honeypot link
skip to main content
  • follow us on facebook
  • follow us on X
MSD Manual LogoMSD ManualConsumer Version
HEALTH TOPICSHEALTHY LIVINGSYMPTOMSEMERGENCIESRESOURCESCOMMENTARYABOUT US
homeHEALTH TOPICSHEALTHY LIVING
Search icon
  1. <Quick facts
    Quick Facts: Brain, Spinal Cord, and Nerve Disorders
    Cranial Nerve Disorders
    • Bell Palsy
      • What is Bell palsy?
      • What causes Bell palsy?
      • What are the symptoms of Bell palsy?
      • How can doctors tell if I have Bell palsy?
      • How do doctors treat Bell palsy?
    Dementia
    • Dementia
      • What is dementia?
      • What causes dementia?
      • What are the symptoms of dementia?
      • How can doctors tell if someone has dementia?
      • How do doctors treat dementia?
        • Care for caregivers
    • Alzheimer Disease
      • What is Alzheimer disease?
      • What causes Alzheimer disease?
      • What are the symptoms of Alzheimer disease?
      • How can doctors tell if someone has Alzheimer disease?
      • How do doctors treat Alzheimer disease?
        • Care for caregivers
      • How can I prevent Alzheimer disease?
    • Chronic Traumatic Encephalopathy (CTE)
      • What is chronic traumatic encephalopathy (CTE)?
      • What causes CTE?
      • What are the symptoms of CTE?
      • How can doctors tell if I have CTE?
      • How do doctors treat CTE?
        • Care for caregivers
    Headaches
    • Migraines
      • What are migraines?
      • What causes migraines?
        • What triggers migraines?
      • What are the symptoms of migraines?
        • Warning symptoms of migraine
      • How can doctors tell if I have migraines?
      • How do doctors treat migraines?
      • How can I prevent migraines?
    • Tension-Type Headaches
      • What are tension-type headaches?
      • What causes tension-type headaches?
      • What are the symptoms of tension-type headaches?
      • How can doctors tell if I have tension-type headaches?
      • How do doctors treat tension-type headaches?
    • Overview of Headaches
      • What causes a headache?
      • When should I see a doctor for a headache?
      • What will happen at my doctor visit?
      • How do doctors treat headaches?
    • Cluster Headaches
      • What is a cluster headache?
      • What causes a cluster headache?
      • What are the symptoms of a cluster headache?
      • How can doctors tell if I have a cluster headache?
      • How do doctors treat cluster headaches?
    Stroke (CVA)
    • Stroke
      • What is a stroke?
      • What causes a stroke?
        • What are the risk factors for having a stroke?
      • What are the symptoms of a stroke?
      • What are the long-term problems after a stroke?
      • How will my doctor know if I had a stroke?
      • How do doctors treat a stroke?
        • In the hospital
        • After you leave the hospital
      • Can you recover after a stroke?
    • Transient Ischemic Attacks (TIA)
      • What is a transient ischemic attack (TIA)?
      • What causes a TIA?
      • What are the symptoms of a TIA?
      • How will my doctor know if I had a TIA?
      • How do doctors treat a TIA?
    • Intracerebral Hemorrhage
      • What is an intracerebral hemorrhage?
      • What causes an intracerebral hemorrhage?
      • What are the symptoms of an intracerebral hemorrhage?
      • How will my doctor know if I had an intracerebral hemorrhage?
      • How do doctors treat an intracerebral hemorrhage?
    • Subarachnoid Hemorrhage
      • What is a subarachnoid hemorrhage?
      • What causes a subarachnoid hemorrhage?
      • What are the symptoms of a subarachnoid hemorrhage?
      • How will my doctor know if I had a subarachnoid hemorrhage?
      • How do doctors treat a subarachnoid hemorrhage?
    Movement Disorders
    • Parkinson Disease (PD)
      • What is Parkinson disease?
      • What causes Parkinson disease?
      • What are the symptoms of Parkinson disease?
      • How can doctors tell if I have Parkinson disease?
      • How do doctors treat Parkinson disease?
        • Caregiver and end-of-life issues
      • Where can I get more information about Parkinson disease?
    • Tremor
      • What is a tremor?
      • When should I see a doctor?
      • What causes a tremor?
      • What will happen at my doctor visit?
      • What tests will I need?
      • How do doctors treat a tremor?
    • Dystonia
      • What is dystonia?
      • What causes dystonia?
      • What are the symptoms of dystonia?
      • How can doctors tell if I have dystonia?
      • How do doctors treat dystonia?
    • Huntington Disease
      • What is Huntington disease?
      • What causes Huntington disease?
      • What are the symptoms of Huntington disease?
      • How can doctors tell if I have Huntington disease?
      • How do doctors treat Huntington disease?
    • Parkinsonism
      • What is parkinsonism?
      • What causes parkinsonism?
      • What are the symptoms of parkinsonism?
      • How can doctors tell if I have parkinsonism?
      • How do doctors treat parkinsonism?
    Seizure Disorders
    • Seizure Disorders
      • What is a seizure disorder?
      • What is epilepsy?
      • What causes a seizure disorder?
      • What happens during a seizure?
      • What will doctors do after I have a seizure?
      • How do doctors treat seizure disorders?
      • What should I do if someone is having a seizure?
    Symptoms of Brain, Spinal Cord, and Nerve Disorders
    • Memory Loss
      • What is memory loss?
      • When should I see a doctor for memory loss?
      • What causes memory loss?
      • What will happen at my doctor visit?
      • How do doctors treat memory loss?
      • What can I do to help cope with memory loss?
    • Muscle Cramps
      • What are muscle cramps?
      • What causes muscle cramps?
      • When should I see a doctor for muscle cramps?
      • What will happen at my doctor visit?
      • How do doctors treat muscle cramps?
      • How can I prevent muscle cramps?
    • Weakness
      • What is weakness?
      • When should I see a doctor?
      • What causes weakness?
      • What will happen at my doctor visit?
      • How do doctors treat weakness?
    • Numbness
      • What is numbness?
      • When should I see a doctor for numbness?
      • What causes numbness?
      • What will happen at my doctor visit?
      • How do doctors treat numbness?
    Meningitis
    • Bacterial Meningitis
      • What is bacterial meningitis?
      • What causes bacterial meningitis?
        • What raises my risk of getting bacterial meningitis?
      • What are the symptoms of bacterial meningitis?
        • Symptoms of meningitis in infants and babies
        • Symptoms of meningitis in older children and adults
        • What are the complications of bacterial meningitis?
      • How can doctors tell if I have bacterial meningitis?
      • How do doctors treat bacterial meningitis?
      • How can I prevent acute bacterial meningitis?
    • Viral Meningitis
      • What is viral meningitis?
      • What causes viral meningitis?
      • What are the symptoms of viral meningitis?
      • How can doctors tell if I have viral meningitis?
      • How do doctors treat viral meningitis?
    Multiple Sclerosis (MS) and Related Disorders
    • Multiple Sclerosis (MS)
      • What is multiple sclerosis (MS)?
      • What causes MS?
      • What are the symptoms of MS?
      • How can doctors tell if I have MS?
      • How do doctors treat MS?
      • Where can I find more information on MS?
    Sleep Disorders
    • Snoring
      • What is snoring?
      • When should I see a doctor about my snoring?
      • What causes snoring?
      • What will happen at my doctor's visit?
      • How do doctors treat snoring?
    • Insomnia and Excessive Daytime Sleepiness (EDS)
      • What are insomnia and excessive daytime sleepiness?
      • What causes insomnia or excessive daytime sleepiness?
      • What are the symptoms of insomnia and EDS?
      • When should I see a doctor for a sleep problem?
      • How can doctors tell if I have insomnia or EDS?
        • What are sleep tests?
      • How do doctors treat insomnia and EDS?
    • Narcolepsy
      • What is narcolepsy?
      • What causes narcolepsy?
      • What are the symptoms of narcolepsy?
      • How can doctors tell if I have narcolepsy?
        • What are sleep tests?
      • How do doctors treat narcolepsy?
    Peripheral Nerve Disorders
    • Amyotrophic Lateral Sclerosis (ALS)
      • What is ALS?
      • What are the symptoms of ALS?
      • How can doctors tell if I have ALS?
      • How do doctors treat ALS?
    • Myasthenia Gravis
      • What is myasthenia gravis?
      • What causes myasthenia gravis?
      • What are the symptoms of myasthenia gravis?
        • What is myasthenic crisis?
      • How can doctors tell if I have myasthenia gravis?
      • How do doctors treat myasthenia gravis?
    • Guillain-Barré Syndrome (GBS)
      • What is GBS?
      • What causes GBS?
      • What are the symptoms of GBS?
      • How can doctors tell if I have GBS?
      • How do doctors treat GBS?
    Spinal Cord Disorders
    • Spinal Cord Compression
      • What is spinal cord compression?
      • What causes spinal cord compression?
      • What are the symptoms of spinal cord compression?
      • How can doctors tell if I have spinal cord compression?
      • How do doctors treat spinal cord compression?
    • Overview of Spinal Cord Disorders
      • What is your spine?
      • What is your spinal cord?
      • What are spinal nerves?
      • What are spine and spinal cord disorders?
        • Spine disorders
        • Spinal cord disorders
      • What causes a spinal cord disorder?
      • What are the symptoms of a spinal cord disorder?
      • How can doctors tell if I have a spinal cord disorder?
      • How do doctors treat spinal cord disorders?
    Diagnosis of Brain, Spinal Cord, and Nerve Disorders
    • Spinal Tap
      • What is a spinal tap?
      • Why would I need a spinal tap?
      • What happens during a spinal tap?
      • What are the problems with a spinal tap?
    • Electroencephalography (EEG)
      • What is an EEG?
      • Why would I need an EEG?
      • What happens during an EEG?
      • What are the problems with an EEG?
    • Electromyography (EMG) and Nerve Conduction Studies
      • What are EMG and nerve conduction studies?
      • Why would I need an EMG or nerve conduction study?
      • What happens during an EMG or nerve conduction study?
      • What are the problems with an EMG or nerve conduction study?
    Brain Infections
    • Brain Abscess
      • What is a brain abscess?
      • What causes a brain abscess?
      • What are the symptoms of a brain abscess?
      • How can doctors tell if I have a brain abscess?
      • How do doctors treat a brain abscess?
    • Encephalitis
      • What is encephalitis?
      • What causes encephalitis?
      • What are the symptoms of encephalitis?
      • How can doctors tell if I have encephalitis?
      • How do doctors treat encephalitis?
    • Rabies
      • What is rabies?
      • What causes rabies?
      • What are the symptoms of rabies?
      • How can doctors tell if I have rabies?
      • How do doctors treat rabies?
      • How can I prevent rabies?
    • Overview of Brain Infections
      • How do infections get in your brain?
      • What are the symptoms of a brain infection?
      • How do doctors diagnose brain infections?
      • How do doctors treat brain infections?
    Coma and Impaired Consciousness
    • Stupor and Coma
      • What is stupor?
      • What is a coma?
      • What causes stupor or coma?
      • What are the symptoms of stupor or coma?
      • How can doctors tell if a person is in a stupor or coma?
      • How do doctors treat stupor and coma?
    • Vegetative State
      • What is a vegetative state?
      • What causes a vegetative state?
      • What are the symptoms of a vegetative state?
      • How can doctors tell if someone is in a vegetative state?
      • How do doctors treat someone in a vegetative state?
    • Brain Death
      • What is brain death?
      • What causes brain death?
      • How can doctors tell if someone is brain dead?
      • What do doctors do if someone is brain dead?
    Tumors of the Nervous System
    • Overview of Brain Tumors
      • What is a brain tumor?
      • What are the symptoms of brain tumors?
      • How can doctors tell if I have a brain tumor?
      • How do doctors treat a brain tumor?
        • End-of-life issues
    Pain
    • Overview of Pain
      • What causes pain?
      • How do doctors treat pain?
        • What pain treatments don't involve medicines?
      • What are opioids?
        • What are the side effects of opioids?
        • Will I get addicted to opioids?
      • What are NSAIDs (nonsteroidal anti-inflammatory drugs)?
        • What are the side effects of NSAIDs?
      • What are other pain medicines?
    • Neuropathic Pain
      • What is neuropathic pain?
      • What causes neuropathic pain?
      • What are the symptoms of neuropathic pain?
      • How can doctors tell if I have neuropathic pain?
      • How do doctors treat neuropathic pain?
    • Chronic Pain
      • What is chronic pain?
      • What causes chronic pain?
      • What are the symptoms of chronic pain?
      • How do doctors treat chronic pain?
        • Pain medicine
    Biology of the Nervous System
    • Overview of the Nervous System
      • What is the nervous system?
      • How does your nervous system work?
      • What can go wrong with your nervous system?
      • How does age affect the nervous system?
    • The Brain
      • What is the brain?
        • What are the parts of the brain?
      • How does the brain work?
      • What can go wrong with the brain?
    • The Spinal Cord
      • What is the spinal cord?
      • How does the spinal cord work?
        • What are spinal nerves?
      • What can go wrong with the spinal cord?
    • The Nerves
      • What are nerves?
      • How do nerves work?
      • What can go wrong with nerves?
    MSD
    • About
    • Disclaimer
    • Permissions
    • Privacy
    • Cookie Preferences
    • Terms of use
    • Partnerships
    • Contact Us
    • Global Medical Knowledge
    • Veterinary Manual
    • Mobile App
    • follow us on facebook
    • follow us on X
    This icon serves as a link to download the eSSENTIAL Accessibility assistive technology app for individuals with physical disabilities. It is featured as part of our commitment to diversity and inclusion.
    • follow us on facebook
    • follow us on X
    This icon serves as a link to download the eSSENTIAL Accessibility assistive technology app for individuals with physical disabilities. It is featured as part of our commitment to diversity and inclusion.
    MSD

    Copyright© 2026Merck & Co., Inc., Rahway, NJ, USA and its affiliates. All rights reserved.