Orthopedics Today Grand Rounds

A 5-year-old boy with paresthesias, weakness and ataxia

A 5-year-old boy from Cypress presented with a few months of progressive upper and lower extremity paresthesias, weakness and ataxia. His mother contributed to the pertinent history. She denied any significant trauma but said her son had been falling a lot recently. The boy described numbness and tingling in his hands and feet. He also had a lot more trouble playing with his toys and seemed to drop objects frequently. The patient’s mother denied any episodes of bowel or bladder incontinence.

The child’s mother reported a past medical history that was significant for a genetic syndrome characterized by bilateral dislocated knees and clubfeet. The patient required multiple knee and foot procedures as an infant. Since then, however, he had been ambulating unassisted. He did not have any additional medical comorbidities and took no medications. The patient had no known drug allergies.

On exam, the patient had a shortened stature for his age, prominent forehead, flattened nasal bridge and wide-set eyes. He had significant clubfoot deformities bilaterally. He had full strength in his bilateral upper and lower extremities. He had hyperreflexia in his bilateral upper and lower extremities with a few intermittent beats of clonus. He had a positive Hoffman’s sign bilaterally and had an ataxic gait.

Plain radiographs of the cervical spine were obtained. They demonstrated severe cervical kyphosis. CT of the cervical spine obtained to further evaluate the deformity revealed a cervical kyphosis angle of 75° across C4-C6 with a hypoplastic C5 vertebral body, as well as anteroposterior (AP) dissociation of C2-T1 due to pars defects at those levels. MRI of the cervical spine without IV contrast was obtained, which revealed significant spinal cord compression with myelomalacia at C5 (Figure 1). A 3-D CT reconstruction was done of the patient’s deformity (Figure 2).

cervical CT and MRI images
Figure 1. Representative cervical CT (a) and MRI (b) images in the sagittal plane demonstrate the extent of cervical kyphosis and associated spinal cord compression with myelomalacia, respectively.
Figure 2. Representative 3-D reconstruction of a cervical CT scan further demonstrates the patient’s severe kyphotic deformity.

Source: Joshua M. Pahys, MD

What is your diagnosis?

See answer on next page.

Progressive myelopathy due to severe cervical kyphosis in a patient with Larsen syndrome

Due to the progressive myelopathy (ataxia, hyperreflexia) and imaging to confirm the diagnosis, staged AP surgery was recommended to correct the patient’s deformity, stabilize the cervical spine and prevent further progression of his myelopathy. Given that his myelopathy was present for a few months prior to his evaluation, the likelihood of complete resolution of his symptoms was encouraging, but not guaranteed. The parents provided appropriate consent for the procedure. The patient was admitted to the hospital 2 weeks prior to his scheduled procedures and was placed in halo gravity traction to reduce the cervical kyphosis.

The patient then underwent the anterior portion of the staged procedures. Given that the patient had evidence of anteroposterior dissociation of C2-T1 on preoperative imaging, the plan was to extend the fusion through those segments after correcting his alignment. Using a standard Smith-Robinson approach, the anterior cervical spine was exposed and discectomies were performed from C2-T1 in standard fashion. There was significant anterior scar/fibrotic tissue anterior to C5 that was about 1-cm deep, which was dissected through in a layered fashion. Fluoroscopy was used throughout the dissection to confirm the depth. Due to the significant kyphosis from C4-C6, it was elected to perform C5 and C6 corpectomies. Two Caspar pins were placed, one each into C4 and C7, to manipulate the cervical spine into more neutral or lordotic alignment. Despite the gentle traction, the Caspar pins were unable to reasonably realign C4 out of kyphotic angulation and it was decided to remove the body of C4, as well. After performing a corpectomy of C4, Caspar pins were placed into C3 and C7, and gentle distraction was performed to attain proper cervical alignment and reduce the patient’s severe kyphosis back to a neutral alignment. A 9-mm x 40-mm fibular strut graft was carefully malleted into place between C3 and C7. The portions of autograft bone that had been removed from the corpectomy were then gently tamped into place in the C2-C3 interspace. An allograft plug was then gently malleted into the C7-T1 interspace. The properly-sized plate was then assessed using calipers. Given the small size of the patient’s vertebral bodies, no plates were available in a size to allow placement of screws into both C7 and T1. Thus, it was elected to place screws into C3 and T1. The plate was not extended up to C2 due to concern for implant prominence at this level and possible associated morbidity (Figure 3). Postoperatively, the patient was placed in a halo vest to provide additional provisional stabilization prior to his staged posterior fusion.

Postoperative plain cervical radiographs
Figure 3. Postoperative AP (a) and lateral (b) plain cervical radiographs show corrected cervical alignment to neutral.

One week later, the patient underwent completion of his staged procedure. A standard posterior, cervical, longitudinal midline incision was made overlying the spinous processes of C2-T2. Subperiosteal dissection of the posterior elements was carried out to the lateral aspects of the lateral masses from C2-T2. There was significant mobility of the posterior elements from C2-T1 secondary to the patient’s pars defects. The pars defects made it unsafe to place pedicle screws at C2, so a Gill laminectomy was performed bilaterally at C2. A significant amount of scar tissue was removed from the site of the pars defects. Bilateral C2 pedicle screws were placed with the guidance of C-arm fluoroscopy as well as anatomic landmarks. Four lateral mass screws were placed bilaterally at C3 and C5. Levels C6 and C7 did not appear able to accommodate a screw and thus were left empty. Level T1 was then evaluated. A small laminotomy was performed which revealed a pedicle less than 2 mm in size, which was not amenable to safe cannulation. Thus, this level was left empty, as well. Bilateral T2 pedicle screws were then placed with guidance from C-arm fluoroscopy and the anatomic landmarks. Two rods were measured and secured in placed bilaterally. Proper alignment was checked and confirmed using biplanar fluoroscopy. The posterior elements were thoroughly decorticated using a high-speed bur. A mix of 10 mL of autograft, 15 mL of crushed cancellous allograft and 10 mL demineralized bone matrix was made and packed in the decorticated portion of the wound.

Crosslinks were measured and placed at T1 on the rod and a head-to-head crosslink was placed across C2. After closure, the patient was placed back in a halo vest, which he was to wear for 6 weeks postoperatively.

Discussion

The patient presented herein developed severe cervical kyphosis leading to progressive myelopathy due to his underlying Larsen syndrome, which is a rare genetic disorder that results from a genetic mutation in the FLNB gene. It is produces filamin B, a crucial protein that makes up part of the cytoskeleton of cells and has a prominent role in the development of the skeleton in utero. Therefore, patients with Larsen syndrome can be born with clubfeet, dislocations of the hips, knees or elbows, and hypermobility of multiple joints. Spinal instability and cervical kyphosis are additional potential concerns for these patients.

Fewer than 15 cases of severe progressive cervical kyphosis in patients with Larsen syndrome have been reported. All children with this disorder should receive regular screening cervical radiographs at their initial visit. If cervical kyphosis is noted on plain radiographs, CT and MRI are recommended as many of these patients also have complete AP dissociation of the cervical spine.

Surgical intervention is generally recommended prior to the development of severe kyphosis. The treatment of cervical kyphosis in children varies depending on the severity of the curve. Posterior cervical fusion alone is usually adequate for flexible curves less than 40° to 50° on extension views without evidence of cord compression or neurologic deficits. However, in the setting of curves greater than 40° to 50° on extension views or in the presence of cord compression/neurologic deficits and/or anteroposterior dissociation, a combined anterior/posterior decompression and fusion is recommended.

Disclosures: Okroj reports no relevant financial disclosures. Pahys reports he is a consultant for DePuy Synthes, NuVasive and Zimmer Biomet.

A 5-year-old boy from Cypress presented with a few months of progressive upper and lower extremity paresthesias, weakness and ataxia. His mother contributed to the pertinent history. She denied any significant trauma but said her son had been falling a lot recently. The boy described numbness and tingling in his hands and feet. He also had a lot more trouble playing with his toys and seemed to drop objects frequently. The patient’s mother denied any episodes of bowel or bladder incontinence.

The child’s mother reported a past medical history that was significant for a genetic syndrome characterized by bilateral dislocated knees and clubfeet. The patient required multiple knee and foot procedures as an infant. Since then, however, he had been ambulating unassisted. He did not have any additional medical comorbidities and took no medications. The patient had no known drug allergies.

On exam, the patient had a shortened stature for his age, prominent forehead, flattened nasal bridge and wide-set eyes. He had significant clubfoot deformities bilaterally. He had full strength in his bilateral upper and lower extremities. He had hyperreflexia in his bilateral upper and lower extremities with a few intermittent beats of clonus. He had a positive Hoffman’s sign bilaterally and had an ataxic gait.

Plain radiographs of the cervical spine were obtained. They demonstrated severe cervical kyphosis. CT of the cervical spine obtained to further evaluate the deformity revealed a cervical kyphosis angle of 75° across C4-C6 with a hypoplastic C5 vertebral body, as well as anteroposterior (AP) dissociation of C2-T1 due to pars defects at those levels. MRI of the cervical spine without IV contrast was obtained, which revealed significant spinal cord compression with myelomalacia at C5 (Figure 1). A 3-D CT reconstruction was done of the patient’s deformity (Figure 2).

cervical CT and MRI images
Figure 1. Representative cervical CT (a) and MRI (b) images in the sagittal plane demonstrate the extent of cervical kyphosis and associated spinal cord compression with myelomalacia, respectively.
Figure 2. Representative 3-D reconstruction of a cervical CT scan further demonstrates the patient’s severe kyphotic deformity.

Source: Joshua M. Pahys, MD

What is your diagnosis?

See answer on next page.

PAGE BREAK

Progressive myelopathy due to severe cervical kyphosis in a patient with Larsen syndrome

Due to the progressive myelopathy (ataxia, hyperreflexia) and imaging to confirm the diagnosis, staged AP surgery was recommended to correct the patient’s deformity, stabilize the cervical spine and prevent further progression of his myelopathy. Given that his myelopathy was present for a few months prior to his evaluation, the likelihood of complete resolution of his symptoms was encouraging, but not guaranteed. The parents provided appropriate consent for the procedure. The patient was admitted to the hospital 2 weeks prior to his scheduled procedures and was placed in halo gravity traction to reduce the cervical kyphosis.

The patient then underwent the anterior portion of the staged procedures. Given that the patient had evidence of anteroposterior dissociation of C2-T1 on preoperative imaging, the plan was to extend the fusion through those segments after correcting his alignment. Using a standard Smith-Robinson approach, the anterior cervical spine was exposed and discectomies were performed from C2-T1 in standard fashion. There was significant anterior scar/fibrotic tissue anterior to C5 that was about 1-cm deep, which was dissected through in a layered fashion. Fluoroscopy was used throughout the dissection to confirm the depth. Due to the significant kyphosis from C4-C6, it was elected to perform C5 and C6 corpectomies. Two Caspar pins were placed, one each into C4 and C7, to manipulate the cervical spine into more neutral or lordotic alignment. Despite the gentle traction, the Caspar pins were unable to reasonably realign C4 out of kyphotic angulation and it was decided to remove the body of C4, as well. After performing a corpectomy of C4, Caspar pins were placed into C3 and C7, and gentle distraction was performed to attain proper cervical alignment and reduce the patient’s severe kyphosis back to a neutral alignment. A 9-mm x 40-mm fibular strut graft was carefully malleted into place between C3 and C7. The portions of autograft bone that had been removed from the corpectomy were then gently tamped into place in the C2-C3 interspace. An allograft plug was then gently malleted into the C7-T1 interspace. The properly-sized plate was then assessed using calipers. Given the small size of the patient’s vertebral bodies, no plates were available in a size to allow placement of screws into both C7 and T1. Thus, it was elected to place screws into C3 and T1. The plate was not extended up to C2 due to concern for implant prominence at this level and possible associated morbidity (Figure 3). Postoperatively, the patient was placed in a halo vest to provide additional provisional stabilization prior to his staged posterior fusion.

Postoperative plain cervical radiographs
Figure 3. Postoperative AP (a) and lateral (b) plain cervical radiographs show corrected cervical alignment to neutral.

One week later, the patient underwent completion of his staged procedure. A standard posterior, cervical, longitudinal midline incision was made overlying the spinous processes of C2-T2. Subperiosteal dissection of the posterior elements was carried out to the lateral aspects of the lateral masses from C2-T2. There was significant mobility of the posterior elements from C2-T1 secondary to the patient’s pars defects. The pars defects made it unsafe to place pedicle screws at C2, so a Gill laminectomy was performed bilaterally at C2. A significant amount of scar tissue was removed from the site of the pars defects. Bilateral C2 pedicle screws were placed with the guidance of C-arm fluoroscopy as well as anatomic landmarks. Four lateral mass screws were placed bilaterally at C3 and C5. Levels C6 and C7 did not appear able to accommodate a screw and thus were left empty. Level T1 was then evaluated. A small laminotomy was performed which revealed a pedicle less than 2 mm in size, which was not amenable to safe cannulation. Thus, this level was left empty, as well. Bilateral T2 pedicle screws were then placed with guidance from C-arm fluoroscopy and the anatomic landmarks. Two rods were measured and secured in placed bilaterally. Proper alignment was checked and confirmed using biplanar fluoroscopy. The posterior elements were thoroughly decorticated using a high-speed bur. A mix of 10 mL of autograft, 15 mL of crushed cancellous allograft and 10 mL demineralized bone matrix was made and packed in the decorticated portion of the wound.

PAGE BREAK

Crosslinks were measured and placed at T1 on the rod and a head-to-head crosslink was placed across C2. After closure, the patient was placed back in a halo vest, which he was to wear for 6 weeks postoperatively.

Discussion

The patient presented herein developed severe cervical kyphosis leading to progressive myelopathy due to his underlying Larsen syndrome, which is a rare genetic disorder that results from a genetic mutation in the FLNB gene. It is produces filamin B, a crucial protein that makes up part of the cytoskeleton of cells and has a prominent role in the development of the skeleton in utero. Therefore, patients with Larsen syndrome can be born with clubfeet, dislocations of the hips, knees or elbows, and hypermobility of multiple joints. Spinal instability and cervical kyphosis are additional potential concerns for these patients.

Fewer than 15 cases of severe progressive cervical kyphosis in patients with Larsen syndrome have been reported. All children with this disorder should receive regular screening cervical radiographs at their initial visit. If cervical kyphosis is noted on plain radiographs, CT and MRI are recommended as many of these patients also have complete AP dissociation of the cervical spine.

Surgical intervention is generally recommended prior to the development of severe kyphosis. The treatment of cervical kyphosis in children varies depending on the severity of the curve. Posterior cervical fusion alone is usually adequate for flexible curves less than 40° to 50° on extension views without evidence of cord compression or neurologic deficits. However, in the setting of curves greater than 40° to 50° on extension views or in the presence of cord compression/neurologic deficits and/or anteroposterior dissociation, a combined anterior/posterior decompression and fusion is recommended.

Disclosures: Okroj reports no relevant financial disclosures. Pahys reports he is a consultant for DePuy Synthes, NuVasive and Zimmer Biomet.