Neurological Glossary
Habenula
Diencephalic structure located on the dorsomedial surface of the caudal thalamus that receives afferents from the septal nuclei and hypothalamus via the stria medullaris and projects to midbrain nuclei; involved in autonomic processing
Haematoma
A blood clot that has formed outside a blood vessel (artery or vein)
Haemorrhage
The escape of blood from a ruptured blood vessel, externally or internally
Haemorrhagic infarct
An area of dead brain that has had bleeding in it
Haemorrhagic stroke
A stroke caused by a burst blood vessel bleeding into the brain (intracerebral haemorrhage) or into the surrounding areas (subarachnoid haemorrhage)
HDL-C (High-Density Lipoprotein Cholesterol)
Also known as the "good" cholesterol: a compound consisting of a lipid and a protein that carries cholesterol in the blood and deposits it in the liver
HAFO
Hinged Ankle Foot Orthosis
Hangman’s fracture
Fracture through bilateral pedicles of C2 via various mechanisms; typically unstable
Hemianesthesia
Loss of somatosensation on one half of the body
Hemianopia
Loss of vision in one half of the visual field, indicating a pathological process posterior to the optic chiasm
Hemiballismus
Involuntary violent flinging or jerking of a limb (or limbs) in an uncoordinated manner caused by a lesion of the contralateral subthalamus in the brain
Hemicrania continua
Indomethacin-responsive headache disorder characterised by steady, moderately intense unilateral head pain on which are superimposed episodes of more intense pain with autonomic symptoms (eye tearing, eye redness, eyelid oedema, nasal congestion, runny nose) occurring several times a day
Hemifacial spasm
Segmental myoclonus of muscles innervated by the facial nerve; may be due to vascular compression of the facial nerve or facial nerve injury or tumour, or it may have no apparent cause
Hemifield
One-half of the binocular visual field
Hemiparesis
Weakness on one side of the body
Hemiplegia
Paralysis on one side of the body
Hemiplegic migraine
Familial form of migraine characterized by temporary (usually less than 1 hour but occasionally lasting up to a week) hemisensory symptoms often associated with visual aura and headache; in about 50% of affected families, a defect may be found on chromosome 19 or on chromosome 1 and involves abnormal calcium channels
Heterotopia
Tissue occurring in an abnormal anatomical position
Hindbrain
Medulla, Pons and Cerebellum
Hip dislocation
In children with spasticity the thigh bone [femur] can gradually be pulled out of its socket where it connects with the hip – this is treated surgically
Hippocampal formation
Cortical structure in the medial temporal lobe comprising the dentate gyrus, hippocampus, and subiculum; involved in short-term declarative memory
Hippocampus
Convoluted structure at the medial margin of the cortical mantle of the cerebral hemisphere, bordering the choroid fissure of the lateral ventricle, and forming part of the limbic system, which is concerned with memory and emotion
Hoffman’s sign
Contraction of fingers and thumb when a stimulus is applied to a distal phalanx in that hand; indication of hyperreflexia in the upper extremity
Holoprosencephaly
Failure of cleavage at the rostral end of the notochord resulting in midline fusion of the frontal lobes, midline facial abnormalities, and often hydrocephalus and heterotopias
Homer-Wright rosette
Halo of cells surrounding a central lumen containing neuropil; found in medulloblastomas and PNETs
Horner's syndrome
Ptosis, miosis, and anhidrosis ipsilateral to damaged sympathetic nerve fibres
H-reflex
Electrical equivalent of the monosynaptic stretch reflex elicited by selectively stimulating the fibres of the posterior tibial or median nerve
Hunt and Hess scale
Scale for grading clinical status in patients with nontraumatic subarachnoid hemorrhage that correlates well with clinical outcome Click here for more information from the Stroke Trials Registry
Huntington disease
Fatal autosomal dominant neurodegenerative disorder characterized by chorea and progressive dementia; due to a trinucleotide CAG-repeat mutation on chromosome 4
Hydranencephaly
Birth defect in which the majority of the cerebral hemispheres and striatum are absent and replaced by sacs filled with cerebrospinal fluid; considered to be an extreme form of porencephaly
Hydrocephalus
Meaning "water on the brain;"an increase in size of ventricles and amount of cerebrospinal fluid in the brain
Hyperacusis
Abnormally increased sensitivity to sound
Hyperbaric Oxygen Therapy
Oxygen therapy used in the treatment of a variety of conditions
Hyperkinesis
Incessant, restless activity
Hyperpathia
Exaggerated response to painful stimuli
Hypersomnolence
see excessive daytime sleepiness
Hypertensive hemorrhage
Intraparenchymal hemorrhage with a predilection to occur deep in the cerebral hemispheres, especially in the putamen, thalamus, and deep white matter, as well as the pons and cerebellum. These sites are all supplied by small penetrating arteries that are subject to high sheer stress and have no collaterals, making them vulnerable to the effects of increased blood pressure
Hypertonia
Too much muscle tone leading to stiffness
Hypertonicity
Increase in passive muscle resistance, such as spasticity or rigidity
Hypertropia
An eye with strabismus that deviates up
Hypnagogic hallucination
Vivid dreamlike hallucination that occurs as one is falling asleep; one of the symptoms of narcolepsy, but also experienced by some non-narcoleptic individuals
Hypnic headache
Indomethacin-responsive headache disorder characterized by diffuse, throbbing headache arising exclusively during sleep, typically between 1:00 and 3:00 AM
Hypnic
Jerk sensation of falling, and then "jerking" awake just as one drifts to sleep
Hypnopompic hallucination
Vivid dreamlike hallucination that occurs as one is waking up; one of the symptoms of narcolepsy, but also experienced by some non-narcoleptic individuals
Hypoglossal nerve (cranial nerve XII)
Motor nerve that innervates all tongue muscles except the palatoglossus; lesions result in deviation of the protruded tongue towards the paralyzed side and deviation of the tongue at rest away from the paralyzed side; nucleus is located in the medulla
Hypothalamus
Basal part of the diencephalon that controls hunger, thirst, body temperature, and various metabolic processes, including the maintaining of water balance
Hypotonia
Too little muscle tone leading to floppiness
Hypotonicity
Reduction in passive muscle resistance
Hypotropia
An eye with strabismus that deviates down
Hypoxia
Reduction in the supply of oxygen to the brain or other vital organ
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