SECTION 5: NERVOUS SYSTEM
INTRODUCTION
1. Nervous system involvement may result in multiple impairments, which should be combined using the Combined Values Chart.
2. Sensory impairment rating utilizes the Grading Scheme on page 60 for calculation of percent of impairment.
3. Sensory impairment is measured for the digits using two-point discrimination or pain/temperature, and for other regions using pain/temperature testing.
4. Two-point discrimination testing of the digits uses a varied series of one or two points applied. If the subject is unable to distinguish between one point and two points at a distance of at least 10mm in two out of three applications, then sensation is impaired.
5. Motor impairment rating utilizes the Grading Scheme on page 60 for calculation of permanent impairment.
CENTRAL NERVOUS SYSTEM (BRAIN AND SPINAL CORD)
1. Language Disturbances
% Impairment of Whole Person
a. Minimal disturbances in comprehension or expression of language symbols for daily living, with minimal impairment in functional communication
15%
b. Moderate impairment in comprehension or expression of language symbols for daily living, with some useful functional communication
30%
c. Severe impairment in comprehension or expression of language symbols for daily living, with little functional communication
75%
d. Inability to comprehend or express language symbols sufficient for daily living, with no functional communication
95%
2. Disturbances of Consciousness and/or Complex Integrated Cerebral Function. (Determined by medical observation and psychometric testing, excluding functional overlay or primary psychiatric disturbances.)
Disturbances of complex integrated cerebral function, include defects in orientation, thinking, memory, judgment, ability to initiate and perform planned activity, and social behavior. Disturbances of consciousness include lethargy, clouding of consciousness, delirium, stupor, coma, and persistent vegetative state
% Impairment of Whole Person
a. Mild impairment of complex integrated cerebral function, able to live independently
15%
b. Mild impairment of complex integrated cerebral function, able to live independently, but requiring supervision with executive function
30%
c. Moderate impairment of complex integrated cerebral function, demonstrated by psychometric testing, with mild disturbance of consciousness, but able to perform all activities of daily living with supervision on a daily basis
50%
d. Moderately severe impairment of complex integrated cerebral function or moderate disturbance of consciousness, requiring supervision for activities of daily living
75%
e. Severe impairment of complex integrated cerebral function or delirium, requiring assistance as well as supervision for activities of daily living
95%
f. Stupor, coma, or persistent vegetative state
99%
3. Emotional Disturbances (organic dysfunction documented by medical observation, supported by psychometric testing. Not primary psychiatric disturbances.)
% Impairment of Whole Person
a. Intermittent mild to moderate emotional disturbance under unusually stressful situations
15%
b. Mild to moderate emotional disturbance under ordinary stresses of daily living
30%
c. Moderate to severe emotional disturbance under ordinary stresses of daily living, requiring sheltered living
75%
d. Severe emotional disturbance that continually endangers self or others, requiring continuous supervision or protected care
95%
4. Episodic Neurological Disorders
% Impairment of Whole Person
a. Slight severity and under such control that most of the activities of daily living can be performed
10%
b. Of such severity as to interfere moderately with activities of daily living
30%
c. Of such severity and constancy as to limit activities to supervised or protected care or confinement in an institution
75%
d. Of such severity and constancy as to totally incapacitate the individual in terms of daily living
95%
5. Sleep and Arousal Disorders
% Impairment of Whole Person
a. Reduced daytime alertness due to sleepiness or sleep episodes or disturbed nocturnal sleep affecting complex cerebral functions, but ability remains to carry out most activities of daily living
15%
b. Reduced daytime alertness due to sleepiness or sleep episodes or disturbed nocturnal sleep affecting complex cerebral functions, requiring some supervision to carry out activities of daily living
30%
c. Reduced daytime alertness due to sleepiness or sleep episodes or disturbed nocturnal sleep that significantly limits activities of daily living, requiring supervision by caretakers
75%
d. Such a severe reduction of daytime alertness due to sleepiness or sleep episodes or disturbed nocturnal sleep so that activities of daily living are severely limited, individual is unable to care for self in any situation or manner
95%
6. Station and Gait/Mobility
% Impairment of Whole Person
a. Able to rise to standing position and walk, with or without assistive devices, independent at community level, except for difficulty with elevations, grades, stairs, and distances
10%
b. Able to rise to standing position and walk with or without assistive devices, and is independent at household but not community level
20%
c. Supervised standing and ambulation at household level
30%
d. Assisted ambulation, household level
40%
e. Nonambulatory, uses manual wheelchair, community level
65%
f. Nonambulatory, uses manual wheelchair, household level only
75%
g. Nonambulatory, uses power wheelchair only
85%
h. Nonambulatory, not able to use mobility device
95%
7. Use of the Upper Extremities
Preferred Extremity
Nonpreferred Extremity
Both Extremities
a. Can use the involved extremity for self-care, grasping and holding, but with difficulty with digital dexterity
10%
5%
15%
b. Can use the involved extremity for some self-care activities and can grasp and hold objects, with difficulty but without digital dexterity
30%
15%
50%
c. Can use the involved extremity for few self-care activities, with difficulty
40%
30%
70%
d. Unable to use involved extremity for any self-care activities
60%
40%
90%
8. Respiration
% Impairment of Whole Person
a. Capable of spontaneous respiration, with difficulty in activities of daily living that require exertion
20%
b. Capable of spontaneous respiration but to a degree that restricts functions such as standing, ambulation, and upper-extremity use
50%
c. Capable of spontaneous respiration, but to a degree that results in bed confinement
90%
d. No capacity for spontaneous respiration, requires a ventilator
95%
9. Urinary Bladder Function (organic bladder disorder)
% Impairment of Whole Person
a. Impairment in form of urgency
1 - 10%
b. Good reflex activity without voluntary control
11 - 20%
c. Poor reflex activity and no voluntary control
21 - 30%
d. No reflex or voluntary control
31 - 40%
10. Anorectal/Bowel Function (organic disorder)
% Impairment of Whole Person
a. Mild fecal incontinence
1 - 5%
b. Moderate but partial fecal incontinence
6 - 15%
c. Complete fecal incontinence
16 - 25%
11. Sexual Function (organic dysfunction)
% Impairment of Whole Person
a. Sexual function is possible, but with some degree of difficulty for erection or ejaculation in males, or awareness due to sensory loss in either sex.
10%
b. Reflex sexual function is possible, but without awareness due to sensory loss
20%
c. No capacity for sexual function
30%
SKULL DEFECTS
Unfilled Skull Defects
% Impairment of Whole Person
a. Up to 5 sq cm
1%
b. 6 – 10 sq cm
3%
c. 11 – 16 sq cm
5%
d. 17 – 26 sq cm
10%
e. 27 – 42 sq cm
15%
f. 43 or more sq cm
20%
SKULL DEFECTS
% Impairment of Whole Person
Skull fractures
0%
HEADACHES
% Impairment of Whole Person
Vascular, tension, or combination (if associated with neurologic or musculoskeletal condition of the head or neck, the primary condition may be ratable.)
0%
CRANIAL NERVES
1. Olfactory
% Impairment of Whole Person
a. Complete unilateral loss
0%
b. Complete bilateral loss
3%
2. Optic
% Impairment of Whole Person
a. Complete unilateral loss
24%
b. Complete bilateral loss
85%
3, 4, 5. Oculomotor, Trochlear, Abducens (alone or in combination)
% Impairment of Whole Person
Complete loss of ability to perceive single image but correctable by covering one eye
24%
6. Trigeminal
% Impairment of Whole Person
a. Complete unilateral sensory loss
10%
b. Complete bilateral sensory loss
35%
c. Intractable typical trigeminal neuralgia or tic douloureux
50%
d. Atypical facial neuralgia
20%
e. Complete unilateral motor loss
5%
f. Complete bilateral motor loss
30%
7. Facial
% Impairment of Whole Person
a. Complete loss of taste
3%
b. Complete unilateral paralysis
15%
c. Complete bilateral paralysis
45%
8. Auditory (See ENT Section)
9, 10. Glossopharyngeal or Vagus
% Impairment of Whole Person
a. Mild dysphagia with minimal modification of diet
10%
b. Moderate dysphagia with restriction to pureed food or liquid diet
30%
c. Feeding gastronomy or tube feeding required
50%
d. Dysarthria (See ENT Section)
11. Accessory (See spinal nerve affecting head and neck)
12. Hypoglossal
% Impairment of Whole Person
a. Unilateral paralysis
2%
b. Bilateral paralysis (see scale above for impaired swallowing)
1. Mild dysphagia with minimal modification of diet
2%
2. Moderate dysphagia with restriction to pureed food and/or thickened liquids
10%
3. Feeding gastronomy or tube feeding required
30%
4. Dysarthria (See ENT Section)
50%
SPINAL NERVE IMPAIRMENT AFFECTING HEAD AND NECK
Nerve
% Impairment of the Whole Person
Maximum % Loss of Function Due to Sensory Deficit, or Pain
Maximum % Loss of Function Due to Loss of Strength
Greater occipital
5%
0%
Lesser occipital
3%
0%
Greater articular
3%
0%
Spinal accessory
0%
10% unilateral
20% bilateral
(See Determination Procedures at the end of this section for grading schemes to determine whole-person impairment due to motor or sensory loss.)
THORACIC NERVES
Nerve
% Impairment of the Whole Person
Unilateral Involvement
Bilateral Involvement
Any 2 thoracic nerves
5%
10%
Any 2 – 5 thoracic nerves
10%
20%
Any 5 or more thoracic nerves
30%
50%
SPINAL NERVES AFFECTING INGUINAL REGION AND PERINEUM
Nerve
% Impairment of the Whole Person
Maximum % Loss of Function Due to Sensory Deficit, or Pain
Maximum % Loss of Function Due to Loss of Strength
Iliohypogastric
3%
0%
Ilioinguinal
5%
0%
Pudendal (unilateral)
5%
5%
Pudendal (bilateral)
20%
20%
Coccygeal
5%
0%
(See Determination Procedures at the end of this section for grading schemes to determine whole-person impairment due to motor or sensory loss.)
UNILATERAL SPINAL NERVE ROOT AFFECTING THE UPPER EXTREMITY
Nerve Root Impaired
% Impairment of the Whole Person
Maximum % Loss of Function Due to Sensory Deficit, or Pain
Maximum % Loss of Function Due to Motor Deficit or Loss of Power
C-5
5%
30%
C-6
8%
35%
C-7
5%
35%
C-8
5%
45%
T-1
5%
20%
(See Determination Procedures at the end of this section for grading schemes to determine the percentage of upper extremity. Convert upper-extremity impairment to whole-person only when all upper-extremity impairments have been combined.)
UNILATERAL BRACHIAL PLEXUS DISORDERS
Maximum % Loss of Function Due to Sensory Deficit, or Pain
Maximum % Loss of Function Due to Motor Deficit or Loss of Power
Brachial Plexus
100%
100%
Upper Trunk (C-5, C-6) (Duchenne-Erb)
25%
70%
Middle Trunk (C-7)
5%
35%
Lower Trunk (C-8, T-1) (Klumpke-Dejerine)
20%
70%
(See Determination Procedures at the end of this section for grading schemes to determine the percentage of upper extremity. Convert upper-extremity impairment to whole-person only when all upper-extremity impairments have been combined.)
SPECIFIC UNILATERAL SPINAL NERVE AFFECTING THE UPPER EXTREMITY
Nerve
Maximum % Loss of Function Due to Sensory Deficit, or Pain
Maximum % Loss of Function Due to Motor Deficit or Loss of Power
Anterior thoracic (pectoral)
0%
5%
Axillary (circumflex)
5%
35%
Dorsal scapular
0%
5%
Long thoracic (posterior thoracic n., external respiratory n. of Bell, n. to serratus anterior)
0%
15%
Medial antebrachial cutaneous
5%
0%
Medial brachial cutaneous
5%
0%
Median (above mid-forearm)
40%
55%
Median (below mid-forearm)
40%
35%
Branch to radial side of thumb
7%
0%
Branch to ulnar side of thumb
11%
0%
Branch to radial side of index finger
5%
0%
Branch to ulnar side of index finger
4%
0%
Branch to radial side of middle finger
5%
0%
Branch to ulnar side of middle finger
4%
0%
Branch to radial side of ring finger
3%
0%
Musculocutaneous
5%
25%
Radial (musculospiral) (upper arm with loss of triceps) wrist placed in position of function
5%
55%
Radial (musculospiral) (with sparing of triceps) wrist placed in position of function
5%
40%
Subscapular (upper and lower)
0%
5%
Suprascapular
5%
15%
Thoracodorsal (long subscapular; nerve to latissimus dorsi)
0%
10%
Ulnar (above mid-forearm)
10%
35%
Ulnar (below mid-forearm)
10%
25%
Branch to ulnar side of ring finger
2%
0%
Branch to radial side of little finger
3%
0%
Branch to ulnar side of little finger
3%
0%
(See Determination Procedures at the end of this section for grading schemes to determine the percentage of upper extremity. Convert upper-extremity impairment to whole-person only when all upper-extremity impairments have been combined.)
UPPER EXTREMITY DUE TO ENTRAPMENT NEUROPATHY
UNILATERAL SPINAL NERVE ROOT AFFECTING THE LOWER EXTREMITY
Nerve Root Impaired
Maximum % Loss of Function Due to Sensory Deficit, or Pain
Maximum % Loss of Function Due to Loss of Strength
L-3
5%
20%
L-4
5%
34%
L-5
5%
37%
S-1
5%
20%
(See Determination Procedures at the end of this section for grading schemes to determine the percentage of lower extremity. Convert lower-extremity impairment to whole-person only when all lower-extremity impairments have been combined.)
UNILATERAL LUMBOSACRAL PLEXUS
Maximum % Loss of Function Due to Sensory Deficit, or Pain
Maximum % Loss of Function Due to Loss of Strength
Lumbosacral Plexus
40%
50%
(See Determination Procedures at the end of this section for grading schemes to determine the percentage of lower extremity. Convert lower-extremity impairment to whole-person only when all lower-extremity impairments have been combined.)
SPECIFIC UNILATERAL SPINAL NERVE AFFECTING THE LOWER EXTREMITY
Nerve
Maximum % Loss of Function Due to Sensory Deficit, or Pain
Maximum % Loss of Function Due to Motor Deficit or Loss of Power
Femoral (anterior crural)
5%
35%
Femoral (anterior Crural) (below iliacus nerve)
5%
30%
Genitofemoral (genito crural)
5%
0%
Inferior gluteal
0%
25%
Lateral femoral cutaneous
10%
0%
N. to obturator internus muscle
N. to piriformis muscle
0%
10%
N. to quadratus femoris muscle
N. to superior gemellus muscle Obturator
0%
10%
Posterior cutaneous of thigh
5%
0%
Superior gluteal
0%
20%
Sciatic (above hamstring innervation)
25%
75%
Common peroneal (lateral, or external popliteal)
5%
35%
Deep (above mid-shin)
Deep (below mid-shin)
0%
25%
Anterior tibial
0%
5%
Superficial
5%
10%
Tibial nerve (medial, or internal popliteal)
Above knee
15%
35%
Posterior tibial (mid-calf and knee)
15%
25%
Below mid-calf
15%
15%
Lateral plantar branch
5%
5%
Medial plantar branch
5%
5%
Sural (external Saphenous)
5%
0%
DETERMINATION OF PAIN OR LOSS OF SENSATION
Grading Scheme
Description ... Grade
1. No loss of sensation or no spontaneous abnormal sensations ... 0%
2. Impaired sensation with or without pain, which does not interfere with activity ... 1—15%
3. Impaired sensation with or without pain, which interferes with activity ... 16—30%
4. Impaired sensation with or without pain, which may prevent activity ... 31—60%
5. Impaired sensation with or without severe pain, which prevents activity ... 61—90%
6. Impaired sensation with or without pain, which prevents all activity ... 91—100%
Procedure for determining Impairment Due to Sensory Involvement
1. Identify area of involvement using appropriate anatomical chart.
2. Identify the nerve(s) or root level(s) for the involved area.
3. Find the value for the maximum loss of function of the nerve(s) or root(s), due to pain or loss of sensation, using the appropriate table.
4. Grade the degree of impaired sensation or pain according to the Grading Scheme.
5. Multiply the value of the nerve or root by the degree of impaired sensation or pain.
DETERMINATION OF STRENGTH (POWER) AND/OR MOTOR DEFICIT
Grading Scheme
Description ... Grade
1. Range of motion against gravity and full resistance (normal strength) ... 0%
2. Range of motion against gravity and some resistance, or reduced fine movements and motor control, may include abnormalities documented by electrophysiological studies (good strength) ... 1 – 40%
3. Range of motion against gravity, but without resistance (fair strength) ... 41 – 60%
4. Range of motion with gravity eliminated (poor strength) ... 61 – 75%
5. Slight palpable muscle contraction (trace strength) ... 76 – 99%
6. No contractibility and no muscle function (zero strength) ... 100%
Procedure for determining Impairment Due to Motor Involvement
1. Identify the motion involved
2. Identify the muscle(s) performing the function
3. Determine the nerve(s) that innervate the involved muscle(s) and find the value for maximum percentage loss due to loss of strength or power, according to the appropriate table.
4. Grade the degree of loss of strength or power according to the Grading Scheme.
5. Multiply the value of the nerve by the degree of loss of strength or power.