Call our Helpline: 0808 808 1000

A to Z of neurological topics

In this section we feature information on a number of tests, treatments and conditions, with links for more information either within this website or on external sites where possible. If you can't find what you're looking for, you may wish to speak with one of our Helpline team who may be able to answer your questions. Send an email to [email protected] or call free on 0808 808 1000.

  • D

    Decompression surgery


    A type of surgery that is directed at reducing or relieving pressure, often achieved by removing a piece of bone. It is sometimes used to treat Chiari malformations by removing a small section of bone at the base of the skull. Decompression surgery is also used to treat nerves that are compressed in and around the spine, and this involves removing a segment of bone from a vertebra.

    Deep vein thrombosis (DVT)


    A blood clot, also known as a thrombosis, which develops within a deep vein in the body. This blood clot can travel from where it formed and sometimes block smaller blood vessels, for instance in the brain (causing a stroke) or lungs (causing a pulmonary embolism).

    Delayed cerebral ischaemia


    Delayed cerebral ischaemia occurs when there is a dangerously low supply of blood to the brain, causing brain damage. It can be due to spasm of the blood vessels (vasospasm) in the head, and can follow a few days after a subarachnoid haermorrhage.



    An umbrella term for a range of progressive neurological disorders that affect the brain and can cause problems with brain functions such as memory, language, and problem-solving.


    Useful links:

    Dementia Research Centre

    Dementia services in London

    Dementia UK

    Devic's disease


    See Neuromyelitis optica for more information



    A medical term for double vision, which is when you look at one object but see two images of it.

    Dizziness and balance problems


    See our Dizziness and balance problems booklet


    (also called the dura mater)


    A thin covering that surrounds your brain and spine. The dura mater is one of three layers known together as the meninges. It is tough compared to the other two layers, the pia mater and the arachnoid mater, and is the outermost layer, lying closest to the skull.



    Dyskinesia is an abnormal, uncontrolled movement that a person does not intend to perform. These movements can be repetitive motions or more like spasms.



    A medical term for problems with swallowing.



    A medical term for a range of movement disorders that cause uncontrollable muscle spasms and contractions. These contractions can result in slow, repetitive movements or unusual postures that can be painful.


    Useful links:

    The Dystonia Society