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Treating Guillain-Barre Residual Fatigue with Dalfampridine

Potassium Leakage from Incompletely Remyelinated Axons

Research Sources

Dalfampridine
Potassium-channel blocker improves walking in Multiple Sclerosis patients
(National MS Society)

Potassium Blood Level
Specimen collection protocol: How to avoid in vitro hemolysis
(Gamma DynaCare Lab Canada)

Guillain-Barre Syndrome can cause profound residual fatigue. I know: I am a survivor. Taking extra potassium improves my muscle strength. Without it, I have weakness that becomes tremors at its worst.

For three years – from 1997 to 2000 – I ate one 200-gram can of salmon a day, literally. By accident, I had discovered that salmon settled a symptom of forceful (but slow) heartbeat which worsened when I lay down and disrupted sleep. This symptom later proved to be a mere side-effect of a new prescription (felodipine, a calcium-channel blocker) which treats pre-syncopal dizziness.

During those years I noticed that my regular salmon meals also improved my muscle stamina. At the time, I assumed the useful ingredient was protein, though it was a conundrum: Why should salmon work so much better than other proteins (beef or chicken) in boosting my muscle stamina?

Canned Salmon: Excellent Source of Potassium

Label: Canned Salmon
Canned Salmon: Nutrition Label after 2000
236 gm potassium per 1/6 can
Click for large view

Before 2000, cans of salmon bore a simple label saying only Ingredients: salmon, water, salt.

From 2000 onward, nutrition labels on food became more detailed. In particular, the tall economy-size can of salmon began to list vitamins and minerals along with the basics. Studying the new label, I noticed a high potassium content (image, left).

According to the label, one-sixth of the can contains 236 grams of potassium. Therefore half the can – the amount I consumed daily – provided 708 grams of potassium.

My physician agreed that potassium could improve forceful heartbeat, but he could not explain why this mineral would improve muscle fatigue from Guillain-Barre Syndrome.

Still, the idea percolated in the back of my mind. For several more months I did the salmon thing (by now such a chore that I bypassed plates, spooning it straight from can to mouth). Finally I tried this experiment: I bought Potassium Gluconate tablets over-the-counter and took that in place of salmon. It worked. Potassium alone restored a degree of muscle strength. What a relief: I like the flavor of salmon, but after three years felt utterly saturated with it.

Measuring the Level of Potassium in Your Bloodstream

Before taking a potassium supplement, seek your doctor's advice on these points:

  • Have your doctor check your blood level of potassium. On a lab report, the value is recorded beside the letter K (the chemical symbol for potassium).
  • Your lab test will guide whether you need the supplement, and the appropriate dose.
  • Ensure the supplement doesn't conflict with other prescription and over-the-counter medicines that you take. It is a good plan to develop a working relationship with your pharmacist, who is the best resource for prescription questions.

My own lab tests verify I need the supplement. Refer to the table below. Note: different labs use different equipment and techniques; it is important to use the units, and the normal or reference range, printed on your own personal lab report.

Gamma-Dynacare Lab Saskatoon, Canada Normal range for Potassium:  3.5 to 5.1 mmol/L
When I take Potassium Gluconate tablets daily My blood potassium varies between 3.6 to 4.2 mmol/L
The result is low-normal (inside normal range, but at very low end)
When I am not taking the supplement My blood potassium quickly goes down to 3.2 mmol/L
The result is below normal

Potassium supplements are useful and necessary for me. The question is why – what process causes me to lose the potassium I have in my body, and why do I need so much replacement? Neurology researcher Dr. Gareth J. Parry may have an answer.

Researchers adapt new MS treatment for GBS

MS Patients with Walking Impairment

In January 2010, the US Food and Drug Administration (FDA) approved dalfampridine to treat walking impairment in patients with Multiple Sclerosis (MS). Dalfampridine, a potassium channel blocker, proved in clinical trials that it improved walking speeds. It is the first prescription approved to treat the ongoing disability. Previously, MS treatments were aimed at reducing the relapse rate of the disease.

Parallel: GBS Patients with Residual Fatigue

The most common form of Guillain-Barre Syndrome is Acute Inflammatory Demyelinating Polyradiculoneuropathy (AIDP). Inflammatory cells and anti-ganglioside antibodies dissolve the myelin sheath (Schwann cells) and sometimes the axon of peripheral nerves. The disease progresses swiftly, reaches a plateau after 2 to 4 weeks, then is followed by a recovery phase where the peripheral nerves regrow at a rate of about one inch per month.

The received wisdom is that Guillain-Barre patients who incompletely recover are those with more severe damage to the axon, since axonal repair is a slower and less effective process than myelin repair.

But that does not explain persistent observations. Research neurologist Dr. Gareth J. Parry says: Some patients exhibit residual slowing of the conduction speed of electrical impulses, the hallmark of incomplete repair of the myelin sheath, even years after the initial event. The degree to which this reduces efficiency of nerve and muscle function is not completely known.

Residual fatigue has a serious impact on the lives of Guillain-Barre survivors. Nearly 80% of patients report disabling fatigue; a smaller percentage report residual weakness or sensory loss. Parry believes these symptoms could be related to incomplete remyelination which reduces the efficiency of electrical impulse transmission.

Block the Potassium Leakage from Damaged Axons

According to Parry: The chemical 4-amino-pyridine (4-AP) improves nerve conduction in the central nervous system (CNS) in experimental studies. It works by blocking the potassium channel in the wall of the axon. In incompletely remyelinated axons the potassium channels are exposed, allowing potassium to leak out of the axon. Even if the core axon is intact, the myelin wrapping the axon is sufficiently changed to impair the nerve's ability to conduct electrical impulses.

The chemical 4-AP partially prevents leakage of potassium and improves nerve conduction. This is the reason why 4-AP, in the form of dalfampridine tablets, improves walking in MS patients. Since MS is characterized by demyelination and incomplete remyelination in the central nervous system, Parry suggests that dalfampridine may also help Guillain-Barre patients with residual fatigue, weakness, or sensory loss due to incomplete remyelination of the peripheral nervous system.

Differences Between CNS Myelin and Schwann Cells

The dalfampridine treatment which helps MS patients may not necessarily apply to Guillain-Barre. MS affects myelinated axons in the central nervous system, while GBS affects myelinated axons in the peripheral nervous system (Schwann cells). The two categories differ in important ways:

  • The CNS remyelinates much less effectively than do peripheral nerves.
  • CNS axons transmit extremely rapid trains of impulses at rates of 100–300 pulses per second. Peripheral nerves transmit at a much slower rate of 40–50 pulses per second.

MS patients benefit from dalfampridine because it addresses the ways that CNS electrical transmission is known to fail. But there is hope for GBS, says Parry: There is a possibility that 4-AP in the form of dalfampridine could meaningfully improve GBS patients who have incompletely recovered, particularly those in whom fatigue is the most disabling symptom. Clinical trials will be necessary to determine the benefit.

Georgena S. Sil
Saskatoon, Canada
Physicist & Technical Writer
Alumnus: University of British Columbia
TuumEstContact@protonmail.com

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