What is the hoffman or huffman sign? It is a neurology sign to do with MS lesions?

Nonspecific. Hoffman's is a finger flick reflex response and may be seen unilaterally after a focal brain lesion. It has nothing to do with the diagnosis of ms and is merely part of a neurological examination. Granted some ms pts do show this sign, but in my experience it is of no value in correlating any diagnosis without additional signs.