PMC5308420_01
(a-c) Neurological examination at the age of 13 years shows marked weakness on extension of the index and middle finger on both sides and on abduction of the left thumb. At the age of 14 years, (d and e) the pattern of the weakness has not changed; the weakness is bit more pronounced, but has been stable in the last 6 months. (c and e) Marked atrophy of the right thenar and to a lesser degree of the other intrinsic hand muscles can be seen. Spinal MRI (T2-weighted images) at the age of 14 years shows flattening of the lower cervical cord at vertebral levels C5 to C7 on sagittal images in neutral position (f) with a spinal canal anterior-posterior diameter of 9.5 mm and in neck flexion (g) with a spinal canal diameter of 7.3 mm measured at C6/7. On axial images in neck flexion (i, at level C5/C6), the anterior-posterior diameter of the lower cervical myelon is diminished to less than 5 mm. (g and i) Also a slight signal hyperintensity in the ventral myelon can be seen extending from vertebral levels C5 to C7. (h) On the axial image at a higher vertebral level (C3/C4), no abnormality of the cord can be seen.
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Neurological examination at the age of 13 years revealed marked weakness (MRC 2 to 3-) for extension of the index and middle fingers bilaterally and for abduction of the left thumb (Figure 1(a)-(c)). At the age of 14 years (Figure 1(d) and (e)), the pattern of weakness and wasting was unchanged but severity of weakness had slightly increased, being stable during the last 6 months. MUAPs indicating chronic denervation. Magnetic resonance imaging (MRI) of the cervical spine in an orthotopic head position (Figure 1(f)) and under head anteflexion (Figure 1(g) and (i)) showed flattening and a slight intramedullary signal alteration of the myelon between segments C5 and C7.