The German neurologist Johann Hoffman first postulated this sign.  It was described by his assistant Hans Curschmann in 1911 and has become a standard part of the common neurologic exam.[1] The Hoffman sign is an involuntary flexion movement of the thumb and or index finger when the examiner flicks the fingernail of the middle finger down. The reflexive pathway causes the thumb to flex and adduct quickly.  A positive Hoffman sign can be indicative of an upper motor neuron lesion and corticospinal pathway dysfunction likely due to cervical cord compression. However, up to 3% of the population has been found to have a positive Hoffman without cord compression or upper motor neuron disease. 

While the Hoffman sign can help as a screening tool, it is not reliable as a stand-alone predictor of spinal cord compression. Degenerative cervical myelopathy is a spinal cord dysfunction that can lead to numbness, pain, imbalance, sensory loss, hyperreflexia, and urinary incontinence. Estimates are that nearly 1.6 per 100000 have had surgical treatment for cervical myelopathy.[2] During a standard neurological exam, Hoffman sign is common, and a positive sign can aid in the diagnosis.  However, a 2018 systematic review, with level 1 evidence, on the utility of the Hoffman sign for the diagnosis of degenerative cervical myelopathy found that there was insufficient data to support the use of the exam alone to confirm or refute a diagnosis of degenerative cervical myelopathy.[3] While the Hoffman sign can help as a screening tool, clinicians cannot rely on it as a stand-alone predictor of spinal cord compression.

The gold standard for diagnosing cervical myelopathy is an MRI. A 2015 study found that positive cord signal changes seen on MRI correlate with 67% of those with Hoffman sign.[4] The Hoffman sign is not always indicative of pathological cord compression.  But when it is present with corresponding MRI images, it was shown that if the compression of the cervical cord was higher in the canal, it correlated with a higher incidence of a positive Hoffman sign.[1]