign can be observed in patients with hyperthyroidism, anxiety disorders, and other problems that involve increased deep tendon reflexes.
Sometimes patients with true cervical myelopathy don't have a positive Hoffman's sign. Although less reliable early on, when the Babinski test is positive, there is almost always a real neurologic problem.
The authors suggest performing the Hoffmann test on patients with low back and/or leg pain, especially when lumbar spinal stenosis is present. A positive sign on both sides warrants imaging of the cervical spine. Anyone with evidence of cervical cord compression but no outward symptoms should be followed regularly. Routine neurologic exams every six months are advised.
John K. Houten, MD, and Louis A. Noce, MD Clinical Correlations of Cervical Myelopathy and the Hoffman Sign. In Journal of Neurosurgery: Spine. September 2008. Vol. 9. No. 3. Pp. 237-242.