Glial bundles in spinal nerve roots

Summary

Glial bundles (GBs) in spinal nerve roots in 86 autopsy cases with various spinal lesions were examined using the peroxidase-antiperoxidase technique for glial fibrillary acidic protein (GFAP). In 19 of 22 cases of Werding-Hoffmann disease (WHD), GBs were present in the anterior roots (ARs) but absent in the youngest age group (age<1.5 months at death). GBs were numerous in classical cases (age 3–24 months), accompanying severe damage of the anterior horns and roots, but were less prominent in most cases of protracted course (age 2–8.5 years). Thus, development of GBs in the ARs of motor neuron disease at a young age seems to depend on the clinical type (age at onset and disease duration) and degree of damage to motor neurons and ARs.

Varying numbers of GBs were found also in the posterior roots (PRs) of 12 cases of WHD. In 13 patients with amyotrophic lateral sclerosis (ALS), few GBs were observed in the ARs of two and PRs of five cases without apparent relation to other clinicopathologic data. GBs in the PRs of both WHD and ALS might indicate spreading of the degenerative process to sensory neurons despite the absence of pathology detectable by routine histological stains.

Numerous GBs were found also in adults affected with polymyelitis in childhood. Varying numbers of GBs were present, however, in many different diseases, such as Friedreich ataxia, Guillain-Barré syndrome, various polyneuropathies, cervical spondylosis, ataxia telangiectasia, metachromatic leukodystrophy, and Leigh syndrome.

It is concluded that GBs are a characteristic but nonspecific reaction of the central-peripheral transition zone of the nervous system, which develops prominently in response to early damage of the myelinated fibres in the nerve roots. However, their absence in many cases of severe damage of the spinal roots renders their exact pathogenesis and significance still obscure.