SpineUniverse Case Study Library

Sudden Right Foot Drop after Skiing


The patient, aged 54-years, is an avid skier and mountain biker who presents with a sudden right foot drop after skiing. She had a transient left leg radiculopathy that improved with a bilateral L4-L5, L5-S1 transforaminal epidural steroid injection. However, persistent weakness in right ankle dorsiflexion has prevented her from returning to her activities.

Her history includes degenerative scoliosis, which has been well-managed with nonoperative care. Previously (2012), she underwent right L4-L5 microdisectomy.


The patient is pleasant, appropriate to the situation, interactive and a reliable historian.

musculoskeletal examination, lower extremities

  • Sensation to light touch is decreased, right lateral calf
  • Reflexes (R/L): 1+/1+ knees and 0/1+ankles
  • Straight leg raise (SLR): Negative bilaterally
  • Hip range of motion: No reproduction of pain
  • No atrophy of the quadriceps or gastrocsoleus
  • No edema
  • Pulses (R/L): 2+/2+ posterior tibial

Pretreatment Imaging

Anteroposterior (Figure 1A) and lateral (Figure 1B) x-rays of the lumbar spine.

Anteroposterior and lateral x-rays of the lumbar spineFigures 1A and 1B. Image courtesy of Choll W. Kim, MD, and SpineUniverse.com.

Flexion (Figure 2A) and extension (Figure 2B) x-rays of the lumbar spine.

Flexion and extension of the lumbar spineFigures 2A and 2B. Image courtesy of Choll W. Kim, MD, and SpineUniverse.com.

Sagittal MRI (Figure 3A) denotes L4; Figure 3B is an axial view of L4-L5.

Sagittal view of L4 and axial view of L4-L5Figures 3A and 3B. Image courtesy of Choll W. Kim, MD, and SpineUniverse.com.

Sagittal MRI denotes the L5 level (Figure 4A) and corresponding axial view of L5 (Figure 4B).

Sagittal MRI of L5 level and axial view of L5Figures 4A and 4B. Image courtesy of Choll W. Kim, MD, and SpineUniverse.com.


Recurrent L4-L5 herniated nucleus pulposus with right foot drop.

Suggest Treatment

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Selected Treatment

Right L4-L5 transforaminal endoscopic discectomy was performed.

Surgeon's Treatment Rationale
The patient is regularly active and maintains a high level of function. Surgical decision-making was focused on treating the acute problem of motor weakness due to the disc herniation while simultaneously allowing for a rapid recovery and return to activities. Her underlying scoliosis is a long-standing problem that has been managed nonoperatively, and the goal was to continue nonoperative treatment of this more extensive problem.

Procedure Description
The initial dilator is placed along the posterior annulus, within the canal (Figures 5A and 5B).

Intracanal technique, placement for intial dilator into the epidural spaceFigures 5A and 5B. Intracanal technique; placement for the initial dilator into the epidural space. Image courtesy of Choll W. Kim, MD, and SpineUniverse.com. Serial dilation is performed along with reaming to open the neuroforamen. The working cannula is then positioned to visualize the epidural space and annulus.

Disc fragments (stained with Indigo Carmine; see Figure 7B below) are identified and removed with pituitary ronguers. Straight and angled graspers are then used to pull out herniated disc fragments. Frayed edges of the annular tear are ablated using the Ellman radiofrequency probe and YAG holmium side-firing laser (Figures 6A, 6B, video) to complete the discectomy.

Disc fragments are identified and removed using straight and angled graspersFigures 6A and 6B.Image courtesy of Choll W. Kim, MD, and SpineUniverse.com.

Surgical Video

The decompression is assessed by visualizing the traversing and exiting nerve roots, and probing the canal with the curved ball-tip probe (Figure 7A). The probe is observed to pass easily through the path of the exiting nerve root, across the midline of the canal, and down the path of the traversing nerve root, past the pedicle.

Ball-tip probe used to assess exiting nerve rootsFigures 7A and 7B. Image courtesy of Choll W. Kim, MD, and SpineUniverse.com. Dr. Kim's laser endoscopic spine surgery website explains the procedure in more detail.


The patient reported she has, "practically no foot drop while walking."

preoperature versus postoperative sagittal MRIFigures 8A and 8B. Image courtesy of Choll W. Kim, MD, and SpineUniverse.com.

musculoskeletal examination, lower extremities, preoperative versus postoperative

  • ODI: 10
  • VAS Back: 0
  • VAS Right Leg: 2-3
  • VAS Left Leg: 0


Case Discussion

Dr. Kim details the case of a patient with an L5 radiculopathy who presents primarily with weakness as opposed to pain. She failed a course of nonoperative therapy. Previously, she had a L4-L5 microdiscectomy.

Her imaging studies demonstrate a tremendous loss in lumbar lordosis, as well as a coronal plane deformity. There is no instability on the dynamic films. The patient was successfully treated with an endoscopic discectomy on the right at L4-L5. She made an excellent recovery in terms of motor function, but the date of follow-up is not provided.

This is an excellent case to consider. Although her imaging studies clearly show her spinal alignment is suboptimal, she does not have back pain and only presents with a radiculopathy. Therefore, Dr. Kim's choice to treat only the radiculopathy is most appropriate. It would be completely unreasonable to perform a major realignment and reconstruction at this point in time. Unfortunately, for this woman, at some point in her life, she will probably require more extensive surgery. However, as time passes, the techniques will improve and as that occurs, one would expect the risk of complication to decrease. Therefore, to allow her to be fully active at this time without a large fusion is the best choice.

Many surgeons do not use the endoscope and prefer to do these procedures using a minimally invasive approach with the microscope. This allows for true 3-D visualization and decreases the need for extra equipment in the operating room. Using either of these techniques has been reported to result in excellent outcomes. The key point of the specific surgical technique is that it helps preserve the supporting structures due to its minimally invasive nature.

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