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As most of us know, the impact of any problems associated with CMT can be highly variable, even within families. Some people show no, or only a few signs, while some will have more significant disability. When people receive a new diagnosis of CMT for themselves or their children, most seek information about the various secondary features and the possible future impact. To-date the available information has been patchy. The results of this survey fill in many of the gaps, provide us with a better idea of the likely complications, and indicate how successful some of the commonly used treatments are considered to be by people with CMT.
The aims of the study were:
The survey consisted of three parts, two existing survey forms and a tailored set of questions, specific to CMT. The inclusion of existing surveys allowed for comparison with other disorders where the impacts of an illness had been evaluated. After piloting of the CMT specific questions, the surveys were sent to all members of the CMTAA mailing list. The survey was posted at the end of 2001 and the data collated in the first quarter of 2002.
The final response rate was 324 completed surveys, received from 520 mail-outs (63%). The sample consisted of 132 males (40.7%) and 192 females (59.3%).
Eighty-five (26%) had never married, 198 (61.1%) were currently married or living in a de facto relationship, 27 (8.3%) were separated, divorced or currently single, and 14 (4.3%) reported their marital status as widowed.
The mean reported age of the sample (N=320) was 46.2 years (46.2 years for males and 46.7 for females), with a range of 2 to 87 years. There were 18 (5.6%) respondents aged less than 16 years, and 61 (16.9%) aged 65 years or older.
The average age at onset of symptoms was 21.2 years and the average age at diagnosis was 31.9 years. More than one-quarter of people reported having had a misleading initial diagnosis. A quarter of these were initially told there was nothing wrong, while a third of those with an initial misdiagnosis were told they had polio or cerebral palsy. Another 18 different misdiagnoses were also reported.
General health was evaluated using an existing instrument called the SF-36. The SF-36 can evaluate the impact of a disorder such as CMT on eight aspects of a person's life. The eight aspects (or dimensions) are:
The SF-36 scores in each dimension range from 0 to 100, with 100 theoretically perfect and 0 as bad as possible, (higher scores = better health).
As the graph shows, people with CMT score lower than the general population, particularly in the physical dimensions. The physical function dimension is the worst affected, while the mental health scores remain high.
The SF-36 scores for males and females were very similar, but increasing age worsened the SF-36 scores slightly more than in the general population (not shown here). This seems to suggest that the effects of age combined with CMT will slightly accelerate reduction in physical function throughout the lifespan.
In comparison with a range of other conditions, CMT appears to lie in the mid range for impact on the eight dimensions. People with CMT are report less impairment than people with painful arthritis, and the CMT group report broadly similar scores to people with other chronic conditions such as Parkinson's disease or stroke after three months of convalescence. Data such as these should help doctors better gauge the impact of CMT relative to other more common conditions. CMT does affect peoples' lives and we now have context for the amount of effect.
The foot specific health measures from the Foot Health Status Questionnaire (FHSQ) were also interesting. As might be expected, the scores for people with CMT were consistently lower than for the general population. Within the CMT group there was also a big difference between male and female scores in relation to footwear, with women reporting more difficulty with foot wear than men. The amount of foot pain experienced by people with CMT was not as bad in comparison to the general population as were the other three domains, while foot function scores were much lower than normal.
It is not possible to detail all of the findings from such a large survey in the limited space available here, so an overview of the most important points will be provided. Muscle weakness was very common (more than 80% of people), and was more profound in the lower limbs than the upper limbs. Severity of muscle weakness was associated with many of the features of CMT, and proved to be a very useful predictor of quality of life.
Scoliosis was reported to be more common than in the general population, although none of the other factors explored in this study predicted the severity of scoliosis. The link between scoliosis and CMT remains unclear, but fortunately, only a small proportion of people with CMT suffer with significant scoliosis.
The prevalence of tremor was higher (47%) than has been reported previously in studies employing doctor-based assessment of tremor severity. This raises the question of whether patients are hypersensitive to 'normal' tremor, or whether clinicians, without including patients' perceptions, tend to trivialise minor tremor.
Sensitivity to cold is often mentioned by patients with CMT, and increased sensitivity to cold in the legs and feet was a reported by three-quarters of respondents. Any sensitivity to cold was perceived to be worse in the legs than the feet.
Flat feet were reported to be a relatively uncommon presentation in CMT, with fewer than 15% of respondents reporting significant flat footedness. Indeed, more than 80% reported their feet as not being flattened 'at all' - a figure in-line with previous studies. There was less flatfoot in the younger age groups.
High Arches
The high prevalence of a cavus (high arched) foot type was in agreement with the previous literature, and CMT1A specifically, was associated with the most high arched feet.
Impairment to hearing and vision appeared to be reported more frequently in the CMT group than in the general population, although this study made no distinction between changes associated specifically with CMT, and other causes of hearing and visual impairment. Age was the factor the most closely linked to vision and hearing deterioration. Nonetheless, the prevalence was apparently increased in the CMT respondents over the general population, and was also related to muscle weakness. This suggests some link with the physiological processes occurring in CMT.
Similarly, leg weakness also appeared to be correlated with bladder, bowel and sexual dysfunction in people with CMT. This does appear to be an area of concern to the CMT community, and further study of this area by experts in the field is warranted.
Sensitivity to cold
Sensitivity to cold is often mentioned by patients with CMT, and increased sensitivity to cold in the legs and feet was a reported by three-quarters of respondents. Sensitivity to cold was perceived to be worse in the lower limbs than the upper limbs.
Slowed reaction to pain was also noted, along with increased susceptibility to burns. Leg and foot weakness was again strongly related to the sensory effects reported in this section of the survey.
In addition to the impairment of sensation in CMT, the survey also explored the positive sensory problems. Shooting pains in the limbs]were troublesome for more than half of the respondents in this sample.
The prevalence of 'pins and needles' is higher again, affecting more than three-quarters of the people with CMT. For both of these presentations the lower limb is affected more than the upper limb.
The other positive physical signs explored in the survey are cramps and restless legs. This survey also confirmed a high prevalence of leg cramps in people with CMT (more than ¾ of people) and the relationship between weakness and prevalence of cramps was again strong. Severity of leg cramps was also a highly significant factor in the models predicting quality of life, and it seems as though the importance of cramps may have been underestimated previously.
Three-quarters of the sample also reported restless legs, a higher proportion than reported in studies employing physician definition/diagnosis of the problem. Again there was a relationship between restlessness of the legs and weakness.
The next stage for us is to finalise the full report, which will go to a number of organisations including the CMTAA. The main report is highly technical and runs to more than 150 pages, but the sections will be chopped up into more manageable chunks and published in the medical journals over the next 12-18 months. I am sure the CMTAA will keep the membership up to date as the papers come out.
Balance
One real-world manifestation of impaired sensory function sometimes reported by patients with CMT is altered balance.
In this sample, differences in balance capacity during static standing and in walking on flat and uneven surfaces were confirmed by more than three-quarters of respondents.
Balance was strongly correlated with the severity of leg/foot weakness. People with CMT appear to have particular problems with static standing. The problem is lessened to some degree when walking on the flat, but walking on uneven surfaces however, causes significant balance problems. Knee bending is a common strategy for improving balance, and nearly two-thirds of the CMT sample reported adopting this compensation mechanism.
Of great concern is the number of falls to the ground reported by people with CMT. The risk of falling did not appear to be closely linked to age as is seen in the general population, but was strongly associated with leg/foot weakness, implying a CMT specific mechanism. For one-quarter of all our respondents, falls to the ground are reported as occurring 'often' or more frequently. This should cause great concern to doctors.
Aids and other devices likely to be required by people with worst impairment, (wheelchairs, electric scooters, walking frames etc) were not used by many respondents. The proportion of our sample using a wheelchair to aid mobility (6%) was actually slightly less than suggested in the anecdotal literature. Singles were more dependent on a wheelchair for mobility than were people with a partner. Dependence on these 'high-end' aids was related both to age and severity of weakness. Walking stick and walking frame use was again highly age dependent, although leg/foot weakness was also implicated. This suggests that disease related weakness might add slightly to the increase in dependence on common walking aids normally associated with ageing. Kitchen and dressing aids were not widely used and are only considered helpful by those with more significant upper limb weakness.
Over one third of respondents reported using in-shoe orthoses, and 70% reported them to 'quite helpful' or better. In-shoe orthoses are better suited to people with less weakness. Ankle-foot orthoses (AFOs) were used by fewer people than reported using in-shoe orthoses, and were generally used by those with worst leg/foot weakness. AFO's were very unpopular in the age group 21-40 years, and their use in this group was only one-fifth of that in the other age groups. Conversely in the 61-80 age group, the prevalence of AFO use was double that expected.
The FHSQ results suggested that the 21-40 age group also find footwear issues particularly profound and it is possible that the same factors may be implicated, namely a trade-off between social acceptability and the appearance, against the burden of disability imposed by the CMT. The many factors likely to influence success with this treatment should be considered carefully by the doctor/orthotist/podiatrist etc when AFOs are being contemplated, and patients need to be honest with their feelings about wearing such devices.
Of the more aggressive non-surgical therapies, night splinting was generally considered unhelpful and raised difficulties with compliance. Again, the best results were reported by patients with less weakness, but overall, night-splinting did not appear to be a popular treatment. Unsurprisingly, plaster casting was considered more difficult to comply with than removable night splints, but conversely, casting was also considered marginally more effective.
Strengthening of weakened muscles, either weight bearing or non-weight bearing, was considered effective by the majority. Again this approach appears to be suited better to people with milder weakness. There is little to separate weight bearing and non-weight bearing regimens, although the weight bearing approach was considered marginally more effective, perhaps reflecting its improved relevance to real-life activities.
Stretching is widely advocated, and had been tried by 70% of the respondents. Stretching exercises are considered easy to use, and are considered effective by half the respondents. Again stretches were more likely to be reported as effective by People with milder weakness.
Alternative therapies were widely used, with a variety of approaches reported. Many respondents who had tried one alternative approach also tried other alternative therapies. Massage and chiropractic were the two alternative treatments felt to be most effective by respondents in this sample. Acupuncture was the only other alternative therapy tried by enough respondents to warrant detailed exploration, but was not considered effective by most who had tried it. Alternative therapeutic approaches to managing the symptoms associated with CMT evaluated much more poorly than expected, and must therefore be viewed with some caution. The more conservative approaches (massage, chiropractic) may be of limited use to some people, but the alternative therapies proved disappointing overall.
Surgery
Surgery for CMT is an area of great concern as there are no gold-standard treatments. People with least weakening had the best chance of avoiding surgery, while those with the most weakness tend to undergo arthrodesis.
The younger patients in this sample tended to have more tendon transfers as first surgery although there was considerable overlap between the approaches. Somewhat surprisingly, all the surgical approaches were considered similarly traumatic by the respondents, with joint fusion considered marginally more effective, but tendon transfers marginally more worthwhile.
None of the differences were statistically significant. Osteotomies were usually reported as repair procedures, or as forefoot surgeries for toe deformity, and were performed on more females than males.
Given the apparent absence of factors in this survey able to predict allocation to these surgical groups, then perhaps the differences are less significant than we currently think.
The final part of the analysis was to use a statistical technique to investigate which of the factors in the survey might be used to predict the overall quality of health. Of the general physical health dimensions, leg/foot weakness was the single most influential factor in the analysis, and was linked to the scores in each of the four SF-36 physical dimensions (More weakness = worse health scores). Age was also linked to reduced physical quality of life scores, as it is in the general population. The amount of pain experienced appeared to be affected more by the presence of cramps than physical factors such as foot deformity, although people who had undergone more invasive surgeries such as arthrodesis and osteotomy also reported worse pain scores. We do not know whether this reflects the outcomes of the surgeries themselves though, or the choice of more severely affected patients for these procedures.
Foot pain was highly influenced by presence of cramps and by leg/foot weakness, and foot pain was also worse in older people. Foot function was strongly related to leg/foot weakness and age, while a history of more invasive surgeries and the frequency of cramps turned out to be fairly minor factors. This suggests a compounding effect of CMT related disability over the lifespan. Problems with footwear were overwhelmingly influenced by gender.
Foot pathology
It is likely that the mismatch between the female foot and shoe recognised in the general population, is even worse in people with a foot pathology related to CMT. Women with CMT may have particular trouble finding and buying suitable footwear from high street outlets. The CMTAA have collated a list of shops that had been useful to CMTers and may be of help to you.
Finally, the importance of leg/foot weakness in predicting the impact of CMT disease on the lower limb is illustrated well in the FHSQ measure of 'general foot health', which turned out to be highly dependent on the severity of leg/foot weakness.
In summary, this survey has given us a valuable insight into the effects of CMT, and for the first time, enough information to be able to draw some conclusions about the links between the symptoms and the clinical signs. The amount of weakness appears to tell us much about the type and severity of problems likely to be encountered. Estimation of weakness tell us a lot, even without detailed clinical measurements, because the patients' own perspectives seem highly relevant. Very few people in this survey reported needing to use mobility aids, and the incidence of wheelchair use was lower than often quoted, and related as much to age and marital status as CMT. Conversely the more 'minor' symptoms (such as tremor, pins and needles etc) might have been under-reported in medical studies, and could be more common than previously thought. Cramps make a more significant impact on the quality of life measures than had been recognised before and are probably over-trivialised currently. Poor balance is an issue in the CMT community, as we know, and the consequent problem with increased risk of falling should perhaps be given more consideration also. Conservative treatments are most effective for people with mild weakness, and alternative therapies did not appear as effective as might have been expected. Surgical treatment remains as mysterious as ever.
The next stage for us is to finalise the full report, which will go to a number of organisations including the CMTAA. The main report is highly technical and runs to more than 150 pages, but the sections will be chopped up into more manageable chunks and published in the medical journals over the next 12-18 months. I am sure the CMTAA will keep the membership up to date as the papers come out.
Finally I would like to thank everyone who participated in the survey process. Our thanks are due, not least, to the 324 who returned their forms, to the many hundreds who donated to the 'fighting fund', to the CMTAA committee, to the survey proof readers, and others too many to be named individually.
In particular though, we all owe a debt of gratitude to the wonderful June Shepherd. As well as producing the newsletter, June spends many hours on CMTAA business, and June was instrumental in running this survey. She mailed out the forms, followed up requests, collated responses, manned the phones and entered the data. Without June this survey simply would not have happened.
Thank you.
Our Thanks to Tony for the inspiration to do the survey and for all his work on compiling the statistics. You can see by the results that there have been some surprising results that are going to enlighten our Health Professionals.
The National Committee would like to thank all who took the time and effort to complete the forms and return them.
We hope the results were worth the effort.
June Shepherd.