Neuroanatomy and Neuroscience

at a Glance

Fourth EditionRoger A. Barker, Francesca Cicchetti, and Michael J. Neal

Medicine Glossary

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Acalculia inability to do simple calculations

Acoustic neuroma benign tumour originating from the Schwann cells of the vestibular component of the eighth cranial nerve

Acute disseminated encephalomyelitis monophasic illness that is thought to represent an immunological reaction to a component of central myelin in response to a systemic illness or vaccination. It causes widespread patchy demyelination in brain and spinal cord

Agraphia inability to write

Akinetic mutism describes a state of not moving or talking

Alexia inability to read

Allodynia perception of a non-noxious cutaneous stimulus as painful

Amblyopia poor visual acuity, usually in a strabismic eye

Amyotrophic Lateral Sclerosis a form of motorneuron disease in which there is both upper and lower motorneuron involvement

Anaesthesia absence of sensation (general anaesthesia refers to a state of drug-induced loss of consciousness)

Analgesia absence of a sense of pain

Anencephaly a developmental defect in which the brain fails to develop

Angelman's syndrome a rare inherited condition which presents with a typical appearance (happy puppet) with epilepsy

Anosmia loss of sense of smell

Anterior spinal artery syndrome spinal cord syndrome secondary to occlusion of the anterior spinal artery resulting in infarction of the anterior two-thirds of the spinal cord resulting in weakness, pain and temperature loss but with preservation of light touch and joint position sense

Anxiety disorder In anxiety disorders the patient experiences anxiety that is disproportionate to the stimulus, and sometimes in the absence of any obvious stimulus. There is no organic basis for anxiety disorders, the symptoms resulting from overactivity of the brain areas involved in 'normal' anxiety.

Aphagia an inability to swallow

Arteriovenous malformation (AVM) an abnormal collection of blood vessels, normally congenital which can increase in size during life. They may haemorrhage.

Asterognosis inability to recognise objects by touch

Astigmatism a disturbance of vision in which the refraction of the eye varies in different meridians

Astrocytoma a tumour of astrocytes

Ataxia inco-ordination due to damage to the cerebellum and/or the major sensory pathways conveying joint position sense

Autosomal dominant cerebellar ataxias there are a number of these disorders (named SCA) which present as a progressive cerebellar syndrome often with evidence of degeneration at other sites (e.g. retina). Many of these disorders appear to be caused by trinucleotide repeats

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Babinski response the plantar response which describes the movement of the toes when the sole of the foot is scratched. Normally the toes flex, but in the case of an upper motorneuron lesion the toes extend.

Ballismus movement disorder characterised by wide, flailing movements of the limbs-normally on one side (hemiballismus)-caused by a lesion in the contralateral subthalamic nucleus

Bell's palsy idiopathic lower motorneuron lesion of the seventh cranial nerve

Benign positional vertigo condition of paroxysmal vestibular dysfunction typically following head trauma or inner ear infections, characterised by intense vertigo, nausea and vomiting with postural changes in head position

Berry aneurysm congenital aneurysms on the circle of Willis

Blindsight clinically describes patients with bilateral damage to V1, in which they deny being able to see any visual stimulus even though on formal testing they are capable of localizing visual targets accurately

Brown-Séquard syndrome a syndrome of spinal cord hemisection with an ipsilateral upper motorneuron lesion below the level of the spinal cord involvement in association with an ipsilateral loss of light touch, vibration perception and joint position sense and a contralateral loss of pain and temperature

Bulbar palsy describes a condition in which there is damage and/or dyfunction of the lower cranial nerves (IX-XII) innervating the pharynx and larynx

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Carpel Tunnel Syndrome (CTS) entrapment of the median nerve at the wrist with weakness of the thumb and loss of sensation in the thumb, index, middle and half of the ring finger. It can present with pain during the night and first thing in the morning.

Cataplexy sudden loss of muscle tone associated with emotional upset or laughter. It is often associated with narcolepsy

Cataracts loss of the normal clear crystalline nature of the lens

Central aqueduct stenosis condition in which there is narrowing of the central aqueduct connecting the third and fourth ventricles in the midbrain which can lead to hydrocephalus

Cerebral palsy non-progressive insult to the CNS that occurs at birth, usually as a result of birth hypoxia or intrauterine infection

Cerebrovascular accident (CVA) term used to describe a significant and permanent arterial vascular insult of the CNS

Chorea abnormal movement disorder which is characterised by jerky dance-like movements of the affected parts

Creutzfeldt-Jakob Disease (CJD) is a rare prion disorder that can occur sporadically, as a consequence of using infected graft material (eg dural graft - latrogenic CJD) and probably through BSE infected meat (causing new variant CJD). In all cases patients present with a rapidly progressive neurological disorder with dementia, ataxia and myoclonus.

Choroid plexus papilloma rare tumour of the choroid plexus in which there is oversecretion of CSF causing hydrocephalus

Clonus involuntary rhythmic movements due to an upper motorneuron lesion and exaggerated reflexes.

Cortical dysplasia a developmental abnormality in which cells destined for the cortex migrate to aberrant sites and may cause epilepsy

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Deafness a loss of hearing

Decerebrate posture extensor posturing associated with severe brainstem damage

Dementia of the Alzheimer's type (DAT) dementia characterised by the early loss of anterograde memory and language with a disease process that is initially localised to the temporoparietal cortices. As the disease progresses other cognitive functions are lost. There is a loss of the neurons in the cholinergic forebrain nuclei which innervate the cerebral cortex, which itself contains neurofibrillary tangles and senile neuritic plaques, as does the hippocampus. Most cases are sporadic but familial forms of the disease exist

Demyelinating neuropathies peripheral nerve damage in which the primary event is a loss of myelin, causing slowing of nerve conduction which can eventually be lost altogether. Guillain-Barré syndrome is an example of such a neuropathy

Depression Depression is characterized by sadness, apathy, low self-esteem and a tendency to withdraw from others coupled to a loss of libido, anorexia and early morning waking.

Dermatomyositis inflammatory condition affecting the skin and proximal muscles, which can be associated with an underlying malignancy (see Paraneoplastic syndrome, Chapter 46)

Diabetes Insipidus (DI) a condition in which there is an inability to concentrate urine because there is either loss of production of antidiuretic hormone (neurogenic DI) or loss of efficacy because of receptors nor responding in the kidney (nephrogenic DI)

Diabetes Mellitus (DM) high blood glucose because there is either a loss of insulin production (type or young onset insulin dependent DM- IDDM) or a loss of efficacy as receptor becomes less responsive (type II or late onset non-insulin dependent DM - NIDDM)

Diplopia double vision

Dysarthria or anarthria inability to articulate words normally, while the comprehension and expression of language is normal. A complete inability to utter any word is termed anarthria

Dysphagia difficulty with swallowing which can be due to neurological disorders as well as mechanical lesions of the palate and oesophagus

Dysphasia or aphasia inability to either understand spoken language (a receptive dysphasia) or express it (an expressive dysphasia) without any impairment in articulation. A complete inability to understand or speak is termed aphasia

Dystonia movement disorder in which there is a fixed abnormal posturing of a part of the body

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Encephalitis Inflammation of the brain, typically viral in nature and especially with the herpes simplex virus

Ependymoma a tumour of the cells lining the ventricles of the brain or central canal of the spinal cord

Epilepsy abnormal discharge of a network of neurons that causes either a focal or generalised disturbance of CNS function

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Friedreich's ataxia trinucleotide repeat, autosomal recessive disorder in which there is a progressive loss of the dorsal columns and spinocerebellar tracts with skeletal and heart abnormalities

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Guillain-Barré syndrome inflammatory demyelinating peripheral neuropathy that can complicate systemic illnesses and diarrhoeal diseases caused by Campylobacter jejuni

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Hemiplegia complete loss of power down one side of the body

Hemiparesis weakness down one side of the body

Homonymous hemianopia a visual field defect defined as a matched loss of vision involving half the visual scene

Horner's syndrome loss of the sympathetic innervation to the eye causing miosis, ptosis, enophthalmos and anhydrosis

Huntington's disease trinucleotide repeat, autosomal dominant condition characterised by progressive dementia and the development of a movement disorder, most commonly chorea

Hydrocephalus is defined as dilatation of the ventricular system and so can be seen in cases of cerebral atrophy, e.g. dementia (compensatory hydrocephalus).

Hyperphagia excessive eating which is seen with damage to parts of the hypothalamus

Hyperreflexia increased tendon reflexes, which typically occurs with an upper motorneuron lesion

Hyperekplexia condition in which there is an excessive startle response and which can be associated with abnormalities of the glycine receptor

Hypertonia increased muscle tone, which typically occurs with an upper motorneuron lesion

Hypotonia reduce muscle tone, which typically occurs with a lower motorneuron lesion

Hyporeflexia reduce tendon reflexes, which typically occurs with a lower motorneuron lesion

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Insomnia the inability to sleep

Internuclear opthalmoplegia (INO) an eye movement disorder that is due to a lesion in the medial longitudinal fasciculus in the brainstem. The lesion is typically a demyelinating plaque in Multiple sclerosis. The clinical features of an INO are nystagmus in the abducting eye and slowed or absent adduction in the other eye

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Jacksonian march an epileptic seizure that originates in the primary motor cortex and which classically starts with abnormal movements in the thumb then spreads to the hand, then arm, then face.

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Keratitis infection of the cornea

Korsakoffs syndrome Damage to the mammillary bodies, which receive a significant input from the hippocampal complex as occurs in chronic alcoholism with thiamine deficiency, produces a profound amnesia (Korsakoff's syndrome) of both an anterograde (inability to lay down new memories) and retrograde (inability to recover old memories) nature. The latter feature distinguishes these patients from those who have hippocampal damage and may explain why patients with Korsakoff's syndrome tend to invent missing information (confabulation).

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Lambert-Eaton myasthenic syndrome autoimmune condition in which there is proximal weakness with autonomic dysfunction associated with antibodies to the presynaptic voltage-gated Ca2+ channel at the neuromuscular junction. In 50% of cases it represents a paraneoplastic syndrome

Lateral medullary syndrome of Wallenberg constellation of signs associated with occlusion of the posterior inferior cerebellar artery. Classically an ipsilateral Horner's syndrome, and ataxia with a contralateral sensory loss

Lower motorneuron lesion lesion affecting the cranial nerve or spinal cord ventral horn motorneuron and/or its axon and characterised by wasting, weakness and areflexia ± fasciculation

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Malignant hyperthermia/hyperpyrexia This is a condition in which there is an abnormality in the ryanodine receptor which is part of the protein complex linking the T-tubule to the SR. This leads, under certain circumstances such as general anaesthesia, to sustained depolarization, contraction and necrosis of muscles resulting in an increase in body temperature and multiorgan dysfunction.

Malignant meningitis describes a condition where a tumour can invade and grow in the meninges causing damage to the nerve roots as they come out, and so presenting with painful cranial and spinal nerve lesions

Mania Mania is characterized by euphoria, delusions of grandeur and mental overactivity

Meninigioma a tumour of the meninges

Meningitis inflammation of the meninges

Migraine common disorder of unknown aetiology in which the patient develops a severe unilateral headache with nausea, vomiting, meningism (neck stiffness caused by meningeal irritation), photophobia (a dislike of lights) and which can be associated with focal neurological phenomena such as flashing lights or a hemiparesis (weakness down one side of the body)

Mitochondrial cytopathies group of disorders characterised by abnormalities of mitochondrial function, either as a result of inherited defects in the mitochondrial DNA or because of abnormalities in nuclear coded mitochondrial proteins

Motorneuron disease degenerative disorder in which there is the selective loss of motorneurons, both upper and lower, which is incurable. There are familial forms of the disorder, some of which are associated with mutations in the copper-zinc superoxide dismutase gene

Multiple sclerosis inflammatory disorder of the CNS of unknown aetiology, that is most often characterised by episodes of inflammation and demyelination disseminated in time and space. In some cases the disease is progressive in which case there may be associated axonal loss

Multiple System atrophy (MSA) neurodegenerative disorder characterised by parkinsonism, autonomic failure and/or cerebellar degeneration. It is incurable and usually fatal within 5-10 years of onset

Muscular dystrophies group of inherited muscle diseases that progress with age and are typically associated with inherited genetic defects that code for structural skeletal muscle proteins

Myasthenia gravis disorder of the neuromuscular junction presenting as fatiguable weakness and associated with antibodies to the nictonic acetylcholine receptor. The extraocular, facial, bulbar and proximal limb muscles are especially susceptible to the disease process

Myalgia muscle pain

Myelitis inflammation of the spinal cord

Myopia short sightedness

Myositis inflammation of muscle

Myotonia inability to relax muscles voluntarily

Myotonic dystrophy an inherited disorder which is characterised by frontal balding, facial and distal limb weakness, myotonia, early cataract formation and can be associated with diabetes mellitus and hypogonadism.

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Narcolepsy disorder characterised by short periods of inappropriate sleep during the day, with sleep paralysis and hypnagogic and hypnapompic hallucinations. It is often associated with cataplexy

Neglect syndrome contralateral neglect to sensory stimuli usually associated with lesions of the posterior parietal cortex

Neurofibromatosis type 1 inherited autosomal dominant disorder condition characterised by skin abnormalities, neurofibromas and schwannomas. It is associated with a defect in a tumour suppressor gene on chromosome 17 (neurofibromin). A type 2 form of the disorder exists (linked to chromosome 22) and is associated with bilateral acoustic neuromas

Neuromyotonia or Isaac's syndrome condition in which there is fasciculation of skeletal muscle as a result of abnormal neuromuscular transmission. It is often associated with an antibody to the presynaptic voltage gated potassium channel

Neuropathy any disease process that causes damage and loss of function of the peripheral nerves

Night blindness loss of night sight, typically seen in retinitis pigmentosa

Nystagmus is defined as a biphasic ocular oscillation containing an abnormal slow and corrective fast phase, the latter defining the direction of the nystagmus

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Obstructive Sleep Apnoea (OSA) a disorder in which there is mechanical obstruction of the upper airway leading to oxygen desaturations at night, which causes disturbed sleep.

Oligodendroglioma a tumour of oligodendrocytes

Oscillopsia perception of an oscillating image or environmental movement

Otosclerosis sclerosis of stapedial foot process in the oval window of the cochlea

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Palatal tremor/myoclonus This is a rare condition in which there is hypertrophy of the inferior olive, with damage in a triangle bounded by this structure, the dentate nucleus of the CBM and the red nucleus in the midbrain (Mollaret triangle). The patient characteristically has a low-frequency tremor of the palate, which oscillates up and down.

Paraesthesia positive sensory phenomena such as 'pins and needles'

Paraneoplastic syndrome syndrome in which there is a remote effect of a cancer on a part of the body, in the context of this book, the nervous system. It is thought to be an immunological process in which the host mounts an immune response to a tumour which then cross-reacts with a normal component of the nervous system. It is most commonly seen in lung and breast carcinomas. Examples include dermatomyositis and Lambert-Eaton myasthenic syndrome

Parkinson's disease idiopathic neurodegenerative condition of the nigrostriatal pathway that primarily affects late middle-aged people, and presents with tremor, rigidity and slowed movements (bradykinesia)

Periodic paralyses rare group of conditions in which there are episodes of paralysis (but sparing the respiratory muscles) associated with abnormalities in ion channels (hence 'channelopathies')

Poliomyelitis infective condition caused by a virus that has a predilection for the anterior horn motorneurons. It is now rare in the UK and USA as a result of national vaccination programmes

Polymyositis inflammatory condition of the proximal skeletal muscles that can affect the bulbar musculature, and which can also be associated with underlying systemic autoimmune illnesses

Post-herpetic neuralgia severe pain that is experienced in the region of a previous shingles rash, which itself represents a reactivation of the herpes zoster virus in the distribution of a dermatome, commonly the first ophthalmic division of the trigeminal nerve

Prader-Willi syndrome a genetic disorder that presents in childhood with hyperphagia, obesity and mental retardation.

Prion disease See CJD

Proprioception ability to know where limbs and joints are in space, also known as joint position sense

Prosopagnosia inability to recognise faces, caused by damage of the non-dominant temporal lobe

Pseudobulbar palsy damage to the descending pathways to the nerves (i.e. cranial nerves IX-XII) innervating the pharynx and larynx

Ptosis drooping of the upper eyelid over the eye. It can be congenital in nature but is also seen in other conditions such as myasthenia gravis and a IIIrd nerve palsy

Primary autonomic failure a condition of unknown aetiology in which there is loss of central components of autonomic nervous system.

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Radiculopathy process that involves the nerve root as it emerges from the spinal canal through the exit foramena in the vertebrae. Such a process is typically degenerative in nature as with disc prolapse and new bone formation (osteophytes)

Reflex sympathetic dystrophy condition in which following minor trauma to a limb, there is the development of a pain syndrome with trophic changes in the affected area (altered vascularity and sweating; thinning of the skin)

Relative afferent pupillary defect a lesion in the optic nerve will produce a smaller direct than consensual pupillary response, so that as the light is shone from unaffected to affected eye the pupil gets paradoxically bigger.

Retinitis pigmentosa condition, often inherited, in which there is degeneration of the rods and cones in the retina

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Sarcoidosis inflammatory condition of unknown aetiology that can affect any part of the body, including the muscle, peripheral nerve, spinal cord, optic nerve, eye and more rarely other supraspinal structures

Schizophrenia is a syndrome characterized by specific psychological manifestations, including auditory hallucinations, delusions, thought disorders and behavioural disturbances

Schwannoma a tumour of schwann cells that can be associated with Neurofibromatosis

Spasticity increased tone as a result of an upper motor neuron lesion

Spina bifida condition in which there is incomplete fusion of the spine. This typically occurs in the lumbar region but can also be seen in the cervical region. In the lumbar spine it can be asymptomatic, but it can also cause a host of deficits as a result of developmental disruption of the structures originating at that site (e.g. bladder dysfunction and limb weakness and numbness). In addition, hydrocephalus may ensue resulting from obstruction of the CSF flow and/or failure to reabsorb CSF through the arachnoid villi

Stiff-person syndrome rare condition in which there is abnormal rigidity in the muscles adjacent to the spine and abdomen, often in association with antibodies to the gamma-aminobutyric acid (GABA) synthetic enzyme-glutamic acid decarboxylase (GAD). It is associated with autoimmune disorders especially insulin dependent diabetes mellitus

Subacute combined degeneration of the cord condition in which the posterior parts of the spinal cord demyelinate and may degenerate as a result of vitamin B12 deficiency

Sydenham's chorea rare sequelae of a streptococcal throat infection, often in the context of rheumatic fever. It is also known as St Vitus's dance and is self-limiting with abnormalities on brain scanning in the basal ganglia in some cases. Typically, patients display chorea and slight disruption of frontal lobe function

Syringomyelia condition in which there is the development of an abnormal cyst-like structure in the middle of the spinal cord. It characteristically presents with dissociated sensory loss as the pain and temperature fibres forming the spinothalamic tract being preferentially affected. If this extends up into the brainstem it is termed syringobulbia

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Tabes dorsalis late complication of syphilis infection in which there is loss of the dorsal spinal roots and dorsal columns. Patients therefore present with pain and profound proprioceptive deficits

Temporal Lobe Epilepsy (TLE) a form of epilepsy that takes its origin in the temporal lobe and presents with a odd tastes, smells, autonomic dysfunction and a range of other symptoms which may include a period of altered consciousness.

Transient Ischaemic attacks (TIAs) transient ischaemic attacks are brief disturbances (<24 hours) in neurological function as a result of a transient disturbance in blood supply to a part of the brain, normally as a result of a narrowing in the carotid arteries

Transverse myelitis inflammation involving the whole of the spinal cord at one (or several) levels

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Upper motorneuron lesion lesion that interrupts the corticospinal (and probably rubrospinal) projection to the anterior horn and brainstem motorneurons causing increased tone and reflexes with weakness that is more in the extensors in the upper limb and flexors in the legs

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Vasculitides group of conditions in which the primary site of inflammation is within the walls of the blood vessel. The size of blood vessel varies with different diseases, as does the distribution of vessels affected. It can affect muscles and peripheral nerves as well as the CNS

Vasculitis inflammation of blood vessels.

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Wilson's disease an inherited condition in which there is a disorder in copper metabolism which results in neurological problems (movement disorder and dementia) with cirrhosis of the liver.

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