1. 1
Dr. Mohammed Alruby
Diagnostic Aids
Part 3
{Radiographs and Photographs}
{BMR and EMG}
Prepared by
Dr. Mohammed Alruby
Radiographs

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Dr. Mohammed Alruby
Means: A procedure that uses a type of high-energy radiation called x-rays to take pictures of
areas inside the body. X-rays pass through the body onto film or a computer, where the pictures
are made
Types:
Intra-oral radiographs:
Periapical radiographs:
It is necessary for any orthodontic diagnosis for the following reasons:
The pattern and amount of root resorption of deciduous teeth
Presence or absence of permanent teeth, their size, shape, position and relative state of
development
Congenital absence of teeth or presence of supernumerary teeth
Character of alveolar bone, lamina dura, and periodontal membrane
Morphology and inclination of permanent teeth roots
Pathological oral condition such as thickened periodontal membrane, periapical infection, root
fractures, cysts, retained deciduous teeth
Abnormal path of eruption of permanent teeth
Malposition of individual as: rotation, which requires a larger space on the arch
Very useful in mixed dentition analysis
Recognition of exact position of impacted tooth by using method of parallax: that determine
whether the unerupted tooth is located labially or palatally. Two periapical radiograph is taken
with the film in the same position in each exposure, but the tube is moved in second exposure about
10cm. if the impacted tooth is moved in the same direction as the tube so the tooth is impacted
palatally and the reverse is versa.
Bit-wing radiographs:
Is used mainly for detection of proximal cries, but it is of little value in orthodontic diagnosis
Occlusal film:
Occlusal projection is useful to locate the supernumerary teeth at the midline (mesiodens) and to
determine accurately the position of impacted maxillary cuspids
Extra-oral radiographs:
Cephalometric radiographs:
Lateral cephalometric radiographs
PA cephalometric radiographs
Lateral oblique cephalogram:
The patient is directed by 45 degree and take the shot
Since dentofacial structure will be superimposed in the true lateral cephalometric projection, the
lateral oblique direction is designed to gives a more accurate recording of the actual tooth position
in either the left or right buccal segments depending on which side is approximately perpendicular
to the central rays
The lateral oblique cephalogram combines most of advantages of the lateral views, intra-oral
periapical survey and panoramic radiograph plus a standard cephalometric registration that
makes possible measurements of bone size and eruptive movements so it is of particular size in
analysis of developing dentition
Submental vertex cephalometric:

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Dr. Mohammed Alruby
Is used to assess mandibular asymmetry in the transverse and anterior-posterior plane. It is an
important aid in detecting asymmetry in the symphysis, body, ramus, and condyle of the mandible.
In many cases of asymmetry, this view is important for evaluation of mandibular displacement or
rotation of the entire mandible
Panoramic radiograph:
Types:
Panorex:
Developed by Hudson et al 1957, the film and x-ray tube rotate around the mobile head, switching
in the mid-course between the left and right sides.
The result in double exposures of the structure located at the midline, so that, the film is cut at the
midline and the central blurred area is removed and the two halves are taped together
Rotograph:
Developed by Paatero and modified by Blackman 1960
The patient and the apparatus are rotated in opposite directions
The resulting film is a continuous image from condyle to condyle
Orthopantomograph:
Developed by Paatero 1961, 3 axis of rotations are used, the x-ray tube and the cassette rotates
around the head. The film is mobile while the patient is mobile
Panograh:
Developed by Walter and modified by Blackman 1960—1961,
This method is not based on laminograph as most panorama but brings the x-ray source into the
mouth. A flexible cassette is surround the mandible and other surround the maxilla, so that, two
separate panoramic view are obtained for both maxilla and mandible because of the short x-ray
tube – film distance, the magnification is about double to the natural size of the teeth
Sectograph:
Developed by Ricketts 1962, the patient is seated according to the cephalometric requirements, the
x-ray tube and the film travels in recti linear motion instead of curve
This result in panoramic unilateral view of each side of the face, in addition, frontal view can be
obtained at any desired level
Importance of panoramic radiograph:
Panoramic view records the teeth and their supporting structures from condyle to condyle without
superimposition, so it important to:
Visualize in one film, the relationship of both dentition, both jaws and both TMJ
Study the relative developmental status of the teeth, it is important in mixed dentition analysis, it
gives an idea about:
Sequence of calcification: compared to the normal standard as Nolla stages of calcification
Prediction of eruption from sequence of calcification
To know the sequence of eruption of the teeth
To study the pattern of primary teeth root resorption
To detect abnormal path of eruption
To ascertain any pathological lesion
To detect any abnormalities in the teeth number (congenital absence and supernumerary teeth),
tooth size and morphology
The panoramic radiograph shows a differential enlargement so it cannot use cephalometric
measurements

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Dr. Mohammed Alruby
Hand wrist radiograph:
Radiographs of TMJ:
Clinical Photographs
Facial photographs are of great importance when the extra oral radiographs are not available,
are of great importance as pre-treatment and post-treatment permanent records by which the facial
changes achieved by treatment and / or growth can be easily detected
Importance of facial photographs:
To determine facial type of the patient: dolichocephalic, brachycephalic, Mesocephalic
To determine the facial profile: convex, concave, straight profile
To study the soft tissue relationship especially the lips during the rest and during smiling
To study the facial harmony and balance and to detect any facial a symmetry
Used as pre-treatment and post-treatment records for detection of changes due to growth and / or
treatment and for discussion the case with the parents
Teaching needs: slides are probably the most important teaching aids in orthodontics if cases are
to be used in lecturer, posts, and papers and presentation
In all position, the head of the patient should be oriented according to the cephalometric
orientation so that:
= the FH plane should be parallel to the floor
= it is best to take the photographs when the patient in the cephalostate. The camera is attached
to the x-ray cone
= to avoid distortion, it is usually necessary to utilize a telephoto lens, two 100 watt light source
should be placed on each side of the face, or by using an electronic ring flash
1st
position:
= the patient is sitting in an upright position with the teeth in centric occlusion and lips in repose
position
= take frontal and profile views
2nd
position:
= The patient is sitting in an upright posture with the mandible in physiologic rest position
= Take frontal and profile views
3rd
position:
= The patient is sitting in an upright posture while smiling
= Take frontal and profile views
= This position is helpful in detection of short upper lip and gummy smile
Physioprint photographs: Sassoni photographs:
= reproduce the contour of the face at different levels of depth
= it provides a contour map of the face, as well as an accurate facial dimensions
= when the contour and dimension of the face are considered, no two faces are similar
= physioprint can be used to produce synthetically the 3 dimensional architecture of the face
The set up:
A slide representing a millimeter grid is projected onto the face using a standard slide projector
(2x2 or 3x4 inches) which placed 100 inches away from the patient
The millimeter grid has two heavy lines one vertical representing the midline of the face and the
other is horizontal and represent the FH of the patient so, the grid should be adjusted on the face,

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Dr. Mohammed Alruby
so that, the vertical line is coinciding with the patient face midline and pass through nasion, and
the horizontal line should coincide with FH and pass through the orbital and tragus of the ear
The subject is seated in upright position (in cephalostate) facing to the projector and photograph
is taken at a right angle to the side of the face
The camera and film:
The accuracy of this method depends on the following condition:
The camera and projector should be oriented at right angle to each other
The camera, projector and FH should be at the same horizontal level
Distortion and magnification can be completely avoided if the camera is 60 inches from the
subjects and the projector is 100 inches from the subjects
This method has two major applications:
Serial growth study of the facial soft tissue structure by taken a serial physioprint of the same
patient at a regular interval (physioprint is a standardized photo)
Comparison of changes occurred by growth and /or treatment with original pre-treatment
physioprint
Furthermore, it can be used for anthropometric studies of racial variation in the face
3 dimensional form of physioprint can be used in study of facial balance in 3 dimension of the face
Standardized orthodontic views:
For complete photographic record, the recommended views are:
Initial:
Four extra-oral: left profile (right profile in only cases with facial asymmetry), Three quarter
profile, full face,
Five intra-oral: occlusion right and left buccal segment, anterior view, upper and lower occlusal
surface
Close up of any areas of concern, fractured cracked, or non-vital teeth or area of hypoplasia
Progress:
during the treatment or between phases of treatment: same as the initial stage of treatment
close up: of any of unusual or noteworthy mechanics or problem area, removable appliances used
during treatment are often photographed in case to be presented.
End of treatment:
Same as initial: photographs of the retainer can be useful, and also for functional occlusion
Right and left lateral excursion and anterior protrusion will be demonstrated
Clinical procedure:
Photographs should definitely proceed impressions, since alginate invariably remains on lips and
cheeks and between the teeth. take extra-oral before intra-oral photographs because the patient
lips will be pulled and stretched during the intra-oral photograph
Extra-oral photographs
Full-face extra-oral view:
= A symmetrical shot from the top of the patient’s head to an inch or two below the chin
= Take one full face view with the lips at rest and one with as broad smile as possible, fully exposing
the teeth and gingivae
Frontal at rest: Mandible in rest position ad lips should be in repose position.
Frontal with teeth in intercuspation: Lips is closed even with strain position for the patient, this
photo serves as clear documentation of lip strain and its esthetic effect

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Dr. Mohammed Alruby
The lip together picture is recommended in patient who have lip incompetence
Frontal with smile: The smile picture demonstrate the amount of incisors show on smile and an
excessive gingival display
Close up image with posed smile: This view is now recommended as a standard photograph for
careful analysis of smile relationships
Profile extra-oral view:
A photograph from the top of patient’s head to an inch or two below the chin
The patient’s nose should be a short distance from the edges of the frame, the back of the head is
not essential
Profile at rest: The lips should be relaxed. Lip strain is illustrated better in frontal
Profile with smile: Allows one to see the angulation of the maxillary incisors
Three quarter extra-oral view:
A shot from the top of the head to one or two inches below the chin
The patient’s body should be at a right angle to the camera as in the profile
Focus on the cheekbone and the side of the nose to ensure adequate depth of filed
The patient in natural head position looking 45 degree to the camera
Oblique at rest: useful for examination of the midface and is particularly informative of midface
deformities including nasal deformity. For patient with facial asymmetry, oblique views for both
sides are recommended
Oblique on smile: reveals characteristic of smile that cannot obtained from the frontal view and
certainly not obtained from cephalometric analysis
Oblique close up smile: allows more precise evaluation of the lip relationships to the teeth and
jaws than is possible using the full oblique view
Optional submental view:
This view may be taken to document mandibular asymmetry, in patients with asymmetries the
submental views can be particularly revealing
Silhouette photograph:
In photography, a silhouette is defined as an outline that appears dark against a light
background. More specifically, it is where your subject is seen as a black shape without detail
against a brighter background. This is an artistic outcome that many photographers like to
perfect. This effect can be achieved with any kind of bright light source, but of course the most
commonly used is the sun around sunrise or sunset. The backlighting from the sun shadows
everything towards you and produces this effect.
Intra-oral photographs:
5 different views are necessary, 3 of which (frontal, right and left view) should be taken with teeth
in occlusion. Other 2 views for maxillary and mandibular arch
Check retractor is used to allows proper exposure of teeth, gingiva and alveolar mucosa
Importance of intra-oral photographs:
1- The most valuable intra-oral photographs are buccal and frontal views with the teeth in
occlusion since they enable the dentist to check the occlusion and to classify the
malocclusion more accurately
2- Useful in discussion with parents

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Dr. Mohammed Alruby
3- Used as permanent records to which the changes due to treatment and / or growth can be
compared
4- It is very useful in detection of some condition which cannot be seen on the dental cast as,
gingival condition, enamel hypoplasia, and discoloration, mottled enamel, amylogenesis
imperfecta,
Intra-oral anterior view:
Objectives: to show the teeth in intercuspation with viewfinder completely filled with teeth, the
buccal surface of molar may be visible
Subject: the patient seated on dental chair and the assistant retracting the lips and cheeks, ask the
patient to keep the tongue back to allows good contrast for the teeth
Procedure: because anterior shots require maximum retraction, larger retractors must be used on
all patients
Ask the patient to swallow before placing the retractors and aspirate excess saliva from the field
of view. For adequate depth of field, focus on the lateral incisors area or the mesial of the canine
by rocking gently backward and forward
Intra-oral buccal view:
Objectives: to show the teeth in maximum intercuspation from the labial surface of the central
incisors to the distal of the first molar or the second molar
the occlusal plane parallel to the upper and lower edges of the frame
the frame should be filled with dental tissue not with lips, skin, fingers, or retractors
Subject: the patient seated upright in dental chair with the head turned as far as possible to the left
or right to make the job of the photographer more easier
Ask the patient to keep the tongue away from the teeth to help clear the photographing field from
saliva, keep an aspirator ready to clear excess saliva if necessary
Procedure: use a large retractor to pull the cheeks as far as distally away from the teeth to make
sure that distal surface of the molars can be recorded
Try to move perpendicular to a tangent to molar premolar area so that the sagittal discrepancy
will be fully represented on film
Upper occlusal view:
Objectives: the entire view finder should be filled with teeth showing the maxillary arch from 1-2
mm anterior to the labial surface of the central incisors to the distal of at least the 1st
molars, if the
2nd
molars erupted try to include them. The middle of the arch should be parallel to the dimension
of the frame
Subject: the patient should be seated upright on dental chair with the head and body tilted back
slightly. The mouth is wide open and the chin is tilted slightly toward the floor
The tongue should be held below the mirror to keep it out of view
The palatal surface of most of incisors should be visible
Procedure: the mirror shots are the hardest to take, at least one pair of hands and preferably two
are needed to help. Use retractor to pull the upper lip upward, laterally and forward. Ensure that
the lips are away from the labial surface of incisors
Keep the fingers and the retractors out of the shot and avoid a direct view to the tips of opposing
teeth
Warm the occlusal mirror in water for a few seconds then dry it by paper towel, before inserting
the mirror ask the patient to swallow to keep saliva away from the field of view

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Dr. Mohammed Alruby
Place the mirror in the mouth with the large end against the distal margin of the terminal molars,
press the mirror down onto the lower incisors and at this point the patient will tend to close so
usually reminded to open as much as possible
Ask the patient to breathe through the nose for a moment to reduce the fogging, the assistant should
ready to gently blow the air syringe on the mirror if it start to fog particularly at the maxillary
molar area
Angle the camera at 45 degree to the mirror which in turn is angled at 45 degree to the arch then
ask the patient to more open to allow taking the shot
Lower occlusal view:
Objectives: fill the view from anterior to labial surface of lower incisors to the distal of the 2nd
molars, the midline should be entered in the view
Subject: the patient seated with the body slightly tilted backward and the head tilted as far back as
possible. Ask the patient to place the tongue above and behind the mirror is possible
Procedure: this shot require an assistant. The lips are pulled downward, laterally and slightly
forward by retractor to show the mucosa as a background to the incisors
Try to avoid getting, fingers, retractors, or opposing incisors tip in the field of view
Use the same magnification in both upper and lower occlusal shots to allow comparison, have a
patient to open wide as possible and at the last moment move the distal end of the mirror slightly
away from the terminal molars
Common error in clinical photography:
Extra-oral shots:
1- Misrepresentation of skeletal pattern: this can occur if the patient tilts the head too far
backward or forward. Try to get every patient into FH plane or natural head position
2- Inconsistent magnification between stages of treatment, marks on the barrel of lens indicate
the proper positions for both intra-oral and extra-oral shots, the lens can be blocked at the
required magnification with a screw turned to finger tightness
Intra-oral shots:
1- Lack of symmetry: the occlusal plane should be horizontal and bisecting the frame, and the
clinically corrected midline should be right at the center of the slide. The viewfinder should
be filled with the teeth
2- Some of teeth out of focus: in intra-oral anterior shots, the focus should be in the lateral
incisors
In intra-oral buccal shots, the focus should be on the premolars, depth of field is not an
issue in mirror shots, since all the teeth are on the same plane
3- Backdrop of oral mucosa not provided: if the correct retractors are selected and the lips
are pulled not only laterally but forward, the oral mucosa rather than skin will be form a
background for all teeth in all views
4- Foreshortening: if the patient does not open wide enough for mirror shots, foreshortening
and arch distortion will occur. The occlusal mirror should be rested against the most distal
tooth in the arch being photographed, then placed on the opposing incisor tips
When ready to take a photograph, ask the patient to open twice as wide because the
variation in the size of dental arches
Always photograph the larger of the two arches first, filling the frame with teeth and keep
the same magnification for the smaller arch
5- Misrepresentation of sagittal discrepancy: when first taking orthodontic photographs, many
clinicians believe that sufficient retraction for buccal views will inflict undue pain on

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Dr. Mohammed Alruby
patients. The photographer must hold the retractor on the side being photographed, since
only he or she can pull that extra 5mm distally immediately before the shutter is occur
Photographic analysis:
For the analysis of the relationship between the craniofacial skeleton and the soft tissue facial
contours, profile and frontal photographs are taken under standard conditions
 Depending on the location of subnasal point relative to the skin nasion perpendicular there
are typical profile variation:
Average face: subnasal lying on the skin nasion perpendicular
Anteface: subnasal lying in front of the skin nasion perpendicular
Retroface: subnasal lying behind the skin nasion perpendicular
The clinical value of the photographic picture is that it is more realistic and gives a better record
of any changes in the soft tissue profile during the course of treatment which is a great advantage
 Another analysis based on the divergence of the face, the inclination between the two
reference lines is her analyzed
a- The line joining the forehead and the border of upper lip
b- The line joining the border of the upper lip and the soft tissue pogonion
The following profiles types are differentiated according to the relationship between
these two lines
Straight profile: the two lines form nearly a straight line
Convex profile: the two reference lines form an angle indicating a relative backward
displacement of the chin (posterior divergent)
Concave profile: the two reference lines form an angle indicating a relative forward
displacement of the chin (anterior divergent)
Frontal view: analysis of the frontal picture is important in assessing major disproportion and
asymmetries of the face in the transverse and vertical planes
For clinical analysis, it has proven practical to mark the two orbital points and to construct the
skin nasion perpendicular.
Basal metabolic rate (BMR)
Definition: minimum amount of energy required by the body to maintain life at complete physical
and mental rest in post absorptive state
Definition: amount of energy produced in unit time (one hour) under basal condition which are:
1- Complete physical and mental rest:
Patient must be comfortably in bed for ½ hour before the experiment, he should not sleep (this
lowers metabolism). Emotional stress should be avoided because:
- It produces sympathetic over-activity
- Increase metabolism
Basal arterial blood pressure and heart rate should be obtained, mental rest is important as
physical rest
2- Post-operative state:
This occurs 12-14 hours after the last meal, the digestive system is at rest. Last meal is at 7 pm and
measurements of BMR at 9 am next morning. This prevents the stimulating effect of food on
metabolic rate (MR)
3- Comfortable external temperature:

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The person should not feel cold or heat neither shivering nor sweeting, comfortable temperature
is 20 -25 degree for dressed persons and 28 -31 degree when naked
Basal metabolic rate expressed:
As the amount of heat (in calories) given by the body per square surface area /hour under basal
conditions
This BMR standard which differs with age and sex
Clinically BMR is expressed as % deviation from the normal standard. Normally BMR is -+15%
of standard value for the age and sex of the person
Basal metabolic rate represents:
Activity of heart, respiration, muscle, liver and skeletal muscle tone. It is the unavoidable cost of
life. It is not the minimal energy expenditure possible because it is reduced by many factors as
sleep
Measurements of BMR:
1- Direct calorimetry:
In which the heat produced by the person during a specified time is actually measured by use
apparatus called (body calorimeter)
It is an air tight and heat insulated room containing a bed for a person, the heat produced by the
person is absorbed by cold H2O running in metal tubes inside the apparatus
BMR = total amount of heat produced from the body in one hour / body surface area
2- Indirect calorimetry:
BMR: = O2 consumption / hour (liters) X 4.8 / body surface area
Normal value of BMR: 1600 cal /day in man and 1400 cal/day in women
N: B:
BMR is more related to body surface area because it is through the body surface that heat is lost
to the atmosphere
Factors affecting BMR:
- Physiological factors
- Pathological factors
- Chemical factors
A- Physiological factors:
1- Age:
Newly born infants: 25 c / H / m
2 –5 years : 60 c / H / m
Puberty: 55 c / H / m
20 years: 40 c / H / m
After 20 years: 1.0 cal decrease for every 10 years
2- Sex:
BMR is lower in females than males by 7%, this differences are not due to endocrine
differences because it is present in children, it may be due to greater stores of fat in females.
Fat has little metabolic activity
3- Physical habits:
Athletes have higher 10% BMR than ordinary persons, this due to their muscle bulk and
small store of fat

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Dr. Mohammed Alruby
4- Dietetic habits:
The habits of eating protein- rich diet for a long period increases BMR by 10% more than
eating carbohydrate
5- Climate:
BMR higher 10% in cold and temperature zones as Eskimo than in hot zones living in hot
countries decreases BMR 10%
6- Race:
Pure races as Chinese and Indian have lower BMR than mixed races as American and
Egyptian. Also dark races have lower BMR than white races
7- Sleep:
BMR is decreased by 10% during sleep due to decrease in muscle tone and sympathetic
activity
8- Pregnancy:
BMR gradually increases during pregnancy till it is doubled by its end. This is due to
increase in activity of thyroid gland and the added metabolism of fetus after delivery BMR
become normal
9- Starvation: during starvation; decrease in BMR up to 50% has been reported
B- Pathological factors:
Factors that increase BMR:
1- Hyperthyroidism:
Thyroxine is the most powerful stimulants for cell metabolism, so excess thyroxine secretion
is accompanied by a marked rise in the BMR up to 100% or even more
2- Hyperpitutarism:
Increase BMR by increasing the production of growth hormone which stimulate body
metabolism and of thyroid stimulation hormone which stimulate thyroxine production by
thyroid gland
3- Hyperadrenalism:
Tumors of supra-adrenal medulla are associated with attacks of marked increase in BMR
due to excessive formation of adrenaline by the tumor
4- Fever:
A raise of body temperature by 1 degree elevates BMR by 13%
5- Blood disease:
Over-activity of bone marrow or lymphatic tissues as in polycythemia, leukemia or anemia
cause marked increase in BMR
6- Heart failure:
The increase in BMR may be due to the increase in activity of respiratory muscles due to
dyspnea as difficulty in respiration, usually present
7- Diabetes insipidus:
(Marked increase in urine volume), the increase in BMR is to maintain body temperature
constant by raising the temperature of the large amounts of water taken orally since they
are usually at temperature lower than temperature of the lost volume of urine
Factors that decrease BMR:
1- Hypothyroidism: due to decrease in secretion of thyroxine
2- Hypopituitarism: due to atrophy of endocrine glans controlled by anterior pituitary gland
3- Hypo-function of adrenal cortex: due to decrease in secretion of corticoids which normally
stimulate metabolism

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Dr. Mohammed Alruby
4- Under-nutrition: lowered BMR is due to decreased production of endocrine secretions
(thyroxine, adrenaline and corticoids)
5- Hypothermia: drop of body temperature by 1 degree cause decrease in BMR by 13%
C- Chemical factors:
1- Thyroxine: is the most powerful physiological metabolic stimulants, 1m gm of it produce
100 degree
2- Adrenaline: increase BMR rapidly and for short period
3- Adenosine triphosphate: ATP: decrease BMR in severe hyperthyroidism
Electromyography EMG
Motor unit potential
Electromyography: A technique of recording of total electrical activity of motor nerve and the
muscle under study.
Electromyograph: Machine used to record graph
Electromyogram: record obtained
Benefits of EMG:
1- Allows to directly look into the muscle
2- Allows measurements of muscular performance
3- Helps in decision making both before and after surgery
4- Helps patient to find and train their muscles
5- Allows analysis to improve sports activities
During normal twitch of muscles fiber, a minute electrical potential is generated which dissipated
into surrounding tissue and hence can be detected on the skin above the muscle, the duration of
the action potential associated with this twitch is about 1-4 ms
Since all muscle
Fibers of a motor unit do not contract at exactly the same time. Some being delayed for several
milliseconds, the electrical potential developed by single twitch of all the fibers in the motor unit
is prolonged.
The electrical result of the motor unit twitch, there is an electrical discharge on motor unit potential
lasting about 5 -8 ms (and often as long as 12ms) the majority of these motor unit potentials have
an amplitude of around 0,5 mv
Motor unit potential may be detected by an electromyography which is a high g is a high gain
amplifier to which electrodes are connected. The electrodes The electrodes are placed either on
the skin above the muscle (skin electrode) or into the muscle needle. When motor unit potentials
obtained by electromyography are displayed on cathode ray oscilloscope
*** Factors affect the final size and pattern of individual motor unit potential that record:
1- Distance of unit frame
2- Electrodes
3- Types of electrodes
4- Equipment used
Clinical application of EMG:
1- Kinesiology: to assess degree and sequence of contraction of muscles in movements
2- Grading the force of muscular contraction

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Dr. Mohammed Alruby
3- At rest when normally there is no spontaneous muscle activity
4- Clinical diagnosis and follow up of neurogenic and myopathy disease
- Neurogenic disease: problem in nerve fibers
- Myopathy disease: problems in muscle fibers
EMG in different disease:
Neurogenic disease Myopathies
During rest Spontaneous activity (due to loss of
inhibitor)
No activity
Increase force of
contraction
Decrease number of motor unit but
surviving ones are bigger ( bigger
amplitude)
Decrease size of motor units
(amplitude and duration)
Maximum
contraction
Decrease interference pattern Decrease amplitude
duration and interference
According to Henneman principles (Henneman et al 1974) under normal condition, the
smaller potential appear first with slight contraction, as the force is increased larger and larger
potential are recruited, this being the normal pattern of recruitment. This normal pattern is absent
in case of partial paralysis due to injuries or lesions of lower motor neurons as: the small potential
nerve appears because only the larger motor unit have survived
Two common abnormalities that may be detected at rest when normal muscle is quiescent are
fibrillation and fasciculation:
1- Fibrillation:
- Contraction of single muscle cells which have become completely dissociated from nervous
control due to destruction of motor nerve and subsequent degeneration of the distal part of
the axon by disease or wilting of the nerve
- Fibrillation occurs for several weeks and then ceases as the muscle cell atrophy
- Not visible by naked eye
- Seen in neurogenic and myogenic disease so to find out fibrillation we perform EMG
2- Fasciculation:
- Contraction of group of muscle cells integrated by a single axon into a motor unit
- Occurs when an anterior motor neuron is destroyed, as in motor neuron disease or the axon
is severed
- Visible by naked eye
- Only seen in neurogenic disease