Follow-up/Toxicity

Question 1

What is the Lhermitte sign? When does it occur, and what causes it?

Answer 1

The Lhermitte sign is shocklike sensations in the extremities on neck flexion. It occurs within 2–6 mos of RT from demyelination of the nerve tracts.

Question 2

When does RT myelopathy occur, and what is the temporal sequence of onset for neurologic deficits?

Answer 2

RT myelopathy occurs 13–29 mos after RT, with paresthesia → weakness → pain/temperature loss → loss of bowel/bladder function.

Question 3

Per QUANTEC, what is the risk of myelopathy with 1.8–2.0 Gy/fx to the full thickness of the cord at 54 Gy? At 61 Gy?

Answer 3

<1% at 54 Gy, <10% at 61 Gy (Kirkpatrick JP et al., IJROBP 2010)

Question 4

Per QUANTEC, what is the risk of myelopathy with SRS to the cord to 13 Gy in 1 fx? To 20 Gy in 3 fx?

Answer 4

<1% with 13 Gy/1 fx, <1% with 20 Gy/3 fx (Kirkpatrick et al., IJROBP 2010)

Question 5

Within what timeframe do SC astrocytoma pts usually relapse?

Answer 5

Relapse in SC astrocytoma pts usually occurs within 2 yrs (most in-field).

Question 6

How long of a f/u is required after SC ependymoma resection?

Answer 6

> 10 yrs f/u is required, as late recurrences (>12 yrs) have been reported in 5%–10% of pts.

Question 7

What region of the SC has traditionally been thought to be most sensitive to RT? Least sensitive?

Answer 7

The lumbar SC is thought to be most sensitive to RT, while the cervical cord is thought to be least sensitive.