Hirayama jc

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journal club on hirayama disease

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Hirayama jc

  1. 1. Bilaterally symmetric form of hirayama disese • Sunil Pradhan et al • Institute of human behavior and allied sciences, New delhi. • Neurology,vol.72,number 24,june16,2009.
  2. 2. background • Hirayama disease (benign juvenile brachial spinal muscular atrophy, benign juvenile muscular atrophy of distal upper extremity, monomelic amyotrophy). • Pure motor focal amyotrophy in distribution of c7,8,T1 spinal segments • Sporadic, Men, second and early third decade. • Muscular weakness and wasting of hand and forearm • Oblique amyotrophy. • Insidious onset, steadily progressive for 1-3 yrs..stable stage. • Dynamic cord compression during neck flexion. • Juvenile asymmetric segmental spinal muscular atrophy(JASSMA) • Describe bilaterally symmetric form of hirayama disease.
  3. 3. Materials and methods • 106 (m-103,f-3) • 14-32 yrs • Two academic centers • 1992-2008 • Patients registry • 11 patients with symmetic form • Clinical, edx, mri evaluation normal and neck flexion.
  4. 4. criteria • Onset in teen and early 20s. • Symmetric /asymmetric muscle atrophy in c7,c8,t1 myotome. • No sensory symptoms/signs • Relative sparing of brachioradialis • Tremulousness of fingers in outstretched hands • Cold paresis • Unilaterality ….replaced by MRI findigs
  5. 5. MRI criteria • Flattening of spinal cord against c5-6 vertebral bodies • Forward movement of posterior cervical duramater, • reduction in size of posterior cervical subarachnoid space. • Contrast enhancing crescent shaped posterior cervical epidural pace.
  6. 6. EMG • 1st dorsalinterossei,APB,EDC,brachioradialis,biceps,vastu s lateralis,tibialis anterior. • Denervation potentials( positive sharp waves and otentials)during rest state were compared in same muscle in two sides. • Reinervation potentials (large,wide polyphasic potentials)studied in mild contraction in each muscle(3 x3) • 10 sweeps of 100 msec duration-frozen –percent of polyphasic potentials to number of MUP and compared.
  7. 7. NCS • CMAP of median,ulnar,radial nerve were used to document symmetry of disease. • < 20% difference in CMAP of APB,ADM,EDC taken as symmetrical. • SNC to rule out axonal forms of polyneuropathy • All findings were compared with existing knowledge of the disease
  8. 8. results • 11/106 symmetrical • All male • Age 18-24(20.27) • Started at mean 17.8 yrs progresed for 1-3 yrs (9),3-4 yrs (2) • 9 immunised for polio, none had h/o polio. • 6 had onset in winter months • None had preceding febrile illness • All had weakness and wasting in c5,6 t1 myotomes • 6 had partial brachioradialis wasting s/o c6 myotome
  9. 9. • Unilateral onset in 9 patients (R 6, L 3),bilateral in two. • Autonomic dysfunction in all, (excessive sweating in 7,cold hands in 8,hair loss in 5) • All had fasciculation at rest ,mini polymyoclonus in outstretched hands. • 7 had brisk DTR in lower limbs
  10. 10. mri • Neutral position-Symmetric cord atrophy in 9, T2 hyper intensity in anterior lateral aspect of lower cervical spinal cord in 7. • Neck flexion-band like cord flattening in all (symmetric in 7,asymmetric in 4)crescent shaped enhancing epidural in all.
  11. 11. EDX • All had N SNAPs • All had n emg in lower limbs • All clinicallly symmetric form had < 20% difference in CMAPs. • Quantitative asessment of percentage of acute denervation and chronic renervation potentials showed nearly symmetric involvement between right and left
  12. 12. discussion • In this series of 106 patients nearly 10% showed symmetric involvement of both upperlimbs. • VS a form of ALS ‘brachial amyotrophic diplegia’ ‘flail arm syndrome’ ‘man in barrel syndrome’-older age, predominant c5-6 involvement, overt fasciculations, gradual appearance of UMN or bulbar signs,avg survival of 5 yrs,no dynamic MRI changes with neck flexion. • Vs postpolio atrophy-no h/o polio,symmetrical and MRI.
  13. 13. • Short length of cervical dural canal that cannot compensate for flexion related increased length of vertebral canal. dural canal becomes tight during neck flexion-anterior displacement of posterior dural wall and spinal cord, spinal cord gets flattened against c5-6 vertebral body,cresent shaped posterior epidural space with prominent venous plexus. • Neck flexion related anatomic changes cause mechanical and hemodynamic stress on anterior horn cells in c7,8,T1 • Severe form of hirayama disease
  14. 14. • Thank you

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