94 Intramedullary Spinal Tumor

Amgad S. Hanna and William E. Krauss

Fig. 94.1 (A) Sagittal magnetic resonance imaging of the C-spine with T2-weighted image and (B) T1-weighted image with gadolinium revealing an intramedullary tumor. On T2-weighted images, the tumor is isointense to the spinal cord, with hypointensity (hemosiderin deposits) above and below the tumor and a hyperintense overlying syrinx. There is heterogeneous enhancement after gadolinium.

Clinical Presentation

A 47-year-old woman presents with a 4-year history of intermittent tingling of the left hand that has progressively gotten worse and is now also involving the left lower extremity.
There was no loss of bowel or bladder function and no headaches.
The medical history is remarkable for mitral valve prolapse and two breast biopsies for benign lesions.
Neurologic examination was completely normal.

Questions

What is the differential diagnosis?

What studies do you need to order?

The study you ordered is in Fig. 94.1. Describe the findings and the current differential diagnosis.
What treatment would you recommend to the patient? What are the risks?
What equipment do you need? Describe the surgical procedure. Figure 94.2 is an intraoperative view; how would you proceed?
The pathology is shown in Fig. 94.3. What is your diagnosis?
Figure 94.4 is the postoperative magnetic resonance image (MRI); what is her prognosis? What treatment do you recommend at this point?
Eight months later, she complains of sagging of her head and weakness and spasticity of the left leg. The radiograph is shown in Fig. 94.5. What would you do?

Fig. 94.2 Magnified operative view using the microscope. Note the swollen cord and grayish discoloration.

Fig. 94.3 Histological section revealing perivascular pseudorosettes, characteristic of ependymoma.

Fig. 94.4 Postoperative T2-weighted magnetic resonance imaging reveals no tumor mass.

Fig. 94.5 Lateral C-spine radiograph demonstrating postlaminectomy kyphosis.

Answers

What is the differential diagnosis?

Anatomic

The sensory symptoms involving the left upper and lower extremities localize the lesion to the cervical spine, brainstem, or right parietal lobe.

The absence of headache and facial symptoms makes it less likely to be the parietal lobe.

The absence of cranial nerve involvement makes it less likely to be the brainstem.

This is probably a cervical spine lesion.

Etiological 1

Degenerative: disk herniation, synovial cyst, cervical stenosis usually associated with pain and/or myelopathy

Neoplastic: extradural (metastasis, primary bone tumor), intradural extramedullary (meningioma, schwannoma, neurofibroma, ganglioneuroma), or intramedullary (ependymoma, astrocytoma, hemangioblastoma). The chronic progressive symptoms fit with a benign neoplastic etiology.

Vascular: cavernoma. Arteriovenous malformations (AVMs) usually present acutely or subacutely. Spinal cord infarcts present acutely, usually with motor symptoms.

Demyelinating: multiple sclerosis (MS). The remittent course fits with an MS plaque, although the age of onset in MS is usually younger. Transverse myelopathy presents acutely or subacutely with more dramatic deficits.

Others: trauma, radiation myelopathy, epidural abscess, and acquired immunodeficiency syndrome (AIDS) are less likely from the history. Toxic/metabolic — alcoholism, vitamin B12 deficiency. Syringomyelia usually presents with bilateral loss of pain and temperature sensation in the upper extremities and spastic paraparesis. Enterogenous cysts, dural ectasia, and arachnoid cysts are rare.
What studies do you need to order?
- Cervical spine MRI with gadolinium.
- Laboratory work: vitamin B12 level; methyl malonic acid and homocysteine levels; serum and urine protein electrophoresis; complete blood count; electrolytes
The study you ordered is in Fig. 94.1. Describe the findings and the current differential diagnosis.
- Sagittal MRI of the cervical (C-) spine reveals an intramedullary tumor.
- On T2-weighted images, the tumor is isointense to the spinal cord, with hypointensity (hemosiderin deposits) above and below the tumor, and a hyperintense overlying syrinx.
- There is heterogeneous enhancement after gadolinium.
- The commonest intramedullary tumor in this age group is ependymoma followed by astrocytoma. Others include hemangioblastoma, schwannoma, and metastasis.
- The hypointensities on T2-weighted images above and below the tumor are characteristic (though not pathognomonic) of ependymoma.¹
What treatment would you recommend to the patient? What are the risks?
- We recommend surgical resection of the tumor (given the extent and appearance of the lesion on MRI and the progressive nature of the symptoms).
- Risks include neurologic deficits like paraplegia or quadriplegia, loss of bowel or bladder function, respiratory failure, tracheostomy, and ventilator dependency, cerebrospinal fluid leak, neck pain, cervical instability, tumor recurrence, hematoma, infection, and spinal cord ischemia.²
What equipment do you need? Describe the surgical procedure. Figure 94.2 is an intraoperative view; how would you proceed?
- Equipment needed intraoperatively includes the following:
  - Mayfield (or other kind) head holder
  - Jackson radiolucent table or chest rolls
  - Neurophysiologic monitoring with motor evoked potentials and somatosensory evoked potentials
  - Intraoperative ultrasonography (US) for tumor localization
  - Operative microscope and microinstruments
  - Ultrasonic surgical aspirator³
- Details of the surgery are as follows:
  - After cervical laminectomy, the dura is opened and tacked (Fig. 94.2).
  - A midline myelotomy is performed starting in the area of grayish discoloration.
  - If the tumor is hard to find, intraoperative US could help.
  - A specimen for frozen section should be immediately sent.
  - Tumor debulking is then started using suction or ultrasonic aspiration.
  - If pathology reveals ependymoma, and a good margin is visualized between the tumor and the spinal cord, every effort should be made for gross total resection.
  - In the case of astrocytoma, the margins are usually difficult to define; the goal is to remove as much as can safely be removed.
  - After careful hemostasis, the dura is closed with or without patching.
  - One may argue to fuse the laminectomized levels.
The pathology is shown in Fig. 94.3. What’s your diagnosis?
- Figure 94.3 reveals perivascular pseudorosettes, which are characteristic of ependymoma.⁴
Figure 94.4 is the postoperative MRI; what is her prognosis? What treatment do you recommend at this point?
- Postoperative T2-weighted MRI reveals no residual tumor.
- If this is confirmed by gadolinium-enhanced MRI, the prognosis is very good because complete resection can be curative.
- Clinical as well as radiologic observation should be recommended at this point.
- Radiation therapy should be recommended only in cases of incomplete resection.^5–8
Eight months later, she complains of sagging of her head and weakness and spasticity of the left leg. The radiograph is shown in Fig. 94.5. What would you do?
- Lateral C-spine x-ray reveals a postlaminectomy kyphosis.
- For this reason, one may argue for fusing prophylactically after a laminectomy.⁹
- At this point, the patient may be put in traction to correct the cervical alignment.
- Traction is followed by a posterior fusion (in this case with lateral mass screws and rod fixation) (Fig. 94.6).
- If reduction is not possible, a combined anterior and posterior approach may be required. This can involve a multilevel anterior cervical diskectomy and fusion, followed by posterior release of the facet joints.¹⁰