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

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

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

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:

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

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

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

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:

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).

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

SSEP electrodes

VEP electrodes

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:

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:

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 follows^7,22:

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.

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

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.

References

1.Federative Committee on Anatomical Terminology. Terminologia Anatomica. Georg Thieme Verlag; 1998.

2.American Clinical Neurophysiology Society. Accessed August 1, 2019. https://www.acns.org

3.International Federation of Clinical Neurophysiology (IFCN). Accessed August 1, 2019. https://www.ifcn.info/

4.Nuwer MR, Comi G, Emerson R, et al. IFCN standards for digital recording of clinical EEG. In: Deuschl G, Eisen A, eds. Recommendations for the Practice of Clinical Neurophysiology: Guidelines of the International Federation of Neurophysiology. Electroencephalogr Clin Neurophysiol. 1998;106(3):259-261.

5.Ropper AH, Samuels MA, Klein JP. Imaging, electrophysiologic, and laboratory techniques for neurologic diagnosis. In: Adams and Victor’s Principles of Neurology. 10th ed. McGraw-Hill; 2014:13-39.

6.Gilmore RL, ed. American Electroencephalographic Society guidelines in electroencephalography, evoked potentials, and polysomnography. J Clin Neurophysiol. 1994;11(1):1-158.

7.Recording techniques. In: Ebersole JS, ed; Sinha SR, Husain AM, Nordli DR, assoc eds. Current Practice of Clinical Electroencephalography. 4th ed. Lippincott Williams & Wilkins; 2014:78-89.

8.Schomer DL, Lopes da Silva F, eds. Niedermeyer’s Electroencephalography: Basic Principles, Clinical Applications, and Related Fields. 6th ed. Lippincott Williams & Wilkins; 2012.

9.Jasper HH. Report of the Committee on Methods of Clinical Examination in Electroencephalography: 1957. Electroencephalogr Clin Neurophysiol. 1958;10(2):370-375.

10.Rowan AJ, Tolunsky E. Primer of EEG: With a Mini-Atlas. Butterworth-Heinemann; 2003.

11.Hughes JR. EEG in Clinical Practice. 2nd ed. Butterworth-Heinemann 1994:2.

12.Sharbrough F, Chatrian G-E, Lesser RP, Lüders H, Nuwer M, Picton TW; Electrode Position Nomenclature Committee. American Electroencephalographic Society guidelines for standard electrode position nomenclature. J Clin Neurophysiol. 1991;8(2):200-202.

13.Chatrian G-E, Lettich E, Nelson PL. Modified nomenclature for the “10%” electrode system. J Clin Neurophysiol. 1988;5(2):183-186.

14.Nuwer MR. Recording electrode site nomenclature. J Clin Neurophysiol. 1987;4(2):121-133.

15.Acharya JN, Hani A, Cheek J, Thirumala P, Tsuchida TN. American Clinical Neurophysiology Society Guideline 2: Guidelines for Standard Electrode Nomenclature. J Clin Neurophysiol. 2016;33(4):308-311.

16.Noachtar S, Binnie C, Ebersole J, Mauguière F, Sakamoto A, Westmoreland B. A glossary of terms most commonly used by clinical electroencephalographers and proposal for the report form for the EEG findings. In: Deutschl G, Eisen A, eds. Recommendations for the Practice of Clinical Neurophysiology: Guidelines of the International Federation of Neurophysiology. Electroencephalogr Clin Neurophysiol Suppl. 1999;suppl 52:21-41.

17.American Association of Electrodiagnostic Medicine. Guidelines in electrodiagnostic medicine, 6: guidelines in somatosensory evoked potentials. Muscle Nerve. 1999;22(suppl 8):S111-S118.

18.Celesia GG, Bodis-Wollner I, Chatrian GE, Harding GFA, Sokol S, Spekreijse H. Recommended standards for electroretinograms and visual evoked potentials: report of an IFCN committee. Electroencephalogr Clin Neurophysiol. 1993;87(6):421-436.

19.Nuwer MR, Aminoff M, Goodin D, et al. IFCN recommended standards for brain-stem auditory evoked potentials: report of an IFCN committee. Electroencephalogr Clin Neurophysiol. 1994;91(1):12-17.

20.Deutschl G, Eisen A, eds. Recommendations for the Practice of Clinical Neurophysiology: Guidelines of the International Federation of Neurophysiology. Electroencephalogr Clin Neurophysiol. 1999;S52:1-304.

21.Radtke RA. Sleep disorders: laboratory evaluation. In: Ebersole JS, ed; Sinha SR, Husain AM, Nordli DR, assoc eds. Current Practice of Clinical Electroencephalography. 4th ed. Lippincott Williams & Wilkins; 2014:599-630.

22.American Academy of Sleep Medicine. The International Classification of Sleep Disorders, Revised: Diagnostic and Coding Manual. American Academy of Sleep Medicine; 2001.

23.Nestler EJ, Hyman SE, Holtzman DM, Malenka RC. Molecular Neuropharmacology: A Foundation for Clinical Neuroscience. 3rd ed. McGraw-Hill; 2015.