Elderly Woman with Leg Weakness

[JNUS]

CLINICAL BACKGROUND

An 87-year-old woman presents to the emergency department (ED) with acute onset of inability to move both of her legs over the past day. She had been hospitalized and discharged 2 weeks ago for a pulmonary embolism and at the time of discharge was feeling well and mobilizing independently. The patient reports mild progressive weakness of her lower limbs over the past 6 months with accompanying back pain. She states that she was able to walk and do her normal activities during that time without difficulty. She has a history of osteoporosis and had a radical nephrectomy for renal cell carcinoma 7 years ago.

On physical examination, the patient appears well, though slightly cachectic. She has a pulse of 90 bpm, a blood pressure of 130/90 mm Hg, and a temperature of 97.7°F (36.5°C). The cardiac and pulmonary examinations are unremarkable, with a regular rhythm and no increased work of breathing. She has a soft abdomen with no rebound or tenderness to palpation. There is evidence of a well-healed scar from her previous nephrectomy. On a scale from 1 to 5, with 5 being full strength, she describes her strength as a 0 in the right leg and a 2 in the left leg. Pain and temperature sensation is absent throughout the lower limbs. There is slightly decreased rectal tone. The remainder of her physical examination is unremarkable.

A magnetic resonance imaging (MRI) scan of the thoraco-lumbar spine is performed (see Images 1 and 2).

What is the diagnosis?

HINT
The recurrence of a prior medical condition is likely responsible

[JNUS]

Answer
Spinal cord compression caused by a solitary metastasis to the T10 vertebral body, with an associated pathologic compression fracture: The sagittal fast spin-echo T2-weighted MRI scan of the thoracolumbar spine demonstrates diffuse replacement of the normal bone marrow of the T10 vertebral body, with associated near-complete collapse of the T10 vertebral segment (see Image 1). The axial T1-weighted MRI scan at the level of the T10 vertebra demonstrates an anterior epidural mass causing critical central canal stenosis; an abnormal signal is also noted within the right T10 pedicle (see Image 2). Diffuse marrow replacement, posterior convexity of the collapsed vertebral segment, and pedicle involvement are all highly suggestive of a pathologic compression fracture.

[JNUS]

Renal cell carcinoma (RCC) is known to produce solitary metastatic deposits even after radical nephrectomy. Although the findings are based on relatively few cases, one retrospective study reported a mean duration of 3.9 years for the formation of a solitary metastatic deposit after a radical nephrectomy for renal cell carcinoma.1 Currently, the preferred therapy for metastatic deposits is radical surgery. Radical radiotherapy is of unclear efficacy, showing a potential benefit in a few studies.2 Other modes of therapy, including immunotherapy with interleukins and interferons, have been utilized with inconsistent results. Up to one third of patients with RCC have metastases at the time of presentation. Of the remaining patients who do not present with metastases, approximately 50% will have metastatic disease after a radical nephrectomy.3 Research of new agents and treatments to identify improved anti-tumor activity against metastases remains a high priority in this refractory disease.

The phenomenon of solitary metastasis in RCC has been the subject of several studies and case reports. The frequency of solitary metastases is less than 5%.13 Patients who develop a single metastasis after removal of the primary tumor appear to have a better chance of recovery and long-term survival than patients who present with a metastasis along with the primary tumor.3,5 Interestingly, one article from Japan reported a case of spontaneous regression of sternal metastases that had developed after a radical nephrectomy. 5

Epidural spinal cord compression as a result of metastatic cancer is a commonly seen complication of certain types of cancers (most typically, lymphoma, lung cancer, breast cancer, and prostate cancer). Other causes of epidural spinal cord compression include certain other types of cancers, such as melanoma and renal cell cancer (as in this case), and other nonmalignant etiologies, such as vertebral subluxation and spinal epidural hematoma. The metastatic lesions usually extend into the spinal canal to compress the spinal cord after initial metastasis to the vertebral body. The majority of cases occur in the thoracic spine (68%), with the remainder being in the cervical spine (15%) and in the lumbar spine (19%). In most patients, insidious back pain over a period of weeks to months is the typical presentation, as in this case. Other common presenting symptoms and signs include weakness, hyporeflexia or hyperreflexia, and sensory abnormalities.8

In cases of suspected spine metastases for back pain in high-risk groups (eg, the elderly, as well as patients with a prolonged duration of pain, a history of cancer, or a non-traumatic etiology), plain film radiographs are reported to be up to 90% sensitive for detecting tumor in the vertebral bodies, but CT is more sensitive and may be required for cases with unexplainable symptoms. Additionally, when the diagnosis is made by screening plain radiographs, CT scanning may be performed to better define the lesion. When spinal cord compression is suspected, MRI is the diagnostic modality of choice for evaluation.

In cases of confirmed spinal cord compression, immediate treatment is necessary. High-dose steroids should be begun to reduce inflammation and edema. Consultation for radiation therapy should be sought without delay, taking into account factors such as the location of the compression, the radiosensitivity of the tumor (if known), and the rate of decompensation. Surgical therapy is indicated in cases of diagnostic uncertainty, spine instability, and post-radiation.

The patient in this case was first treated with radical radiotherapy. After 1 month of radiotherapy there was no clinical improvement in the patient’s condition. Considering the patient’s age and other comorbidities, and as per the patient’s own feelings, the decision was made to forego surgery. The patient is currently in a nursing home, and no further cycles of radiotherapy are being considered at this time.