(If you have setup another prefix)
rm -rf .npm-global
sudo rm -rf /usr/local/lib/node_modules
sudo rm -rf ~/.npm
brew uninstall node --ignore-dependencies node
rm -rf /usr/local/lib/node_modules
Install node (includes npm) from the nodejs website
sudo chown -R $(whoami) $(npm config get prefix)/{lib/node_modules,bin,share}
Having the same issue! However, brew is giving me the following error: