Sensory Neuronopathy: Diagnostic Criteria
Abstract & Commentary
By Michael Rubin, MD, Professor of Clinical Neurology, Weill Cornell Medical College. Dr. Rubin reports that he receives grant/research support from Pfizer and is on the speaker's bureau of Athena Diagnostics.
Synopsis: Clinical criteria for sensory neuronopathy can reliably separate this syndrome from more distal, axonal syndromes.
Source: Camdessanche JP, Jousserand G, Ferraud K, et al. The pattern and diagnostic criteria of sensory neuronopathy: A case-control study. Brain doi:10.1093/brain/awp136.
Sensory neuronopathy or ganglionopathy may be idiopathic, but also presents as a paraneoplastic syndrome, or in association with Sjogren's syndrome, HIV infection, or connective tissue disorders. Sensory neuropathy not affecting the dorsal root ganglion (DRG) may be difficult to differentiate clinically from neuronopathy, while some conditions affect both the DRG and the sensory axon, underscoring the need for improved clinical criteria to enable accurate symptom localization to the DRG.
In this case-controlled, retrospective study of patients referred to the Rare Neuromuscular Disease Center in Rhone-Alpes, France, between 1993 and 2007, review of records was undertaken of 85 patients with paraneoplastic disorders and 511 patients with non-paraneoplastic sensory neuropathy. To be included for study, patients had to present with a clinically pure sensory neuropathy and have complete clinical and electrodiagnostic records on file. Biochemical studies included evaluation for diabetes, renal failure, monoclonal gammopathy, liver or thyroid disease, B12 deficiency, organ- or non-organ-specific antibodies, and onconeural antibodies. Patients with radiculopathy and entrapment or hereditary neuropathy were excluded. Patients with no alternative diagnosis for neuropathy other than paraneoplastic disease or cisplatin toxicity were classified as having definite sensory neuronopathy, and patients with a non-length-dependent, clinically pure sensory neuropathy were considered as having likely sensory neuronopathy. Patients with sensory neuropathy that was either length-dependent or clearly not neuronopathic, based on etiology or electrophysiology, served as controls. Statistical analysis included Fisher's exact test, Student's t-test, or the Wilcoxon Mann-Whitney test, and logistic regression.
Among 596 eligible patients, 518 were excluded based on selection criteria or incomplete data, leaving 134 with clinically pure sensory neuropathy, of which 78 had either unambiguous sensory neuronopathy (n = 44) or likely sensory neuronopathy (n = 34), and 56 had another form of neuropathy and served as controls. The control group consisted of immune-mediated etiologies (n = 16) comprising chronic inflammatory demyelinating polyneuropathy, distal demyelinating sensory neuropathy, vasculitis, Lewis-Sumner syndrome or Sjogren's syndrome, diabetes or B12 deficiency (four each), amyloid or hypothyroidism (one each), alcohol (n = 2), toxic (n = 6), or idiopathic (n = 24). Logistic regression allowed for the following combination of five significant diagnostic criteria for sensory neuronopathy to emerge: limb ataxia, asymmetric distribution, sensory loss other than in the legs, at least one absent or three low (< 30% of lower limit of normal) sensory action potentials in the arms, and fewer than two abnormal motor nerve conduction studies in the legs. Sensory neuropathy may be reliably localized to the DRG based on these criteria, permitting its differentiation from more distal sensory neuropathy syndromes.
Commentary
Subacute sensory neuronopathy (SSN), the classic paraneoplastic peripheral neuropathy commonly found in small cell lung cancer with anti-Hu antibodies, usually presents with asymmetric pain and paresthesiae, predominantly in the arms but evolving over days to weeks to include all four extremities, with sensory ataxia and pseudoathetoid movements of the hands. Cerebrospinal fluid studies may demonstrate elevated protein, pleocytosis, or oligoclonal bands. Patients with SSN and anti-Hu antibodies can also develop encephalomyelitis or limbic encephalitis, sometimes referred together as the anti-Hu syndrome. Destruction of the dorsal root ganglia by cytotoxic T-lymphocytes is the underlying mechanism, and explains the poor neurological outcome despite immunosuppressive therapy. Paraneoplastic sensory or sensorimotor neuropathy also occurs with anti-CV2 antibodies, usually with small cell lung cancer or thymoma, often with CNS dysfunction, and is characterized by an axonal or mixed axonal and demyelinating pattern on nerve conduction studies.
Clinical criteria for sensory neuronopathy can reliably separate this syndrome from more distal, axonal syndromes.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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