Neurology - Nomenclature

AMA Manual of Style - Stacy L. Christiansen, Cheryl Iverson 2020

Neurology
Nomenclature

14.11.1 Nerves.

Most nerves have names (eg, ulnar nerve or nervus ulnaris). English names are preferred to Latin. For terminology, consult a medical dictionary, anatomy text, or Terminologia Anatomica.1

14.11.1.1 Cranial Nerves.

The cranial nerves are listed in Table 14.11-1.

Table 14.11-1. Cranial Nerves

Nerve

English name

Latin name

I

olfactory

olfactorius

II

optic

opticus

III

oculomotor

oculomotorius

IV

trochlear

trochlearis

V

trigeminal

trigeminus

VI

abducens

abducens

VII

facial

facialis

VIII

vestibulocochlear

vestibulocochlearis (acoustic)

IX

glossopharyngeal

glossopharyngeus

X

vagus

vagus

XI

accessory

accessorius

XII

hypoglossal

hypoglossus

Use roman numerals or English names when designating cranial nerves:

Cranial nerves III, IV, and VI are responsible for ocular movement.

The oculomotor, trochlear, and abducens nerves are responsible for ocular movement.

Use ordinals when the numeric adjectival form is used:

The third, fourth, and sixth cranial nerves are responsible for ocular movement.

14.11.1.2 Vertebrae, Spinal Nerves, Spinal Levels, Dermatomes, and Somites.

These entities share a common nomenclature, deriving from spinal anatomic regions: cervical (neck), thoracic (trunk), lumbar (lower back), sacral (pelvis), and coccygeal (coccyx or tailbone).

Spinal nerves C1 through C7 are named for the vertebrae above which they emerge, while T1 through S5 are named for the vertebrae below which they emerge. Spinal nerve C8 emerges below vertebra C7; there is no C8 vertebra.

Vertebrae and spinal nerves are listed in Table 14.11-2.

Table 14.11-2. Vertebrae and Spinal Nerves

Region

Vertebrae

Spinal nerves

cervical

C1 through C7

C1 through C8

thoracic

T1 through T12

T1 through T12

lumbar

L1 through L5

L1 through L5

sacrum

S1 through S5

S1 through S5

coccyx

4 fused, not individually designated

coccygeal nerve

The alphanumeric terms need not be expanded and, when clear in context, vertebra and nerve need not be repeated:

The first cervical vertebra is also known as the atlas, C2 as the axis, and C7 as the vertebra prominens.

Portions of a vertebra may be referred to as follows, ie, without the term vertebra:

C5 spinous process

L3 lamina

T12 transverse process

Hyphens are used for intervertebral spaces (including neural foramina) and intervertebral disks (Table 14.11-3).

Table 14.11-3. Intervertebral spaces and Disks

Space

Disk

C2-3 (space between C2 and C3)

C2-3 disk

T2-3 (space between T2 and T3)

T2-3 disk

L2-3 (space between L2 and L3)

L2-3 disk

C7-T1 (space between C7 and T1)

C7-T1 disk

L5-S1 (space between L5 and S1)

L5-S1 disk

Note: L4-5 diskectomy is correct usage. Terminologia Anatomica uses disc, not disk. See 11.0, Correct and Preferred Usage.

The sacrum, because its vertebrae are fused, does not contain intervertebral spaces. Its 4 paired foramina are commonly referred to as the first sacral foramen (or S1 foramen), second sacral foramen (or S2 foramen), etc.

Ranges of vertebrae are expressed as in the following examples; use letters for both the first and last vertebra in the indicated range:

C3 through C7

third through seventh cervical vertebrae (not C3 through 7)

T6 through S1

sixth thoracic through first sacral vertebrae

Ranges of vertebrae when used as modifiers have one or more hyphens, eg,

C1-C3 arthrodesis

C2-T1 spinous processes

C4-T3 fusion

L1-L2-L3 motion segments

L1-L4 bone mass density

L2-S1 canal stenosis

L3-L4-L5 fusion

L4-L5 laminectomy

erosion of T9-T12 vertebrae

The same abbreviations are used for spinal segments or levels, spinal dermatomes, and somites (mesodermal structures on either side of the developing spinal cord). Text should indicate which is being referred to, eg, vertebra, spinal nerve (or root, radiculopathy, or distribution), spinal level, dermatome, or somite. Within a clear context, as noted above, the words vertebra, nerve, etc, need not be repeated.

Serious injury of the cervical cord at the level of the C2-C5 vertebrae causes respiratory paralysis due to injury of spinal nerves C3 through C5.

The first patient had herpes zoster in the T9 dermatomal distribution, the second patient in the C5 distribution.

L1-S2 radiculopathy

L3-L4-L5 periradicular infiltration

14.11.2 Electroencephalographic Terms.

Guidelines for electroencephalography (EEG) are available through the American Clinical Neurophysiology Society (formerly the American Electroencephalographic Society)2 and the International Federation of Clinical Neurophysiology3 (formerly the International Federation of Societies for Electroencephalography and Clinical Neurophysiology).4 Other helpful resources include Adams and Victor’s Principles of Neurology,5 the American Electroencephalographic Society guidelines in electroencephalography, evoked potentials, and polysomnography,6 Current Practice of Clinical Electroencephalography,7 and Niedermeyer’s Electroencephalography: Basic Principles, Clinical Applications, and Related Fields.8

The International 10-20 System specifies placement of electrodes used in electroencephalography. The 10-20 system, which originated in the 1950s,9,10 is so named because electrodes are spaced 10% or 20% apart along the head (Figure 14.11-1).

Figure 14.11-1. Electroencephalographic Lead Positions

Image

Reproduced from Hughes11 by permission of Elsevier. Copyright Elsevier 1994.

The terms used in the 10-20 system are widely used and recognized. They are systematically derived, as follows:

■Letters refer to anatomical areas (primarily of the skull, which do not necessarily coincide with the brain areas from which the electrodes register electrical activity).

■Odd numbers are for electrodes placed on the left side, even numbers are for electrodes placed on the right side, and the letter z (“zero”) is for midline electrodes.

Table 14.11-4 lists the electrode designations and locations.

Table 14.11-4. Electrode Designations and Locations

Electrode designation

Location

A1, A2

earlobe

Cz, C3, C4

central

F7, F8

lateral frontal (anterior temporal)

Fp1, Fp2

frontopolar or prefrontal

Fz, F3, F4

superior frontal

O1, O2

occipital

Pz, P3, P4

parietal

T3, T4

midtemporal

T5, T6

posterior temporal

Additional electrodes and other placement systems may be used, for instance, the “modified combinatorial nomenclature,” also known as the 10-10 electrode system, which adds electrodes at intermediate 10% positions.4,12,13,14,15,16 The same electrode may have a different name in the 10-20 and the 10% systems (eg, T3 and T4 in the 10-20 system are referred to as T 7 and T8 in the 10% system).7 The added electrodes result in additional numeric designations for existing regional electrodes (eg, C5, F10) and in new letters or letter-number combinations, as indicated in Table 14.11-5.

Table 14.11-5. Added Electrode Designations and Locations

Added electrode designation

Location

AFz, AF3, AF4, AF7, AF8

anterior frontal

C1, C2, C5, C6

centrotemporal

CPz, CP1, CP2, CP3, CP4, CP5, CP6

centroparietal

FCz, FC1, FC2, FC3, FC4, FC5, FC6, FC7, FC8, FC9, FC10

frontocentral

Fpz

midprefrontal

FT7, FT8, FT9, FT10

frontotemporal

Iz

inion

Nz

nasion

Oz

midoccipital

P1, P2, P5, P6

parietal

P7, P8, P9, P10

posterior temporal

POz, PO3, PO4, PO7, PO8

parieto-occipital or temporal-occipital

Sp1, Sp2

sphenoidal

T1, T2

true anterior temporal

T7, T8, T9, T10

midtemporal

TP7, TP8, TP9, TP10

temporal-posterior temporal

Neonatal electrodes may be placed differently (eg, the 12.5% to 25% system of the Children’s Hospital of British Columbia) and may (or may not) have different designations,7 as in the examples below:

LaF

left anterior frontal

LaT

left anterior temporal

LFC

left frontocentral

LO

left occipital

LP

left parietal

LST

left superior temporal

RaF

right anterior frontal

RaT

right anterior temporal

RFC

right frontocentral

RO

right occipital

RP

right parietal

RST

right superior temporal

In figures showing EEGs, electrode symbols usually will be paired. Usually, the symbols will be beside and to the left of each channel of the tracing but may be above and below each channel with connecting lines. Authors should include with tracings a time marker and an indicator of voltage, as in the top tracing (Figure 14.11-2).

Image

Figure 14.11-2. Sample Electroencephalographic Tracings

Descriptions of EEG potentials include many qualitative terms for waveforms and frequencies. The following are a few of numerous descriptive terms (note that Greek letters are spelled out):

alpha rhythm, beta activity, polymorphic delta activity, sleep spindles, spike-wave complexes, paroxysms, spikes, sharp waves, delta brush, frontal sharp transient, mu rhythm, lambda waves

A comprehensive glossary of EEG terms has been provided by the IFCN.16

Frequency is given per second (/s). For cycles (c) per second, hertz (Hz) is preferred to c/s (see 17.1, SI Units):

10-Hz alpha activity

a theta frequency of 5 to 7.5 Hz

15-Hz spindles

60-Hz artifact

background rhythm of 8 to 10 Hz

14.11.3 Evoked Potentials or Responses.

Several types of evoked potentials or responses (stimulated electrical signals)5(pp13-39),6,17,18,19,20 may be recorded: brainstem auditory evoked potentials (BAEPs or BAERs), somatosensory evoked potentials (SSEPs, including various types such as the following, which are not mutually exclusive: short-latency, upper extremity, lower extremity, median nerve, posterior tibial nerve), and visual evoked potentials or responses (VEPs or VERs, including pattern shift [PSVEP] and flash [FVEP]). As in EEG, evoked potential testing uses recording electrodes and produces tracings.

Electrode terminology resembles that of EEGs (see above), with additional or modified electrodes such as the following,6 which may be used without expansion:

BAEP electrodes

Ac

contralateral earlobe

Ai

ipsilateral earlobe

EAM

external auditory meatus

EAMc

contralateral EAM

EAMi

ipsilateral EAM

M1, M2

mastoid processes

Mc

contralateral M

Mi

ipsilateral M

SSEP electrodes

AC

anterior cervical

C1′, C2′, C3′, C4′

near EEG C1, C2, C3, C4

C2S, C5S

C2, C5 spinous processes

Cc

contralateral C3′ or C4′

Ci

ipsilateral C3′ or C4′

CP

midway between C3 or C4 and P3 or P4

CPc

contralateral CP

CPi

ipsilateral CP

Cz′

near 10-20 Cz

EP

Erb point

EP1, EP2

left and right EP

EPi

ipsilateral EP

Fpz′

near EEG Fpz

IC

iliac crest

L2S, L3S

L2, L3 spinous processes

LN

lateral neck

LNi

ipsilateral LN

PFd, PFp

popliteal fossa (distal, proximal)

REF

reference

T6S, T10S, T12S

T6, T10, T12 spinous processes

VEP electrodes

I

inion

LO

left occipital

LT

left posterior temporal

MF

midfrontal

MO

midoccipital

MP

midparietal

RO

right occipital

RT

right posterior temporal

V

vertex

Waveforms recorded in evoked potential testing are identified with P for positive or N for negative plus a number indicating milliseconds between stimulus and response in neurologically normal adults:

VEP:

N75, N100, N155, P75, P100, P135

SSEP:

N9, N11, N13, N15, N18, N20, N34, N35, P9, P11, P13, P15, P27, P37

SSEPs were recorded from the brachial plexus (Erb point), cervical spine at C2 (N13), and the contralateral parietal area (N19) with a frontal (Fz) reference.

SSEPs showed normal Erb point and cervical potentials and significant delay of scalp components (N20 latency >>3 SDs, N13-N20 central conduction time >3 SDs, bilaterally).

Persistent delay of the P100 wave of the pattern-reversal VEP after an episode of optic neuritis is considered to be compatible with residual demyelination within the optic nerve.

An additional SSEP wave is the LP (lumbar potential).

Other waves, eg, in BAEP, are designated with roman numerals:

I through VII

vertex-positive waves

I′ through VI′

vertex-negative waves

BAEPs of the proband showed normal wave I, increased latency of waves II and III (>3 SDs), and absent IV and V components despite normal hearing acuity.

I-III interpeak interval

V/I amplitude ratio

14.11.4 Polysomnography and Sleep Stages.

Polysomnography is the monitoring of various physiologic parameters simultaneously during sleep,6,21 including the following:

■EEG: standard electrodes are used (see 14.11.2, Electroencephalographic Terms)

■Electro-oculogram (EOG): tracings are obtained from the left eye and right eye

■Electromyogram (EMG): submental (chin) EMG, leg muscle EMG, eg, left anterior tibialis, right anterior tibialis

■Respiratory function, eg, oxygen saturation (Sao2), expired CO2, and tidal volume (VT) (see 14.16, Pulmonary and Respiratory Terminology)

■Electrocardiogram (ECG): see 14.3.1, Electrocardiographic Terms

Sleep stages are as follows7,22:

rapid-eye-movement sleep (REM sleep)

non—rapid-eye-movement (non-REM) sleep (NREM sleep)

sleep stage 1 (N1 sleep)

sleep stage 2 (N2 sleep)

sleep stage 3 (N3 sleep)

sleep stage 4 (N4 sleep)

14.11.5 Molecular Neuroscience.

The following terms are provided for reference (a major source is Nestler et al23) (see 14.10, Molecular Medicine). Terms should be expanded at first mention unless noted otherwise in the Expansion or Explanation column.

Term

Expansion or explanation

α-adrenergic receptor, α receptor (subtypes: α1A, α1B, α1D, α2A, α2B, α2C)

does not require expansion

α-synuclein

does not require expansion

A1, A2

neuropeptide adenosine receptors (also known as purine receptors P1, P2; see 14.6.1, Nucleic Acids and Amino Acids); does not require expansion

ACh

acetylcholine

AChE

acetylcholinesterase

AMPA

α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid

β-adrenergic receptor, β receptor (subtypes: β1, β2, β3)

does not require expansion

BDNF

brain-derived neurotrophic factor

CCR3, CCR5, CXCR4

chemokine receptors (see 14.8.1, Chemokines)

Ch1 through Ch8

cholinergic nuclei

CNTF

ciliary neurotrophic factor

COMT

catechol-O-methyltransferase

cytokines

(see 14.8.4, Nomenclature, Immunology, Cytokines)

δ-receptor

opioid δ receptor

D1 through D5

dopamine receptors

DAT

dopamine transporters

EAAT1, EAAT2, EAAT3, EAAT4, EAAT5

excitatory amino acid reuptake transporters

EGF

epidermal growth factor

GABA

γ-aminobutyric acid

GABAA, GABAB

GABA receptor classes

GABAergic

GABA-mediated

GABA-T

GABA transaminase

GAT-1, GAT-2, GAT-3, GAT-4

GABA family transporters

GDNF

glial cell line—derived neurotrophic factor

GFR

GDNF-neurturin receptor

GIRKs

G protein—coupled Kir3 channels

H1, H2, H3

histamine receptors

5-HT

5-hydroxytryptamine, serotonin (preferred expansion)

5-HT1A, 5-HT1B, 5-HT2A, 5-HT5B, 5-HT7

5-HT receptors

5-HTT

serotonin transporter

5HTTLPR

a polymorphism of the serotonin transporter gene (LPR: length polymorphism region) (see 14.6.2, Human Gene Nomenclature)

interleukins

(see 14.8.4, Cytokines)

IP3

inositol triphosphate

κ-receptor

opioid κ receptor

K(ATP) channel

potassium channel

K(Ca)

Ca2+-gated K+ channel

Kir1, Kir2, Kir3, Kir4, Kir5

inwardly rectifying K+ channels; does not require expansion

L channels, L-type channels

large-current or long-open-time Ca2+ channels; does not require expansion

μ-receptor

opioid μ receptor

M1 through M5

muscarinic receptors; does not require expansion

MAO

monoamine oxidase

MAOA, MAOB

major forms of MAO

N channels

neuronal Ca2+ channels; does not require expansion

nAChRs

nicotinic acetylcholine receptors

NET

norepinephrine GABA family transporter

neuromedin B

does not require expansion

neuromedin K

does not require expansion

neuropeptide Y

does not require expansion

NGF

nerve growth factor

NK1, NK2, NK3

neuromedin K tachykinin receptors

NMDA

N-methyl-D-aspartate

nNOS

neuronal nitric oxide synthetase

NSF

N-ethylmaleamide sensitive factor

NT-3, NT-4

neurotrophin 3 and neurotrophin 4

NTS1, NTS2

neurotensin receptors

P channels

Purkinje Ca2+ channels; does not require expansion

P1, P2

neuropeptide purine receptors (also known as adenosine receptors A1, A2; see 14.6.1, Nucleic Acids and Amino Acids); does not require expansion

R-PTK

receptor-associated protein tyrosine kinase

σ-receptor

opioid σ receptor

SERT

serotonin GABA family transporter

SNAP-25

synaptosomal-associated protein of 25 kDa

SNAP

soluble NSF attachment protein (note different expansion of SNAP than for SNAP-25)

SNARE proteins

SNAP receptors

SNAREpins

hairpin forms of SNARE proteins

substance P

does not require expansion

T channels

transient Ca2+ channels; does not require expansion

t-SNARES

t: target membranes

VAChT

vesicular transporters of ACh

VAMP

vesicle-associated membrane protein, synaptobrevin

VGAT

vesicular transporter for GABA

VGLuT1

vesicular transporter for glutamate

VMAT1

vesicular transporter for monoamines

v-SNARE

v: vesicle

Y1, Y2, Y4, Y5, Y6

neuropeptide Y receptors

Gene symbols for many of the above terms are found in the list of genes in 14.6.2, Human Gene Nomenclature. For reference, gene symbols are given in Table 14.11-6 for terms in the preceding list whose abbreviations do not closely resemble the gene symbol.

Table 14.11-6. Gene Symbols in Genes Whose Abbreviations Do Not Closely Resemble the Gene Symbol

Term

Gene symbol

A1

ADORA1

AMPA

GRIA1

δ receptor

OPRD1

D1

DRD1

H1

HRH1

5-HT1A

HTR1A

κ receptor

OPRK1

μ receptor

OPRM1

M1

CHRM1

nAChR

CHRNA1

neuromedin K

TAC3

NMDA

GRIN1

σ receptor

OPRS1

substance P

TAC1

transporters (various)

SLC genes (various, eg, SLC6A1)

Y1

NPY1R

Principal Author: Cheryl Iverson, MA

Acknowledgment

Thanks to Roger N. Rosenberg, MD, formerly with JAMA Neurology, and Department of Neurology, University of Texas Southwestern, Dallas; Jeffrey L. Saver, MD, JAMA, and Geffen School of Medicine at UCLA, Los Angeles, California; and Christopher C. Muth, MD, JAMA. Thanks also to David Song, JAMA Network, for obtaining permissions.

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