Functional Changes Following Percutaneous Venoplasty in Multiple Sclerosis Patients

Multiple Sclerosis (MS) is a demyelinating disease of the central nervous system (CNS) that often results in reduced muscle function which produces fatigue, weakness and a decline in daily mobility. Although the underlying cause of the disease is unknown a possible contributory mechanism is chronic cerebrospinal venous insufficiency (CCSVI). Post-mortem studies and magnetic resonance venography have shown a strong relationship between the cerebral venous system and MS cortical plaques. From this a role for CCSVI in MS has been suggested: venous malformations that result in venous hypertension, pressure on the blood brain barrier and subsequent inflammation due to leakage of haemosiderin into the parenchyma. This provokes an immune response which results in neurodegeneration. A procedure known as percutaneous venoplasty whereupon a balloon is inserted and inflated into the jugular vein has been developed to improve this drainage of the CNS, reduce venous hypertension and improve symptoms associated with MS. Although this procedure is widely practiced throughout the world it has yet to be fully accepted as it needs to be supported by evidence based clinical trials. As such NHS National Institute for Health and Clinical Excellence (NICE) recently issued a consultation document to determine more about the procedure's clinical safety and efficacy. A common concern raised is the ability to prevent any possible placebo effect and like any other clinical trial should offer a sham procedure to a matched control group. The difficulty with this option are the ethical issues associated with an invasive sham treatment and also the practical issues of masking a potentially painful treatment such as venoplasty. One option is to have blinded neurological assessment of patients who have either been treated with venoplasty or had no active treatment. Another option is to use dependent measures that are unaffected by motivational or psychological influences which avoids any placebo effect issue. One such dependent measure is motor unit firing behaviour whilst contracting at a submaximal target force. Typically clinicians have used this to manage motor disorder patients but have used cumbersome invasive technology that can only measure a few motor units with limited accuracy. However, De Luca et al recently developed a high density surface electromyographic (HDsEMG) system that can measure 30-40 motor units with 92-97% accuracy. From this it has been proposed as a highly effective tool for evaluating efficacy of therapeutic interventions for upper motoneuron disorders such as MS.

Accordingly the investigators propose to use a repeated measures design on an experimental (receiving venoplasty) and control (not receiving venoplasty) MS groups (6 patients in each group) to determine the effect of the treatment on muscular function, mobility and fatigue. This would be combined with independent blinded neurological assessment of the two groups of patients.

This design enables us to achieve two aims:

1. Acute neuromuscular response to the treatment
2. Chronic response to the treatment (6 weeks) to determine the effect on muscular function, mobility and fatigue.*

Methods

• Four (first two to establish baseline variability of measures) repeat visits to the laboratory at University of Stirling to establish neuromuscular measures:

  1. HDsEMG pre and post tetanic induced fatigue
  2. Muscle fibre conduction velocity as previously described (Hunter et al., 2011)
  3. Ultrasound for CCSVI determination on visits 1 and 3
  4. DEXA scans for alterations in body composition on visits 2 and 4
• With the use of accelerometers monitor free living activity on days 0-7 and 9-42 (post venoplasty).