[The "pseudo-polyneuropathy" type sensory disturbances in cervical spondylotic myelopathy]

We reported the pseudo-polyneuropathy type sensory disturbances in cervical spondylotic myelopathy. We defined this clinical type by objective superficial sensory deficits of all four distal limbs, and excluded the patients having only subjective sensory disturbances. Ten out of 61 patients with cervical spondylotic myelopathy had sensory disturbances of this type. Two patients noticed difference of the subjective sensations of the upper and lower limbs. Eight patients developed sensory symptoms initially in the upper limbs. Pin-prick sensation was diminished in the upper limbs more predominantly than in the lower limbs. Vibration sense was affected in the lower limbs predominantly. Motor functions were mildly impaired, and muscle stretch reflex of triceps brachii was preserved in all ten patients. Distribution of sensory disturbances of four patients changed in their course. Nerve conduction studies and F-wave latencies were normal. Electromyography showed mild chronic denervation of the C5-C7 innervated muscles. Somatosensory evoked potentials after median or ulnar nerve stimulation showed delayed latencies or attenuated waveforms of N13 as well as P14 peaks. Spinal cord was compressed mainly at C4/5 and C5/6 intervertebral level, shown by myelography, CT-myelography or magnetic resonance imagings. We conclude that the pseudo-polyneuropathy type sensory disturbance of cervical spondylotic myelopathy indicates the lesion at mid-to-low cervical vertebral level. The anatomical substrates for this type of sensory impairment could be caused by combination of the dorsal horn/anterior comissure lesions for the upper limbs, and the anterolateral funiculi lesions for the lower limbs.