Neurological Glossary
Lacunar stroke/ lacunar infarct
A small stroke affecting an area of tissue less than one centimetre in diameter
Lateral
Further from the midline
Lambert-Eaton Myasthenic syndrome
Autoimmune disorder of neuromuscular transmission characterised by antibodies directed against the voltage-gated calcium channels on the presynaptic motor nerve terminal leading to impaired release of acetylcholine and causing proximal muscle weakness, hyporeflexia, and autonomic changes (e.g., dry mouth); associated with malignancy (particularly small cell lung cancer)
Laminar necrosis
Selective neuronal loss in layers 3 and 5 of the cerebral cortex due to hypoxic-ischemic insult
Lateral medullary syndrome (Wallenberg's syndrome)
Constellation of symptoms including difficulty swallowing, hoarseness, vertigo, nystagmus, ataxia, loss of pain and temperature sense in the ipsilateral face and contralateral body, and ipsilateral Horner's syndrome in association with an infarct in the lateral medulla; due to occlusion of the vertebral or posterior inferior cerebellar artery
LD
Learning Difficulties
LDL (Low Density Lipoprotein)
The source of waxy plaque on the artery walls. LDL is usually called bad cholesterol
Left hemisphere
The brain has two sides to it, known as the left hemisphere and right hemisphere, each controlling different functions. Amongst other things, the left side controls speech and writing.
Lennox-Gastaut syndrome
Syndrome of mental retardation, generalized epilepsy (with mixed seizures, especially tonic, myoclonic and atypical absence), and a characteristic pattern of slow, generalized spike-and-wave activity on the electroencephalogram
Lentiform nucleus (lenticular nucleus)
Lens-shaped part of the basal ganglia consisting of the putamen and globus pallidus
Leptomeninges
Arachnoid mater and pia mater
Lethargy
A state of sluggishness, drowsy dullness or apathy.
Leukodystrophy
Metabolic demyelinative disease
Lewy body
Cytoplasmic, bright red sphere often with a surrounding halo on H&E composed of an amorphous granular core with a radiating filamentous periphery; believed to contain alpha-synucein; seen in Parkinson disease and diffuse Lewy body disease
Lewy body dementia
Type of dementia that is caused by small proteins that form on the nerve cells in the brain disrupting memory and motor control. It can also cause changes in attention, such as tiredness and loss of speech, and motor symptoms such as rigidity and loss of spontaneous movement
Light-near dissociation
Absent pupillary light response but intact near response (i.e., “accommodate but don’t react”) seen with dorsal midbrain lesions, syphilis, and diabetes
Limbic
Referring to the system comprising the hippocampus, parahippocampal gyrus, cingulate gyrus, fornix, and multiple subcortical structures including portions of hypothalamus and thalamus; important in memory and emotion
Lipohyalinosis
Eosinophilic deposits in the connective tissue of the walls of perforating arterioles in the deep portions of the brain due to hypertension; contributes to the development of lacunar infarction and hypertensive hemorrhage
Lipoproteins
Cholesterol travels though the blood through different compounds called lipoproteins, a combination of fat and protein
Lissauer’s tract
Longitudinal bundle of thin, unmyelinated and poorly myelinated fibres capping the apex of the posterior horn of the spinal gray matter, composed of posterior nerve root fibers and short association fibers that interconnect neighboring segments of the posterior horn
Lissencephaly (agyria)
Smooth brain (absence of secondary sulci)
Lobe
One of four major portions of the cerebral cortex named after the overlying cranial bones: frontal, parietal, temporal, and occipital
Locked-in state
Tetraplegia and aphonia with preserved consciousness due to brainstem (usually pontine) lesion that spares the reticular activating system
Locus ceruleus
Melatonin-containing nucleus located on the dorsal wall of the upper Pons that is one of the main sources of neuroepinepherine in the brain and has widespread projections to other parts of the nervous system; mediates arousal and primes neurons throughout the nervous system to be activated by stimuli
Loftstrand Crutch
Type of crutch with an attached holder for the forearm that provides extra support
Long-tract signs
Signs referable to the corticospinal tract, spinothalamic tract, and dorsal columns/medial lemniscus
Lordosis
Exaggerated hollow in the lower back
Lower motor neuron
Second order neurons whose cell bodies are located in the brainstem or anterior horn of the spinal cord and that leave the CNS to connect to muscle; lesions result in flaccid weakness, reflex loss, atrophy, and fasciculations
Lumbar Puncture
A procedure whereby some of the spinal fluid is removed by the insertion of a needle into the spine, for diagnostic testing
Lycra splint
A material suit that supports the body while allowing function
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