Basic Human Neuroanatomy
A Clinically Oriented Atlas 
Case 117 Answers

1. Does this patient's weakness suggest an upper motor neuron or lower motor neuron process?

Lower motor neuron (LMN) process.

2. This patient experienced a variety of abnormal sensory signs and symptoms. List the terms relating to these sensory phenomena, along with their definitions or descriptions.

Hypalgesia: Decreased sensitivity to painful stimuli.

Hypesthesia (hypoesthesia): Decreased sensitivity to touch/pressure stimuli, usually described as numbness.

Paresthesia: Spontaneous abnormal sensation that is not unpleasant, usually described as tingling or “pins and needles”.

Dysesthesia: Spontaneous abnormal sensation that is unpleasant to the patient (e.g., unpleasant tingling, pins and needles, burning).

Allodynia: Abnormal perception of pain from a normally nonpainful stimulus (e.g., simple touch or mild pressure).

Hyperalgesia: Exaggerated pain response from a normally painful stimulus.

Hyperpathia: Abnormally exaggerated, painful, and distressing reaction to a painful stimulus.

Neuralgic pain: Pain that is described as sharp, stabbing, shooting, or lancinating in nature.

3. Is there evidence of spinal cord involvement in this case and, if so, at what level?


4. Is there evidence of dorsal or ventral root involvement or spinal nerve involvement in this case, and, if so, what is the level(s) of the involvement?

No. The patient’s motor and sensory signs and symptoms do not follow a specific dermatomal or myotomal pattern.

5. Is there evidence of plexus or peripheral nerve involvement in this case? If so, indicate the specific structure(s) involved by the pathologic process.

Yes. The patient’s signs and symptoms suggest involvement of a specific peripheral nerve of the left sacral plexus, the common fibular (peroneal) nerve, while sparing other nerves of the plexus (e.g., the tibial nerve and more proximal nerves of the plexus). Numbness, tingling, and sharp, stabbing and shooting pain involving the anterolateral aspect of the leg, dorsum of the foot, and the dorsal surface of the first 4 toes, plus the weakness of ankle dorsiflexion, inversion and eversion of the foot, and extension of the toes, suggest a lesion of the left common fibular (peroneal) nerve, involving both the superficial and deep fibular (peroneal) nerves.

6. Where is the anatomical location of the pathologic process leading to this patient’s condition?

Her common fibular (peroneal) mononeuropathy appears to be localized to the region near the head of the fibula where the nerve winds around the neck of the fibula, passes deep to the fibularis (peroneus) longus muscle, and divides into the superficial fibular (peroneal) and deep fibular (peroneal) nerves. This is a common site of compression of the fibular (peroneal) nerves.

7. In general, what type of pathological process do you think is involved in this case?

The most likely pathological process in this setting is a compression or pressure neuropathy due to the direct trauma to the nerve when the car door was pressed against her left leg just below the knee.

8. What diagnostic procedure(s) would you undertake at this point? 

Click here for images

Website Builder