Hewitt played 23 times for the All Blacks, including nine Tests, after he was first selected as an understudy to Sean Fitzpatrick for the 1993 series against the British and Irish Lions.
In 1997, Hewitt had an intense face-to-face showdown with England's Richard Cockerill during the haka before a match at Old Trafford.
Hewitt later described the incident, which ended with pushing and shoving between the pair, as an ingrained part of "rugby folklore".
Researchers have found that professional rugby players are as much as 15 times more likely to develop motor neurone disease.
English rugby league player Rob Burrow died earlier this year aged 41 after a four-year battle with the rare, degenerative illness.
"I played against Norm as a young player, and he was uncompromising on the field but always gracious with his time off it," New Zealand Rugby chief executive Mark Robinson said.
Off the field, Hewitt made headlines in 1999 when he drunkenly broke into the wrong hotel room.
It proved to be a life-changing incident as it made Hewitt realise he had to deal with his drinking problem and led him to become a youth mentor.
His name was immortalised in the television comedy series "Flight of the Conchords" starring Jemaine Clement and Bret McKenzie.
Clement said the character Murray Hewitt - played by Rhys Darby - came from a combination of the names "of two famous New Zealand rugby players: Murray Mexted and Norm Hewitt."
