Where, as above, C is annuity payment, PV is principal, n is number of payments, starting at end of first period, and i is interest rate per period. Equivalently C is the periodic loan repayment for a loan of PV extending over n periods at interest rate, i.
Refractory epilepsy is a seizure disorder that resists drug treatment. There is some debate among clinicians and researchers about how to define refractory epilepsy. As a result, this term is used in a variety of ways, and when a patient's epilepsy is described as refractory, resistant, or nonresponsive, it can be advisable to ask for more detail about what the diagnosis means.
What Is a Spinal Tap? One test for epilepsy is a spinal tap (also called a lumbar puncture). This is a procedure in which fluid surrounding the spinal cord (called the cerebrospinal fluid or CSF) is withdrawn through a needle and examined in a lab. Why Is a Spinal Tap Performed? A spinal tap may be performed to rule out infections such as meningitis or encephalitis as the cause of epileptic seizures. Besides being used for epilepsy, testing the CSF can help in the diagnosis of disorders of the chronic inflammatory demyelinating polyneuropathy, central nervous system that may involve the brain, spinal cord, or their coverings (the meninges).