Case 27
HISTORY AND PHYSICAL EXAMINATION
| Right | Left | |
|---|---|---|
| Shoulder abduction | 5/5 | 5/5 |
| Elbow flexion | 5/5 | 5/5 |
| Elbow extension | 2/5 | 5/5 |
| Pronation | 0/5 | 2/5 |
| Finger flexion (digits 1, 2, and 3) | 0/5 | 0/5 |
| Finger flexion (digits 4 and 5) | 0/5 | 4+/5 |
| Wrist flexion | 0/5 | 2/5 |
| Wrist extension | 0/5 | 5/5 |
| Finger extension | 0/5 | 4+/5 |
| Finger abduction | 0/5 | 4+/5 |
| Right | Left | |
| Hip flexion | 5/5 | 5/5 |
| Hip extension | 5/5 | 5/5 |
| Knee extension | 4+/5 | 4+/5 |
| Knee flexion | 4+/5 | 4+/5 |
| Foot dorsiflexion | 0/5 | 4−/5 |
| Toe dorsiflexion | 0/5 | 0/5 |
| Plantar flexion | 0/5 | 4/5 |
| Ankle inversion | 0/5 | 0/5 |
| Ankle eversion | 0/5 | 0/5 |
Sensation revealed a stocking glove distribution bilaterally with no clear asymmetry. There was no clear sensory loss in the left median distribution compared to the ulnar distribution on formal testing. The deep tendon reflexes were +2 at the biceps bilaterally, +2 at the left triceps, and absent at the right triceps, and absent at the brachioradialis bilaterally. The knee jerks were +1 bilaterally, while the ankle jerks were absent. Plantar responses are both flexors. Gait was not examined.
Please now review the Nerve Conduction Studies and Needle EMG tables.
QUESTIONS
EDX FINDINGS AND INTERPRETATION OF DATA
The relevant EDX findings in this case include:
1. Absent routine sensory nerve action potentials (SNAPs) and routine compound muscle action potentials (CMAPs) in both lower extremities. This finding is consistent with a generalized axon-loss disorder affecting the sensory and motor fibers, such as a sensorimotor peripheral polyneuropathy.
2. Asymmetrical peroneal motor nerve conduction studies (NCSs), recording tibialis anterior, in the lower extremities. The responses were absent on the right while they were evoked with low CMAP amplitudes on the left with no conduction block or slowing of distal latency and minimal slowing of conduction velocity. This finding suggests that the disorder is asymmetrical.
3. Absent routine sensory and motor conduction studies in the right upper extremity while the left upper extremity showed absent median sensory and motor conduction studies and only borderline or slightly reduced ulnar and radial SNAP amplitudes and ulnar motor CMAP amplitude with normal distal latency, conduction velocity and F wave minimal latency. This is a very useful finding; it points to a severe left median mononeuropathy as well as an asymmetrical polyneuropathy in the upper extremities. The left median mononeuropathy could not be localized since the median motor and sensory responses were absent. Hence, a remote left carpal tunnel cannot be excluded at this point.
4. The needle examination confirms several important findings. First, the severe left median mononeuropathy is at or above the elbow as evidenced by the severe active denervation and loss of motor unit action potentials (MUAPs) of all sampled median innervated muscles in the left hand and forearm, including the pronator teres. Second, the active denervation and loss of MUAPs is asymmetrical, as noted mostly in the distal upper extremities (much worse on the right, excluding the left median nerve), but also slightly in the lower extremities (much severe denervation of the right tibialis anterior and medial gastrocnemius than the left). Third, the active denervation and loss of MUAPs in the right upper extremity suggests either overlapping and combined right median, ulnar, and radial mononeuropathies or a right middle and lower trunk brachial plexopathy. Fourth, the prominent fibrillation potentials are supportive evidence for ongoing (active) denervation.
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