- Type I CRPS is a vague syndrome of inordinate pain with variable – vague neurologic weakness or numbness features (unlike type II in which the nerve has definely been cut). Typical scenario is after a wrist fracture in patients with low vitamin C levels. Limb can become very painful, tender to touch, cold, and weak – more or less useless. Pains can become overwhelming.
I have mentioned previously how IV pamidronate could be useful here and IV Magnesium here
Now it looks like repeated 4 hour magnesium 70 mg/kg infusions repeated over 5 days can have some lasting effects.
Intravenous Magnesium for Complex Regional Pain Syndrome Type 1 (CRPS 1) Patients: A Pilot Study (p )
Susan Collins, Wouter W. A. Zuurmond, Jaap J. de Lange, Bob J. van Hilten, Roberto S. G. M. Perez
Published Online: Jun 1 2009 Pain Medicine in press
- 10 cases – most occurred post fracture or sprain (one spontaneous)
- 70 mg/kg magnesium daily – that would be like 5 gms/day for a 71 kg being….
- This dose was made up to 100 mls with saline and infused at 25 ml/hour – they used a 50 ml infusion pump, used twice each session
- Siince it can aggravate heart block, an ECG was done prior to look for prolong PR interval or any heart blocks and “ECG monitoring was performed continuously during the administration”
- cases avoided included:
- Known kidney
- severe liver disease;
- Active infection
- Malignant disease;
- Heart failure;
- Pacemakers or implanted defibrillators
- Pulmonary congestion
- “One patient dropped out after 3 infusion days due to side effects (dizziness, headache and pain in infusion arm).”
- first day, 1/2 had high magnesium levels – 1.25 +/- 0.23 mmol/liter – they were normal the following days.
- Side Effects included
- pain (N = 5/10),
- flushing (N = 4),
- nausea (N = 2),
- vomiting (N = 1),
- fatigue (N = 4),
- headache (N = 1),
- dry mouth (N = 1),
- burning eyes (N = 4),
- palpitations (N = I),
- dizziness (N = 4),
- lightheadedness(N = 2),
- diarrhea (N = 1).
- the high Magnesium levels day one are disturbing though they say higher levels are used safely in eclampsia of pregnancy
- 1/2 had arm burning – a feature I have noted and patients seemed to find particularly distressing; adding IV lidocaine with it did not help( and would potentiate heart block)
- the benefits took weeks for full effect – which I find suspicious
- Having said that, IV Magnesium is considerably cheaper than pamidonate.
- Some improvement of impairment was noted.