I have the same issues. Mine were attributed to damage in my neck. (Whiplash is very common in head injuries.)

Did the neuro test your grip strength, check your finger wiggling speed, give you a peg board test to measure dexterity and/or do a nerve conductivity test? When your knees are tapped, do you kick like a chorus girl? You might want to advocate for an MRI of your neck.

In my case, the damage was deemed too dangerous to address surgically, so I just have to live with it. I had occupational therapy and have a lot of useful aides, like oversized pens and cooking utensils. Thanks to therapy, I also regained the ability to button (slowly) a shirt and tie my own shoes. I still can't cross my fingers. That must explain my bum luck.

That said, as the swelling subsided in my neck, the pressure came off the nerves and some things improved. However, I still tingle (pretty much everywhere) and have very little strength and mobility in my hands. I also have moments where my hand will just fly open. It always seems to happen when I'm holding something hot, sure to stain or fragile.