Neurological Glossary

Neurological terms are often complicated and difficult to understand. The following glossary defines a variety of terms to help you understand neurological terminology:

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    Saccular aneurysm

    Spherical outpouching from one side of an artery that occurs at an arterial bifurcation point and reflects weakness of all layers of the vessel wall


      Silicone Ankle Foot Orthosis


        Vertical plane passing through the standing body from front to back

          Sagittal sulcus (longitudinal fissure)


            Salivatory nuclei

            Small nuclei in the pontine tegmentum that provide parasympathetic preganglionic innervation to ganglia associated with the lacrimal and salivary glands to control salivation and tearing

              Saving Reaction

              Physical ability to save oneself when balance is lost

                Scanning speech (ataxic dysarthria)

                Abnormal staccato-like speech due to a lesion of the cerebellum or cerebellar pathways

                  Scaphocephaly (dolichocephaly)

                  Premature closure of the sagittal suture


                    Developmental birth defect characterized by abnormal slits or clefts in the cerebral hemispheres extending from the cortical surface to the underlying ventricle

                      Schwann cell

                      Glial cell of the PNS that forms the insulating myelin sheath of peripheral axons


                        WHO grade I benign peripheral nerve sheath tumour occurring commonly in the cerebellopontine angle (cranial nerve VII) or in the bony foramina around the spinal cord (spinal nerve root); characterized histologically by Antoni A and Antoni B tissue and Verocay bodies (zones of nuclear palisading)

                          Scintillating scotoma

                          Visual migraine aura consisting of shimmering lights followed by a dark spot or partial loss of vision that may move across the visual field


                            An abnormal sideways curvature/twist of the spine


                              Island-like gap or blind spot in the visual field

                                Secondary progressive

                                Clinical course of multiple sclerosis that initially is relapsing-remitting and then becomes progressive at a variable rate

                                  Secondary symptoms

                                  Symptoms referable to secondary effects of a lesion e.g.


                                    Discrete event due to sudden

                                      Selective Dorsal Rhizotomy

                                      A neurosurgical technique used in the treatment of spasticity in the lower limbs

                                        Sella turcica

                                        Saddlelike prominence on the upper surface of the sphenoid bone of the skull


                                          Referring to part of nervous system which receives and interprets signals through senses

                                            Sensory trick

                                            Specific trigger a patient uses to relieve dystonia

                                              Septal nuclei

                                              Neuronal structures in the rostral forebrain adjacent to the septum pellucidum that communicate with the hippocampus

                                                Septum pellucidum

                                                Membrane extending ventrally from the body of the corpus callosum that separates the two lateral ventricles from each other

                                                  Setting sun sign

                                                  Forced depression of the eyes due to pressure on the dorsal midbrain in the setting of hydrocephalus

                                                    Shadow plaque

                                                    Foci of myelin preservation at the periphery of active multiple sclerosis plaques thought to represent partial remyelination

                                                      Sharp wave

                                                      EEG pattern consisting of a transient electrical discharge with a pointed peak and a duration of 70-200 milliseconds that stands out from ongoing background activity; has a strong association with epilepsy

                                                        Shy-Drager syndrome

                                                        Older term for a variant of multisystems atrophy characterized by preferential degeneration of the intermediolateral cell column of the spinal cord and substantia nigra producing symmetric parkinsonism and autonomic failure


                                                          Drooling; increased salivation

                                                            Simple tic

                                                            Tic involving a limited number of muscles; simple vocal tics are meaningless noises such as grunting or throat clearing; simple motor tics are focal movements such as eye blinking or facial grimacing

                                                              Single fibre electromyography

                                                              Electrodiagnostic test in which potentials of muscle fibres innervated by a single axon are recorded; normal response is for fibres to be activated with consistent latencies whereas in neuromuscular junction disorders

                                                                Sjogren's syndrome

                                                                An autoimmune disorder that prohibits production of tears and saliva

                                                                  Skew deviation

                                                                  Hypertropia in which the eyes move vertically in opposite directions due to acquired supranuclear or vestibulo-ocular disruption

                                                                    Sleep latency

                                                                    Speed of falling asleep

                                                                      Sleep paralysis

                                                                      Temporary (seconds to minutes) inability to move or talk that occurs during sleep-to-wake or wake-to-sleep transitions; one of the symptoms of narcolepsy

                                                                        Slow wave sleep

                                                                        see non-REM sleep

                                                                          Smooth pursuit

                                                                          Smooth following eye movements that maintain fixation

                                                                            Solitary nucleus and tract

                                                                            Sensory nucleus of the medulla that receives afferent taste information from nerves VII


                                                                              Cell body

                                                                                Somatosensory evoked potentials (SSEP)

                                                                                Series of waves that reflect sequential activation of neural structures along the somatosensory pathways following electrical stimulation of peripheral nerves (typically elicited by stimulation of the median nerve at the wrist



                                                                                    Somnambulism (sleep walking)

                                                                                    Arising from bed during a period when there is a simultaneous occurrence of incomplete wakefulness and nonREM sleep; typically occurs in the first third of the night during deep sleep


                                                                                      Causing or tending to induce sleep


                                                                                        A term with two meanings:

                                                                                        • Popularly used to indicate any child or adult suffering from cerebral palsy and diplegia. This is detected by the particular sort of increased resistance to passive movement of the parts of the limb.
                                                                                        • Medically speaking it is used to describe a specific type of stiffness commonly seen in the limbs of hemiplegia.

                                                                                        Spastic Cerebral Palsy

                                                                                        The most common form of cerebral palsy where some muscles become very stiff and weak


                                                                                          The state of being spastic


                                                                                            Relationship of one thing to another in space

                                                                                              Spatial Perception

                                                                                              The appreciation of size

                                                                                                Spatial skills

                                                                                                Ability to judge depth


                                                                                                  Having both spatial extension and temporal duration

                                                                                                    Speech and Language Therapy

                                                                                                    Rehabilitation specialism directed to the treatment of people with speech and language difficulties

                                                                                                      Speech therapist / speech and language therapist (SALT)

                                                                                                      A therapist who specialises in the rehabilitation of people with speech and language difficulties

                                                                                                        Social worker (care manager)

                                                                                                        Professionally qualified employee of local Social Services Department who gives advice and practical help with social problems. They also assess the eligibility of a person for community care services.


                                                                                                          EEG pattern consisting of a transient electrical discharge with a pointed peak and a duration of less than 70 milliseconds that stands out from ongoing background activity; has a strong association with epilepsy

                                                                                                            Spike-and-wave complex

                                                                                                            Generalized synchronous pattern seen on electroencephalogram

                                                                                                              Spina bifida

                                                                                                              Failure of bone fusion in the posterior midline of the vertebral column resulting in a bony cleft through which the meninges and varying quantities of spinal cord tissue protrude

                                                                                                                Spina bifida occulta

                                                                                                                Closed spinal dysraphism characterized by posterior vertebral defect and various overlying cutaneous anomalies (e.g.

                                                                                                                  Spinal dysraphism

                                                                                                                  Failure of bone fusion in the posterior vertebral column; classified as open (not covered by skin) or closed (covered by skin)

                                                                                                                    Spinocerebellar ataxia

                                                                                                                    Group of hereditary neurodegenerative disorders caused by expansion of a CAG triplet repeat and characterized by progressive ataxia and variable other features such as neuropathy and hearing or visual loss

                                                                                                                      Spinal accessory nerve (cranial nerve XI)

                                                                                                                      Motor nerve originating partly from the medulla (nucleus ambiguus'innervating laryngeal muscles) and partly from the spinal cord (accessory nucleus in the ventral horn of the cervical cord'innervating the sternocleidomastoid and trapezius muslces); lesion results in weakness in turning the head to the opposite side and elevating the shoulder

                                                                                                                        Spinocerebellar tract

                                                                                                                        Fibre tract originating in the spinal cord and carrying proprioceptive input to the ipsilateral cerebellum

                                                                                                                          Spinothalamic tract

                                                                                                                          Axonal tract carrying information on pain and temperature that arises from the posterior nerve roots


                                                                                                                            Thickened posterior border of the corpus callosum


                                                                                                                              Interchangeable term with braces and orthoses. Used to support or correct upper and lower limbs


                                                                                                                                Degenerative disease of the vertebral column that can result in spinal cord compression

                                                                                                                                  Spongiform encephalopathy

                                                                                                                                  Progressive neurodegenerative disorder associated with various prion agents that produce spongy changes in the brain (e.g.

                                                                                                                                    Spreading cortical depression

                                                                                                                                    Brief wave of intense cortical activation followed by a marked decrease in neuronal activity and reduced blood flow that starts in the occipital cortex and spreads anteriorally at a rate of 2-6 mm/min; thought to underline migraine aura

                                                                                                                                      Standing Frame

                                                                                                                                      A piece of equipment to allow a child to be more upright allowing greater freedom of the trunk and arms.

                                                                                                                                        Status epilepticus

                                                                                                                                        Medical emergency defined as more than 30 minutes of either continuous seizure activity or two or more sequential seizures without full recovery of consciousness in between

                                                                                                                                          Status migrainosus

                                                                                                                                          Migraine attack that persists for > 72 hours and often leads to hospitalization


                                                                                                                                            Ability to recognize objects by touch


                                                                                                                                              Repetitive stereotyped movements commonly seen in tardive dyskinesia


                                                                                                                                                Symmetrical tonic neck reaction. Very rare and usually pathological in origin. When the legs are extended the flexor tone in the arms dominate. When the arms are extended the flexor tone in the legs dominate or vice versa for both patterns


                                                                                                                                                  Typical distribution on the body where symptoms/signs of peripheral neuropathy are evident (toes to knee and fingers to wrist)


                                                                                                                                                    misalignment of the eyes that is either developmental (due to a miscalibration of the binocular vergence system in the cerebral cortex at some point in infancy or childhood) or acquired (due to a palsy of a cranial nerve or extraocular muscle)

                                                                                                                                                      Stress incontinence

                                                                                                                                                      Partial loss of bladder control

                                                                                                                                                        Stria medullaris

                                                                                                                                                        White matter tract connecting the anterior hypothalamus and septal nuclei in the medial basal forebrain with the habenula

                                                                                                                                                          Stria terminalis

                                                                                                                                                          White matter tract containing amygdaloid efferents to the septal nuclei in the medial basal forebrain and nuclei of the anterior hypothalamus

                                                                                                                                                            Striate cortex

                                                                                                                                                            The part of the occipital lobe of the cerebral cortex that is the primary receptive area for vision

                                                                                                                                                              Striatonigral degeneration (SND)

                                                                                                                                                              Older term for a variant of multisystems atrophy characterized by degeneration of the striatum and the substantia nigra producing symmetric parkinsonism that does not respond to levodopa or dopamine agonists


                                                                                                                                                                Part of the basal ganglia consisting of the caudate and putamen separated by fibres of the anterior limb of the internal capsule


                                                                                                                                                                  Sudden loss of neurological function caused by a blockage or rupture of a blood vessel to the brain or spinal cord; includes infarction and haemorrhage subtypes

                                                                                                                                                                    Stroke unit

                                                                                                                                                                    Hospital facility for the effective management of patients with acute stroke by a multi-disciplinary team of specialists


                                                                                                                                                                      Condition of unresponsiveness from which the patient can only be aroused by vigorous and repeated stimuli; once stimulus ceases


                                                                                                                                                                        Developing over days to weeks; suggests an expanding lesion (e.g

                                                                                                                                                                          Subarachnoid haemorrhage

                                                                                                                                                                          Bleeding between the brain and one of the covering membranes

                                                                                                                                                                            Subarachnoid space

                                                                                                                                                                            Actual space separating the pia and arachnoid that surround the brain and spinal cord; contains cerebrospinal fluid

                                                                                                                                                                              Subclinical seizure

                                                                                                                                                                              Electrographic seizure without clinical manifestations


                                                                                                                                                                                Portion of the brain immediately below the cerebral cortex; includes corona radiata

                                                                                                                                                                                  Subcortical leukoencephalopathy

                                                                                                                                                                                  see Binswanger's disease

                                                                                                                                                                                    Subdural haemorrhage

                                                                                                                                                                                    Collection of blood in the subdural space following trauma to small bridging veins or in elderly patients with cerebral atrophy or those with clotting abnormalities

                                                                                                                                                                                      Subdural space

                                                                                                                                                                                      Potential space between the dura and arachnoid that can be filled with blood

                                                                                                                                                                                        Subhyaloid hemorrhage

                                                                                                                                                                                        Accumulation of blood near the optic disc seen on fundoscopic exam in subarachnoid haemorrhage


                                                                                                                                                                                          Division of the parahippocampal gyrus adjacent to the hippocampal fissure that is the major source of efferent fibres from the hippocampal formation to rostral structures in the basal forebrain


                                                                                                                                                                                            Tendency towards a joint shifting out of position

                                                                                                                                                                                              Substantia gelatinosa


                                                                                                                                                                                                Substantia nigra

                                                                                                                                                                                                Nucleus in the midbrain tegmentum that is divided into the pars compacta

                                                                                                                                                                                                  Subthalamic nucleus (subthalamus)

                                                                                                                                                                                                  Nucleus in the ventral diencephalon that modulates the output of the basal ganglia from the internal segment of the globus pallidus to the thalamus


                                                                                                                                                                                                    Groove in the cerebral cortex separating two gyri


                                                                                                                                                                                                      Nearer the head

                                                                                                                                                                                                        Superior cerebellar peduncle (brachium conjunctivum)

                                                                                                                                                                                                        Principle efferent fibre bundle from the cerebellum; fibres decussate in the midbrain and end primarily in the red nucleus and dorsal thalamus; lesions of the caudal SCP before the decussation result in ipsilateral deficits in motor coordination whereas lesions rostral to the decussation result in contralateral deficits; afferent fibers from the ventral spinocerebellar tract travel in the SCP to bring proprioceptive information from the lower body to the cerebellum

                                                                                                                                                                                                          Superior colliculus

                                                                                                                                                                                                          Paired structures on the dorsal surface of the rostral midbrain that receive unconscious visual input directly from the retina and help orient the head and eyes to all types of sensory stimuli

                                                                                                                                                                                                            Superior sagittal sinus

                                                                                                                                                                                                            Venous structure occupying the convex margin of the falx cerebri and draining the upper part of the cerebral hemispheres


                                                                                                                                                                                                              Lying on back


                                                                                                                                                                                                                Central connections rostral to the cranial nerve nuclei


                                                                                                                                                                                                                  above the sella turcica


                                                                                                                                                                                                                    Above the tentorium cerebelli


                                                                                                                                                                                                                      Junction between two bones of the skull: coronal separates the 2 frontal bones from the parietal bones; metopic separates the frontal bones; sagittal separates the 2 parietal bones; lambdoid separates the occipital bone from the 2 parietal bones

                                                                                                                                                                                                                        Sylvian fissure (lateral fissure or lateral sulcus)

                                                                                                                                                                                                                        Prominent long

                                                                                                                                                                                                                          Sympathetic nervous system

                                                                                                                                                                                                                          Part of the autonomic nervous system concerned with preparing the body for fear

                                                                                                                                                                                                                            Symptomatic epilepsy

                                                                                                                                                                                                                            Epilepsy that is due to a known cause (e.g.


                                                                                                                                                                                                                              Temporary loss of consciousness due to a lack of blood flow to the brain

                                                                                                                                                                                                                                Syndrome of inappropriate ADH secretion (SIADH)

                                                                                                                                                                                                                                Disorder of osmoregulation involving excessive release of arginine vasopressin (antidiuretic hormone)


                                                                                                                                                                                                                                  Condition associated with involuntary perceptual experiences that are elicited by stimuli that would not be expected to elicit such a response'a crossing of sensory modalities


                                                                                                                                                                                                                                    Group of neurodegenerative diseases characterized by neuronal or glial inclusions composed of alpha-synuclein; includes idiopathic Parkinson disease and diffuse Lewy body disease


                                                                                                                                                                                                                                      Central cavitation (cystic lesion) within the spinal cord (syringomyelia) that extends up to the medulla and pons


                                                                                                                                                                                                                                        Central cavitation (cystic lesion) of the spinal cord