Vasculitic Tibial Mononeuropathy Associated with Inherited Immune Dysregulation: A Review of Tibial Mononeuropathies with Electrodiagnostic Considerations
Table 1
Electrodiagnostic data.
Nerve conduction
Amplitude (µV or mV)
Latency (ms)
Conduction velocity (m/s)
Right
Left
Right
Left
Right
Left
Sural sensory
Stimulate calf, record ankle (14 cm distance)
6.0 (6–47)
7.2 (6–47)
3.4 (3.2–4.2)
3.4 (3.2–4.2)
48.3 (>40)
53.8 (>40)
Medial plantar sensory
Stimulate foot, record ankle
No response
No response
—
—
—
—
Superficial peroneal sensory
Stimulate ankle, record foot (10 cm distance)
5.6
3.8
2.8
3.1
—
—
Peroneal motor
Stimulate ankle, record EDB (9 cm distance)
3.8 (2–12)
3.3 (2–12)
3.8 (3.3–6.1)
4.1 (3.3–6.1)
—
—
Stimulate below knee, record EDB
3.7
3.1
8.6
9.0
51.0 (41–56)
48.0 (41–56)
Stimulate above knee, record EDB
3.6
3.9
10.5
11.0
52.6
50.0
Tibial motor
Stimulate ankle, record AH (8 cm distance)
0.3 (3–26)
1.8 (3–26)
6.0 (2.7–6.1)
4.4 (2.7–6.1)
—
—
Temperatures: right calf: 34.8°C, left calf: 33.0°C
Needle electromyography
Spontaneous activity
Voluntary activity
Muscle (right)
Insertional activity
Positive sharp waves and fibrillations
Fasciculations
Amplitude
Duration
Polyphasia
Recruitment
FDIP
Increased
Sustained 3+
0
—
—
—
0
Anterior tibialis
Slightly increased
Unsustained 0
0
Normal
Increased 2+
Increased 2+
Decreased 3+
Medial gastrocnemius
Normal
0
0
Normal
Normal
Normal
Decreased 2+
Soleus
Increased
Sustained 2+
0
Normal
Increased 2+
Increased 2+
Decreased 3+
Short head of biceps
Normal
0
0
Normal
Normal
Normal
Normal
Gluteus medius
Normal
0
0
Normal
Normal
Normal
Normal
Nerve conduction studies: sensory study values are recorded in µV, and motor study values are recorded in mV. Note the markedly decreased amplitude of the right tibial motor response as compared with the left. Reference lab values are indictaed in parentheses. EDB = extensor digitorum brevis; AH = abductor hallucis. Needle electromyography: note the marked denervation of the soleus with relative sparing of the medial gastrocnemius and normal short head of the biceps. All voluntary activity was performed by the patient with normal effort. FDIP = first dorsal interosseous pedis.
