What actually causes the symptoms of neuritis?

Neuritis not simple: An irritated nerve will produce symptoms of pain in the nerve area, and may cause weakness as well. Usually this term is used to specify a neurve related painful condition. However, sometimes the problem is in the brain and it only seems like it is in a nerve. Vestibular neuritis is a misnomer, the problem is usually in the inner ear. Brachial plexitis is also a neuritis.

Inflammation: Neuritis is a term for inflammation of nerves. The nerves involved may few and very localized or many and very diverse. The inflammatory reaction can be triggered by viral infection, toxic effects, autoimmune, or of unknown cause. Usually pain and dysesthesia occurs with resolution or permanent lose of function as neuropathy. Treatment depends on cause.