Foot Drop

Chief Complaint: A 45 year-old male presents with 1 week of foot drop with calf pain.

DOMAIN A: DATA ACQUISITION

+ What are the key components of this patient’s history and physical examination?

Relevant History:

  • What was the context and onset of these symptoms?
  • Was there any trauma or prior injury history?
  • Is the foot drop and pain unilateral or bilateral?
  • Has this ever happened before?
  • Please describe the quality, intensity, ?radiation, aggravating/alleviating factors of the pain.
  • Are there sensation changes, bowel or bladder changes, breathing difficulties, back or neck pain?
  • Has the patient been sick recently, or have any sick contacts?
  • Has the patient travelled recently?
  • Has the patient sought care for this problem before seeing me?
  • Does the patient have a known history of nerve or muscle disease?
  • Does the patient have a family history of nerve or muscle disease?
  • Functional history and current functional status, including equipment usage?
  • Past Medical and Surgical History?
  • Medications?
  • Allergies?

Relevant Physical Examination:

  • What are the vital signs?
  • Inspection for any asymmetry or deformities
  • Gait analysis
  • Palpation of bilateral lower extremities
  • Manual muscle testing, sensation to light touch and pinprick in bilateral lower extremities, reflexes in bilateral lower extremities
  • Integumentary exam of bilateral lower extremities

+ Challenge Question

  • Why are you asking about his travel and illness history?

+ Challenge Answer

  • The patient may have suffered from a recent infectious disease (upper respiratory or GI illness most commonly), or been exposed to individuals with communicable disease. Infectious diseases such as campylobacter can lead to Guillain Barre Syndrome (GBS/AIDP) which can present as an ascending paralysis, e.g. foot drop.
 

DOMAIN B: PROBLEM SOLVING

The patient is a 45 year-old male with no significant past medical history who presents with 1 week of right foot drop and right lateral calf/leg and dorsum of foot pain of gradual onset after camping and hiking in Colorado 1 week ago. He does not recall any recent illness, sick contacts, or particular injury, though the ground was unsteady at times. He complains of mild back pain upon further questioning. On examination, there is abnormal sensation to light touch over the lateral right leg below the knee and dorsum of the right foot. Manual muscle testing reveals 4/5 strength in right ankle dorsiflexion, great toe extension, and eversion. There is 2+ achilles reflex on the right side. The remainder of the bilateral lower extremity examination is normal.

+ What is your differential diagnosis for this patient?

  • Sciatic neuropathy, lumbosacral radiculopathy, lumbosacral plexopathy, common fibular neuropathy, deep fibular neuropathy, superficial fibular neuropathy, tibial neuropathy, Guillain Barre Syndrome / AIDP, Charcot-Marie-Tooth disease (CMT), cervical myelopathy, anterior horn cell disease, tarsal tunnel syndrome, dystonia, stroke, myopathy, compartment syndrome, multiple sclerosis (MS).

+ What is your next step?

  • Given the lack of infectious illness and unilaterality of symptoms, I do not favor a systemic process. In the context of intact hamstring strength and thigh sensation along with plantarflexion and posterior calf sensation, but impaired motor and sensory findings in the common fibular (peroneal) nerve distribution, I have suspicion of acute to subacute nerve impingement. Thus, I would obtain the following studies:
  • X-ray right knee
  • MRI right knee
  • If I possess diagnostic ultrasound skills in this scenario, then I would perform an in-office diagnostic ultrasound scan of the right knee and right lower extremity nerves during this visit.
  • I am not confident in the diagnostic yield of an EMG/nerve conduction study at this time, given the short duration of this patient’s symptoms (1 week).
 

+ Your next steps result in the following:

  • You opt to perform a diagnostic ultrasound scan of the right lower extremity during the office visit. It reveals the following:
  • Large, anechoic, compressible, round mass effacing the common fibular (peroneal) nerve near the fibular head/neck. Color doppler flow is negative within the mass. The mass appears to communicate with the superior tibiofibular joint.

DOMAIN C: PATIENT MANAGEMENT

+ How would you manage this patient?

  • During this visit I would educate the patient on my findings and show them images or video of what I suspect is a large intraneural common fibular/peroneal ganglion cyst in their leg compressing the common fibular/peroneal nerve and causing an impingement neuropathy of the common fibular/peroneal nerve, which is the likely explanation for their presenting complaints. I would educate that prompt cyst aspiration is indicated in order to preserve nerve function and promote functional recovery, and that this recovery can be expected to occur on the order of weeks to months. With informed consent obtained, I would proceed to perform an ultrasound-guided cyst drainage. If no contraindications, I would likely elect to inject corticosteroid into the cyst space following drainage in order to prevent cyst regrowth. Following drainage, I would recommend physical therapy and possibly an ankle-foot orthosis (AFO), depending on their gait analysis. I would recommend oral acetaminophen +/- NSAIDs for pain relief. If her symptoms returned, MRI of the leg would be appropriate with orthopedic surgery consult for surgical evaluation of cyst removal.
 

DOMAIN D: SYSTEMS-BASED PRACTICE

Your office lacks the proper equipment required to perform this cyst drainage. It is Friday morning and you are told there is no one else available in your region who can evaluate the patient today.

+ How would you proceed?

  • I would send the patient to the emergency department for prompt drainage with orthopedics consultation also obtained. I would call the ED ahead of time and relay all relevant clinical information to the emergency medicine physician, and would advise a consult to interventional radiology for stat cyst drainage. Time is nerve, and this situation of known nerve compression does require prompt drainage in order to relieve the source of compression on the common fibular/peroneal nerve. The more time that goes by, the more this nerve will be compressed and lead to further demyelination and axon loss, which will lead to a poorer functional recovery prognosis as time passes. Thus, it is necessary to address this known cyst today. I would discuss all of my recommendations with the patient, and ensure that all questions are answered and that he is agreeable to this plan.
 

DOMAIN E: INTERPERSONAL AND COMMUNICATION SKILLS

The patient is sent to the emergency department and undergoes cyst drainage. He calls your office 2 weeks later. Pretend that I am the patient.

Patient: “Doctor, my foot is still weak. You have to help me. I thought you said I could walk if we fix the nerve. Now I have a large ER bill and a weak foot, thanks to you.”

+ What is your response?

  • I am sorry to hear that your leg is still feeling weak. Unfortunately there was a large cyst compressing your sciatic nerve, as we discussed. We did have the cyst drained and the source of compression removed promptly. As discussed, nerves can take a long time to recover following an injury. They do possess the ability to sprout new connections, but also to regrow along the length of the nerve. This regrowth can take about 1 inch per month to occur. In your case, I would continue to expect recovery to occur in a span of weeks to months following the cyst drainage. I would like to see you back in the office in 2 weeks for a repeat ultrasound scan of your leg and nerve to make sure the cyst has not regrown. If you are not improving within another 2 weeks after that appointment, I would recommend a nerve test called and EMG/nerve conduction study, which will tell us about the health and function of that nerve, as well as the prognosis for recovery. I would also recommend potentially an MRI scan and orthopedics consult at that appointment to determine whether or not surgical removal of the cyst is required. What questions do you have for me? Does that plan sound all right with you?