29 April 2007

Lutes and Lumbricals

Lumbrical Muscles
DSM: A lute player friend of mine has been having progressively more difficulty with his left hand. Focal Dystonia, probably. Nothing so bad as Leon Fleisher’s difficulties years ago or anything like that. But still a major impediment to his performance practice and concertizing.

CMT: There’s still the problem of diagnostic accuracy for Focal Dystonia—and the imprecision of knowing how a loss of “representational specificity” or other changes in the brain can come about through over-use of the hand; the uncertainty of explaining why Botox injected peripherally actually brings about an improvement in this condition if the cause is ‘central’, in the brain. Is your friend sure that it’s Focal Dystonia and not Carpal Tunnel Syndrome or something else?

DSM: Well, no. The neurologists he’s seen have been inconclusive. One hand surgeon wanted to persuade him to be operated for Carpal Tunnel, but my friend regards that as a last resort. And the neurologists’ EMG and imaging and other studies have not been terribly helpful in ruling anything in or out yet. His main complaint has to do with a loss of strength in the lumbrical muscles in his hand, especially the ones involved in moving the middle finger and the ring finger. So it’s not a textbook picture of Focal Dystonia. I suspect he’ll have to go to one of the Performing Arts Medicine clinics that have neurologists experienced in this, as opposed to the well-meaning neurologists and electromyographers he’s seen so far, who have no particular expertise in the problems of musicians.

CMT: There are probably some string players with variant anatomy who just happen to have asymmetrically strong mechanical connections between the ring and middle extrinsic flexor muscles.

Supposedly the phenomenon of middle-ring ‘enslaving’ or ‘subordination’ has a big neural component. If it’s ‘central’ or ‘neural’ then in principle it should be susceptible to retraining through exercises. The connections between adjacent digits involving tendons and muscle fiber groupings of the deep flexor (flexor digitorum profundus) play a big part, though. The ‘peripheral’ biomechanical component shouldn’t be underestimated—it definitely contributes to some of the ‘enslaving’ or ‘subordination’ of one finger to the other. But recent work is showing that enslaving effects among different hand muscles involve both central neural interaction among the structures controlling flexor muscles and lumbricals in the hand as well as peripheral mechanical interactions.

It’s possible that your friend is someone who just happens to have anatomy with substantial tendon sharing. In medical school, I dissected a hand with two lumbrical muscles at each place where you’d ordinarily find only one, and the muscles inserted to adjacent digits. This anatomical variation is not at all uncommon. And if you’re born with this anatomical variation and choose to play lute, then the motions involved in virtuosic lute playing may place particularly great stresses on your aberrant anatomy, in ways that might not affect persons with conventional anatomy quite so severely.

DSM: So what’s going on when we retrain or ‘retune’ the biomechanics with Constraint-Induced Therapy or other physical therapy techniques?

CMT: Well, we learn independent ring and middle finger motion by altering how we activate the controlling networks in the brain, in the primary motor cortex. Neurons in motor cortex aren’t like house-wiring: they don’t make simple direct connections to individual muscles. Instead, our evolution as mammals has set us up to flex and extend our fingers together and to grasp things. Independent digit movements outside of the index finger and thumb require complex inter-neuron coordination to get the desired balance in muscle force at each joint.

Completely independent digit motion is the result of a complex pattern of activation that isolates a movement by preventing other movements mechanically and perhaps by inhibiting some muscles as well. This is why it takes lots of repetitions to learn such skills. Learning new motor skills changes the way muscles and movements are represented topographically among the cells of the motor cortex, and also the way sensory information is represented in the sensory cortex.

Here’s some anatomy, just to give you an idea of where things are, and why the geometry and biomechanics of the hand are so vulnerable as they are.

Crossection of hand, 4 fingers, distal to thumb

Upper Left

Lower Left

Lower Right

Upper Right

1. Distal palmar fat pad

2. First lumbrical m.

3. Tendons mm. flexors digitorum superficialis and profundus

4. Tendons mm. interosseous
and lumbrical

5. Proximal phalanx, second digit

6. Second lumbrical m.

7. Tendon extensor digitorum communis

8. Dorsal and palmar interosseous mm.

9. Tendon m. extensor indicis proprius

10. Collateral ligament

11. Tendons mm. interosseous
and lumbrical

12. Proximal phalanx, third digit

13. Tendon m. extensor digitorum communis

14. Tendons and mm. dorsal
and palmar interosseous

15. Tendons mm. interosseous
and lumbrical

16. Tendon m. extensor digitorum communis

17. Proximal phalanx, fourth digit

18. Tendons mm. interosseous
and lumbrical

19. Tendons mm. flexors digitorum
superficialis and profundus

20. Proximal phalanx, fifth digit

21. Articular capsule and collateral ligament

22. Interphalangeal joint

23. Middle phalanx, fifth digit

24. Fifth digit, distal segment fat pad

25. Fibrous digital sheath

26. Tendon m. flexor digitorum

The photomacrograph of a transverse whole-section of the hand passes through the four fingers. The slice is taken of a cadaver hand, a frozen section, distal to the thumb—right at the end of the hand, before the fingers start. You can see that the little finger is separated from the others, which makes sense if you look at your own hand. The gap between the little finger and the ring finger comes proximally further into the hand, compared to the gaps between the other fingers. The articulation (22) between the proximal (20) and middle (23) phalanges is seen in the cross-sectional slice in the picture above. This is a pretty bulky hand. Probably not the hand of a musician. But the image helps to give you and idea of the anatomical relationships just the same.

Notice how the extensor tendon to the ring (fourth) finger is very closely applied to its dorsal surface. Not much clearance there! The tendons and distal ends of both interosseous and lumbrical muscles (8, 11, 14, 15, 18) are identified in the picture in relation to the middle digit proximal phalanx (12). The first (2) and second (6) lumbricals are seen close to, and on the radial side of, their tendons of origin. The two lateral (first and second) lumbricals arise from the radial side of the palmer aspect of the first and second tendons of flexor digitorum profundus. The two medial (third and fourth) arise from adjacent sides of the second and third, and the third and fourth tendons of flexor digitorum profundus. The muscles insert into the radial border of the tendon of extensor digitorum on the back of the proximal phalanx. The compactness of this anatomy reveals why the mechanical leverage and pulley-and-lever structures are so exquisitely sensitive. The fulcrums for the action of the lumbricals on the phalanges operate at a relatively high mechanical advantage (force ratio), and therefore small disturbances in the muscles themselves or in the tendon bundle and the tendons’ insertion points can give rise to surprisingly large disturbances in the motion—velocity of attack and release, power, etc.—at the phalanx.

Principles of Neuroplasticity—Strategies for Rehabilitation for Focal Dystonia through Forced Use:
  • Based on the assumption that patients will more readily use the extremity that is normal (unaffected) unless you restrict it.
  • Forcing the use of the affected extremity will modify muscle structure and increase function.
  • Effective for pianists but not for guitarists or lutenists.

Constraint-Induced Therapy (Sensory Motor Retuning):
  • Elbert, Sterr, and colleagues studied 7 musicians with Focal Dystonia.
  • Forced use on the instrument with a splint that restricted the movement of each finger; 10 days, 7 hrs each day.
  • Six of 7 improved; less improvement for guitarists or lutenists than for pianists.

In the absence of a definitive diagnosis, the Physical Therapist or Rehabilitation Medicine practitioner may treat on an empirical basis:
  • Treat the initial injury as part of [an empirically conjectured—] inflammatory, healing process.
  • Decrease stress and stop negative abnormal patterns of movement.

At least in me, there are strong linkages between the middle and ring fingers when I attempt to flex the middle finger at the distal (end) joints. This probably involves mechanical linkages between the profundus muscles for those two fingers—linkages at the level of both proximal tendon and muscle. Nobody knows whether those linkages can evolve over time under conditions of high repetition stress or over-use.

DSM: Obviously, if inflammation is present, you’d expect that some fibrosis and linkage would occur as part of the healing and response to the inflammation.

CMT: But if no overt tendonitis or other inflammatory process is going on, it’s not clear whether a fibrotic proliferative reaction would occur, to give rise to the kind of symptoms your friend is experiencing. Assuming it’s not Focal Dystonia, the Constraint-Induced Therapy of “retuning” exercises can help to compensate for any abnormal anatomical linkages that might be in his hand. Best of luck to your lutenist friend!

Mentoring the Inner Chamber Musician

Bruce Pearson

I t just doesn’t seem that long since those days of not knowing what young musicians should or shouldn’t be able to do. Having had a ‘little more’ experience now, I am amazed that you and your classmates were able to play, pretty well, charts that were written for pros.”

  —  Bruce Pearson, reminiscing in 2007 about his early teaching in the late Sixties
CMT: It’s hard to know what someone should or shouldn’t be able to do at a particular point in her/his artistic development!

Angela Myles Beeching, New England Conservatory
DSM: Well, the fact is that you never know until you try. The brave thing involves enthusiastically “pushing the envelope” —both the teacher and the student are ideally doing this. Is there ever a teacher so wizened and hoary that the process with this student is not throwing off sparks of new pedagogy? I don’t think so. Every person is so open-ended and so different from every other person that the teaching or mentoring process is perpetually new and unique.

Danel Kvartetti, in sauna, in Kuhmo Finland, 2006
CMT: Unless burn-out or hubris sets in. With music especially—which, like mathematics and a few other virtuosic pursuits, is to a large degree a young person’s realm—there really ought not to be preconceptions as to what a person ‘should’ or ‘shouldn’t’ be able to do. No, you don’t want to put together young ensembles whose members’ abilities are light-years apart and frustrate them by putting literature in front of them that is at the level of the least-able lowest-common-denominator member. Nor do you want to frustrate them by giving them literature that’s at the level of the one prodigy in the ensemble. It’s truly an art: finding literature that adequately stretches the capabilities of each member, and then evolving that literature as the complexion of their abilities changes over the passing months together.

DSM: If there’re one or two reallly gifted players in the group, the lessons to be learned are a bit different for them than they are for the others, aren’t they! The issue becomes more one of balance and adaptation, accommodating one’s own playing to the realities of the notes around you. The elements of musicianship then have more to do with interpersonal communication. The stronger players, ideally, become sub-mentors—in some ways like the principal chairs in an orchestra. It’s very like the idea of ‘induction’, which has some cachet lately in the scholarly teaching/pedagogy journal literature.

CMT: Well, as Bruce Pearson says, there’s the [population epidemiology] of technic—an empirical distribution of abilities that one can reasonably expect in a given class. You’re delighted when you encounter abilities and synergies that are above the median. But you have no right to feel disappointed when you encounter deficiencies and dissension that are below it.

Lute Master Class
DSM: And, of course, it’s a matter not only for members of ensembles who are experiencing personnel changes, or for teachers or leaders of ensembles in an education setting, but also for the composers who are composing or arranging pieces. Music, like any other kind of literature, either finds its natural readership or else it doesn’t. The practical composer has, just as much as any good author, a clear sense of the epidemiology of technic—a clear sense of who is going to be able to play what she/he is writing; a clear sense of who is going to want to perform it, given the difficulties and risks that the composer builds into the piece. If you’re composing and are oblivious to this, you’ll be composing for a very small market—maybe a market of zero.

Young Piano Trio
CMT: Regardless of the ages of the ensemble’s members—and regardless of the natural norms for what middle school, or high school, or college students may generally be expected to do—I think chamber music is, like jazz, one of the genres most congenial to exploration. There are social supports and incentives in a string quartet, say—supports that you wouldn’t necessarily find in a one-on-one mentoring relationship with a viol master. Your failures are very visible, yes, but you are bathed in the empathy of the other members. And your successes have a tremendous immediacy and are shared in a way that is far more nourishing than the drier, more abstract appreciations that come in solo work or in larger orchestras. That was one of the lessons I learned from Bruce Pearson, back in the late Sixties.

Young Quartet, Amherst