For the purposes of our guide, Northern Burma is comprised on Chin State to the west, bordering Bangladesh and India, Sagaing Division, also to the north and north west, bordering India and Kachin State to the remote far north bordering China and India. As with the southern coastal stretch of Burma, this region contains some of the most remote stretches of the country, some of which remain firmly off limits and (at least for now) out of the reach of casual travellers.
As with the rest of the country though, change is coming, and in 2013-2014 we were able to travel permit-less and without major hindrance up the Chindwin River in Sagaing Division and we heard reports of other travellers heading to both Khamti and Homilin in far northern Sagaing Division without problem and also to Myitkyina (Kachin State) without issue.
So the region is opening up, albeit somewhat unpredictably and haphazardly. When we were in Mawleik, for example, we were denied access to a crater lake (access is apparently now allowed) and we were also refused permission to cross the river -- but that didn't stop a luxury cruise from having a barbecue dinner on the far bank without problem!
Should you decide to head up this way, bring plenty of copies of your passport and visa and plenty of cash (don't expect ATMs). Expect a varying standard of accommodation -- generally mediocre, but habitable. Also expect to see very very few other foreign travellers.