A neurologist is a doctor who is an expert in the diagnosis, treatment, and management of problems that affect the nervous system. They treat disorders, illnesses, and injuries of both the central (the brain and the spinal cord) and the peripheral nervous system.

Though a neurologist and neurosurgeon diagnose and treat disorders of the nervous system, a neurologist cannot perform surgery. Hence, if a patient requires surgical treatment for a neurological condition such as tumours or carpal tunnel syndrome, then a neurologist would refer the patient to a neurosurgeon.

Some illnesses that the neurologist treats are:
Neurodegenerative disorders such as Alzheimer's disease, Parkinson's disease
Epilepsy
Headaches
Back pain
Brain tumour
Multiple sclerosis
Injury or infection that affects the brain or spinal cord
Peripheral neuropathy (a condition that affects your nerves)
Pinched nerves
Stroke
Tremors

You should visit a neurologist if you have:
Headaches
Numbness or tingling sensation
Chronic pain
Loss of bladder or bowel function
Excessive weakness
Difficulty in walking
Jerky movements
Tremors
Confusion
Problems with memory
Difficulty in sleeping
Changes in vision
Seizures

Neurologists usually work with neurosurgeons, whereby they plan surgeries if required for the improvement in the condition of a patient. A neurologist may also teach and conduct research to contribute to the scientific knowledge in neurology.