Denouement Hot Seat #14: Abnormal Gait

by Priya Gopwani with Jamil Madati on the Hot Seat
 
This is a case of a 3 year-old with progressive abnormal gait, toe-walking, and elevated inflammatory markers with normal lower extremity x-rays.
 
Thank you to Dewesh, Sabah, Theresa, Paul, Rasha, and Moh for their analysis and clinical reasoning. Please click here to read through their perspectives and approaches (scroll up).
 
Here's how you answered our questions: 
1. Given your abnormal findings as above, what you would like to image further?

2. How would you like to proceed with your further imaging?

3. Should this patient be admitted? They seem reliable and it is not a holiday weekend

Hot Seat Response
by Jamil Madati

Thanks Priya for an extremely intriguing and challenging case (remind me to pay you back some day). Had me going back and forth between 3-4 different diagnoses. With that said, having no clear, “slam dunk” diagnosis in mind, I’d try a logical, methodical approach, making sure to address the key historical and physical exam factors that could suggest a worrisome (life threatening, limb/organ threatening) diagnoses, and leave it to the inpatient subspecialists to figure out the final answer.

In a nutshell, the thing that gets me concerned about this kid is that he has had 2-3 weeks of intermittent and migratory leg pain resulting in limp that has now progressed to inability to get up from sitting and toe walking. The differential diagnoses for abnormal gait is broad, but given that this patient has had, no history of trauma, normal musculo-skeletal exam, Xrays that were negative, it makes skeletal abnormalities not likely. The history of viral illness several weeks ago making transient synovitis possible but those kids definitely don’t toe walk. Post viral myositis can present with muscle belly tenderness that sometimes can be migratory and is usually preceded by a viral syndrome BUT you shouldn’t get any neurologic symptoms. The H&P seem to point to both a neurologic and a muscular disease process leading me to think of some sort of... (wait for it) ‘neuro-muscular’ disease process.
 
The description of getting up from sitting to standing, sounds like a classic Gower’s sign which is seen in kids that present with Duchenne’s Muscular Dystrophy (can be seen as early as 3 year olds but usually is more notable in kids ~5-7year old and is a result of progressive hip/gluteal muscle weakness). Classic DMD patients would also have pseudohypertrophy of calf muscles on PE (due to fatty infiltration as well as muscle fiber hypertrophy), which is not mentioned in our exam. But normal CK makes DMD less likely!
The toe walking in a previously normal kid needs a brief discussion. From benign to more severe: toe walking can be behavioral (easily extinguishes). Toe walking can also result from shortened or tight Achilles tendons. Your PE would show resistance/stiffness with dorsiflexion. In the ED, we usually see toe walking as a result of spastic CP from perinatal anoxic injury. I would expect to have a history of toe walking from when they started walking (as opposed to several years after the onset of walking). On PE, CP patients should have ankle clonus when testing reflexes. Lastly, toe walking can be seen in kids with muscular dystrophy, which would make me think about getting neuro consult, given that this diagnosis is a distinct possibility.
 
Getting back to the case, I put this kid in a category progressive painful neurologic and muscular disease process with concerning abnormalities noted on neurologic exam making me uncomfortable sending this kid home without some sort of imaging or neurology consult. My biggest fear is ruling out something in the lower spinal cord that is causing this relatively acute onset spasticity and hyperreflexia +/- weakness (Gower’s). Dewesh and Sabah’s comments astutely brought up the possibility of tethered cord, the possible diagnosis of epidural abscess because of abnl labs or the possibility of malignancy compressing the spinal cord. Other possibilities include syringomyelia, myelomeningocele (given the V shaped gluteal cleft possibly suggesting underlying undiagnosed congenital neural tube defect) or some sort of spinal cord stenosis that is now symptomatic. 

Because on-going compression or injury to the spinal cord is a possibility, I would push for emergent imaging (MRI) of the spinal cord that same evening (not as worried about the brain given the neuro exam reported). Definitely get a Neuro consult and I would also strongly push for an inpatient (rather than ED or outpatient) evaluation of this patient since his neurologic symptoms appear to be static or possibly progressive in nature.
 
The Denouement
by Priya Gopwani
 
The patient was admitted to the Neurology service to expedite MRI imaging. The neurologists were not convinced of the hyper-reflexing R patella, but agreed with the remainder of the exam as previously described. They obtained an MRI of the pelvis and lower extremities, on which there was an increased signal noted in the left acetabulum on fluid-sensitive and contrast-enhanced sequences with decreased signal on T1s in the same location. No focal fluid collection or hip effusion was seen. This MRI was concerning for osteomyelitis vs malignancy (metastasis).

The patient then underwent CT-guided biopsy of the lesion. CT of the lesion revealed a spherical lytic bone lesion in the medial third of the iliac bone forming the acetabular roof, measuring 15cm in diameter. There was no periosteal reaction or soft tissue mass identified. A biopsy was obtained and revealed slightly reactive bone with mild increase in lymphoplasmacytic infiltrate. There was no distinct evidence of malignancy, and abdominal ultrasound was normal. This made a diagnosis of chronic osteomyelitis more likely. Cultures grew out sparse colonies of Micrococcus, which ID believes is a contaminant. The patient was diagnosed with presumed chronic osteomyelitis and is currently being treated with IV clindamycin.

Update:
The patient re-presented to the ER recently due to a fall at home and worsening pain. As it turns out, the lesion is actually not chronic osteo but an eosinophilic granuloma (they changed the biopsy result). Getting a repeat biopsy this week to confirm.

The Hot Seat is a recurrent online case series aimed at facilitating asynchronous sharing of PEM knowledge and experience. Faculty are placed on The Hot Seat and publish their opinions without knowing the case or its outcomes. Cases are all actual cases and are written by PEM fellows at Children's National in Washington, DC. Emily Willner is the faculty advisor on case presentations. We welcome your commentary.