vincristine neuropathy nuggets and pearls

Verstappen CCP,Heimans Koeppen S, et al. JJ,  Dose-related vincristine-induced peripheral neuropathy with unexpected off-therapy worseningNeurology March 22, 2005 vol. 64 no. 6 1076-1077

 

Article described microtubule related neuropathy due to vincristine in 114 patients. 

 

1.  High dose group experienced more signs and symptoms than low dose group.

2.  Off therapy worsening signs and symptoms occurred in about 30 percent, mostly in the first month off. Most patients improved off therapy however.

3.  Paresthesias and numbness in both groups developed earlier in hands than feel and were more prominent in hands

4.  Paresthesias, numbness and pain occurred at more than 50 percent in both groups

5.  Resulting physical limitations include trouble buttoning clothes, climbing stairs, writing and walking

6. The dose intensity of VCR has changed considerably over the years. Studies 30 years ago describe dose intensities of 2 to 4 mg/week, frequently leading to a severe mixed sensorimotor peripheral neuropathy.Today, VCR is usually administered in a dose of ≤2 mg once every 1 to 4 weeks.

7.  Off therapy deterioration is also well described in cisplatin and paclitaxol related neuropathy.

 

 

 

 

EMG is the practice of medicine Position statement of the American Academy of Neurology

What is the issue?


Needle EMG is a diagnostic neuromuscular exam that is used to identify potentially serious neuromuscular diseases ranging from carpal tunnel syndrome to Lou Gehrig's Disease. Despite the inherently diagnostic nature of these exams, non-physicians have been aggressively seeking the authority to perform these tests. Patients should know that only physicians should perform an intrusive, complex and intrinsically diagnostic test.



Why is it important?

To be properly performed, needle EMG requires physician training, including an in-depth knowledge of neuromuscular diseases. Also, EMG tests are dynamic and depend upon the observations of the examiner. A physician must be present to see what is happening and decide on the next step in the test, as there is no way to know after the fact whether the test was performed correctly. Misdiagnosis can mean delayed or inappropriate treatment (including surgery) and diminished quality of life.



What is the Academy's position?

The AAN Professional Association (Academy) opposes efforts by non-physicians to permit the performance of needle EMG by non-physicians.



What can you do to help?

The Academy has developed an advocacy toolkit (to the right) to help you advocate on this important issue.





North Carolina

Legislation in North Carolina that revises the North Carolina Physical Therapy Act includes language that states physical therapy can include "the performance of electrodiagnostic, electrophysiologic, and other specialized tests of neuromuscular function or physical capacities."

Anti sulfatide neuropathies

clinical presentation is that of chronic axonal distal sensory neuropathy,symmetric, slowly progressive,  with pain in half and much less having any weakness. The frequency in idiopathic PN is only 0.7 %, but may be as high as 25 % in certain subgroups.  High titers are relatively specific for distal sensory neuropathy, whereas low titers can be seen in other conditons, including ITP, HIV, and autoimmune hepatitis.  Monoclonal gammopathies occur in half. 


GALOP (gait disorder, antibody, late age onset neuropathy) is a subgroup of antisulfatide neuropathy have monoclonal IgM  and antibodies to sulfatide and GALOP. 

anti GM1 antibodies pearls

1.  MMN with conduction block presents as asymmetric, painless, slowly progressive weakness especially in distal upper limbs. 
2.  Sensory sparing resembles ALS, however, UMN signs are not seen in MMN
3.   Conduction block outside of normal compression sites differentiates MMN and ALS.  Patients without conducton block occassionally respond to immunotherapy (Neurology 1997 first author JS Katz).
4. High titer IgM anti GM1 are seen in 50-60 percent of patients with MMN, but sensitivity is increased to 80-90 percent by complexing GM1 to secondary antigens co GM1 antibody test (Pestronk, Neurology 1997)
5.  In GBS, anti GM1 antibodies closely correlate with Campylobacter jejuni infection and sometimes correlate with worse neuropathy and outcome
6.  Other antigens coexpressed sometimes in GBS are GD1a, GD1b and GM2; some have argued GM2 correlates with CMV neuropathy but this is not univerally accepted.  GD1a is often seen in AMAN, the Chinese GBS variant (60 %) v. only 4 % of traditional GBS patients

Antibody related neuropathies anti MAG pearls

1.  typical presentation is distal symmetric slowly progressive sensorimotor neuropathy
2.  Half of patients with PN and IgM gammopathy have an autoantibody to MAG, typically kappa chain
3.  Antibody may cross react with SGPG
4.  Prolonged distal motor latencies are the most reliable finding, seen in 90 %
5.  Patients with a positive anti MAG confirmed by Western blot sugggests immune related PN
6.  If patients fulfil criteria for CIDP they should be so treated
7.  Patients with significant deficit should have immune therapy attempted even though it is likely to disappoint.
8.  Relationship to myeloma exists
9.  MGUS beyond  hematology read here http://neurologyminutiae.blogspot.com/2009/10/mgus-significant-beyond-hematology.html ;  malignant transformation here http://neurologyminutiae.blogspot.com/2007/04/malignant-transformation-of-monoclonal.html  ;  http://neurologyminutiae.blogspot.com/2007/04/malignant-transformation-in-mgus.html ; miscellany on MGUS prevalence here http://neurologyminutiae.blogspot.com/2006/08/miscellany-on-neuropathy-tests.html

Isolated tibial paralysis

Usually due to lesions below the popliteal space such as gunshot, knife wound, auto accident, or leg fractures.  Affects plantar flexion, ankle inversion, foot adduction.  Dorsiflexion may be affected due to contractures of  the anterior tibialis.  Sensation is lost over the heel, lateral border, ungual surfaces, Edema is usual with causalgia, trophic changes, and trophic ulcers.  Partial lesions may spare the calf muscles and affect only the muscles of the foot, usually with prominent pain. 

Obturator neurpathy

Clinical presentation is weakness of externally rotating, or adducting the thigh, or crossing the legs. Sensory involvement is minor.  Small areas of skin over the hip joint and the interior middle of thigh may have sensory loss. 

Anatomically, the posterior branch innervates the obturator externa and adductor magnus.  The anterior branch innervates the adductor longus and brevis and gracilis.  Both come from L2-4 lumbar plexus and are affected by same processes as femoral neuropathy, such as gravid uterus.

Howship-Romberg syndrome (historical) refers to pressure on obturator nerve by a rare obturator hernia.  It consists of pain that radiates down the thigh and is most marked at the knee.

Mononeuropathies

this post in intended to spur further of my own research.  Reading some of my dad's old 1950's vintage neurology books, mononeuropathies are due to lead poisoning, after typhus, influenza, or malaria. Will need to look up more about postinfectious neuropathies.

Dystrophinopathy clinical diagnostic pearls in adults

1. BMD (Becker's) may present in adulthood up to age 50+. Like DMD, earliest muscles involved are glutei, thigh abductors, and triceps, followed by quadriceps, deltoids, tibialis anterior, and last, biceps. Neck FLEXOR weakness is common.

2. The use of prednisone, annual cardiac and pulmonary (including sleep testing) evaluations have made children with DMD survive into the third decade.

3. Muscle cramps with aches during exercise are presentations of BMD during and after teenagehood. Isolated quadriceps involvement in the fifth decade may prompt a confusion with inclusion body myositis.

4. Isolated cardiac failure or even transplantation may occur prior to a diagnosis being made. Decreased LVEF or arrythmias are more common in BMD. X linked dilated cardiomyopathy is a rare form restricted to cardiac muscle with completely normal skeletal muscle, due to mutations that only affect the isoforms of cardiac muscle. Endocardial biopsy is required, and there is 50 % five year mortality without transplantation.

5. Other asymptomatic/minimally symptomatic clinical findings include exertional intolerance, elevated CPK, myalgias, myoglobinuria, none of which are mandatory. Other subtleties include calf and tongue hypertrophy, myopathic EMG, history of clumsiness or toe walking as a child,  and positive family history.

6. Ten percent of female carriers will be symptomatic, many minimally so, and manifest cases will be more likely to have diagnostic mutation on X chromosome. Some may have negative result, and need to be counselled regarding regarding a mutation only expressed in oocytes (germline mutation). For these patients prenatal testing is available (amniocentesis, eg. and others).

7. Coexisting Turners syndrome (XO) or skewed or nonrandom mutation of an X chromosome can cause full blown disease in a female carrier (DMD phenotype).

8. Cognitive disorders are common see http://behavioralneurologynotes.blogspot.com/2010/01/cognition-and-dystrophinopathy.html

9. Annual PSG (polysomnograms) are needed once patients are nonambulatory. Problems with dream sleep are common.

10. GI issues include GI pseudoobstruction in patients on continuous ventilation. This can be relieved by a regular bowel routine, continual low suction, placement of a second jejunal feeding tube. Late, swallowing issues might include positioning for swallowing, and restricted jaw movement due to masseter involvement.