A 5-year-old boy (son of the patient in Case 98A) presented with muscle stiffness, finger swelling, diffuse erythema, pain in the wrist joints, and difficulty climbing stairs which started 3 months after his mother. On further questioning, his mother was diagnosed recognized that the erythema had been present for the past year.
Past medical history was negative.
His examination was unremarkable, except for a positive Gowers sign, although examination was limited due to poor cooperation, and manual muscle testing was difficult to do; gait was normal. He had erythema on the face, fingers, and knees ( Fig. 98B-1 ).
Fig. 98B-1
A , Patient in Case 98B showing erythema in the knuckles. B , The same patient showing erythema in the knees.
Laboratory studies revealed a creatine kinase of 35 IU/L (normal, 4–88 IU/L); erythrocyte sedimentation rate was 32 mm/h (normal, <20 mm/h); antinuclear antibodies were elevated with a 1/1280 titer. C3 was 92 mg/dL (normal, 89–173 mg/dL), and C4 was 21 mg/dL (normal, 17–42 mg/dL). Test for extractable nuclear antigens was normal. Human leukocyte antigen typing for DQA1, 01, and 02 was negative.
An EMG Test was Performed
Motor Nerve Studies
Nerve and Site
Latency (ms)
Amplitude (mV)
Conduction Velocity (m/s)
Median Nerve R.
Normal ≤ 4.2
Normal ≥ 6
Normal ≥ 50
Wrist
3.4
18
–
Elbow
8.0
18
55
Peroneal Nerve R.
Normal ≤ 5.7
Normal ≥ 3
Normal ≥ 40
Ankle
3.1
8
–
Fibular head
11.5
8
42
Knee
13.0
8
43
F-Wave Studies
Nerve
Latency (ms)
Normal Latency ≤ (ms)
Median nerve R.
26.8
30
Peroneal nerve R.
46.2
54
Sensory Nerve Studies
Nerve
Onset Latency (ms)
Normal Onset Latency ≤ (ms)
Peak Latency (ms)
Normal Peak Latency ≤ (ms)
Amp (μV)
Normal Amp ≥ (μV)
Conduction Velocity (m/s)
Normal Conduction Velocity ≥ (m/s)
Median nerve R.
2.1
2.6
2.6
3.1
40
20
62
50
Sural nerve R.
3.3
3.5
3.8
4.0
25
11
42
40
EMG Data
Muscle
Insrt Activity
Fibs
Pos Waves
Fasc
Amp
Dur
Poly
Pattern
Deltoid R.
None
None
None
None
Dec
Brief
Many
Full
Biceps brachii R.
None
None
None
None
Dec
Brief
Many
Full
Triceps R.
None
None
None
None
Dec
Brief
Few
Full
First dorsal interosseous R.
None
None
None
None
Norm
Norm
None
Full
Iliopsoas R.
None
None
None
None
Dec
Brief
Few
Full
Vastus lateralis R.
None
None
None
None
Dec
Brief
Few
Full
Only gold members can continue reading. Log In or Register to continue
A Man With Muscle Twitching and Poor Balance
A Woman With a Kingly Disease
A Diabetic Man With Bilateral Arm Weakness
A Woman With Rheumatoid Arthritis Who Developed Numbness and Pain in the Feet
A Man With Progressive Neuropathy and Congestive Heart Failure
A Woman With Droopy Eyelids and Difficulty Swallowing
