title: Painless diabetic motor neuropathy: a variant of diabetic lumbosacral radiculoplexus Neuropathy?
abstract: OBJECTIVE
  Occasionally, diabetic patients develop painless, lower-limb, motor predominant neuropathy. Whether this is a variant of diabetic lumbosacral radiculoplexus neuropathy (DLRPN) (a painful disorder from ischemic injury and microvasculitis), a variant of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) or another disorder is unsettled. Here, we characterize the clinical and pathological features of painless diabetic motor predominant neuropathy.
  
  
  METHODS
  We identified patients with this syndrome who underwent nerve biopsy. We compared pathological features to 33 DLRPN and 25 CIDP biopsies.
  
  
  RESULTS
  23 patients were identified (22 had type 2 diabetes mellitus); 12 men; median age 62.2 years (range 36-78); median weight loss 30 pounds (range 0-100). Overall, the clinical features were similar to DLRPN except painless patients had more symmetrical and upper limb involvement, with slower progression and more severe impairment. Physiological testing demonstrated pan-modality sensory loss, autonomic abnormalities and axonal polyradiculoneuropathies. Nerve biopsies were similar to DLPRN showing ischemic injury (multifocal fiber loss [11/23], perineural thickening [18/23], injury neuroma [11/23], neovascularization [17/23]) and evidence of altered immunity and microvasculitis (epineurial perivascular inflammation [23/23], prior bleeding [11/23], vessel wall inflammation [15/23], and microvasculitis [3/23]). In contrast, CIDP biopsies did not show ischemic injury or microvasculitis but revealed demyelination and onion-bulbs.
  
  
  CONCLUSIONS
  1) Painless diabetic motor neuropathy is painless DLRPN and not CIDP and is caused by ischemic injury and microvasculitis. 2) The clinical features of painless DLRPN are different from typical DLPRN being more insidious and symmetrical with slower evolution. 3) The slower evolution may explain the lack of pain.
authors.affiliation: Servicio de Neurologia, Hospital Universitario La Fe, Valencia, Spain.
authors.forename: Mercedes
authors.initials: M
authors.lastname: Garces-Sanchez
authors.forename: Ruple S
authors.initials: RS
authors.lastname: Laughlin
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Dyck
authors.forename: JaNean K
authors.initials: JK
authors.lastname: Engelstad
authors.forename: Jane E
authors.initials: JE
authors.lastname: Norell
authors.forename: P James B
authors.initials: PJ
authors.lastname: Dyck
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000328:Adult; D000368:Aged; D003924:Diabetes Mellitus, Type 2 / Q000150:complications / Q000473:pathology*; D003929:Diabetic Neuropathies / Q000150:complications* / Q000473:pathology; D004576:Electromyography; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008160:Lumbosacral Plexus / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009069:Movement Disorders / Q000209:etiology* / Q000473:pathology; D009431:Neural Conduction / Q000502:physiology; D020277:Polyradiculoneuropathy, Chronic Inflammatory Demyelinating / Q000150:complications / Q000473:pathology; D011843:Radiculopathy / Q000150:complications*; D012720:Severity of Illness Index