Sensory conduction study in chronic sensory ataxic neuropathy

Clinicopathological features of acute autonomic and sensory neuropathy

Acute autonomic and sensory neuropathy is a rare disorder that has been only anecdotally reported. We characterized the clinical, electrophysiological, pathological and prognostic features of 21 patients with acute autonomic and sensory neuropathy. An antecedent event, mostly an upper respiratory tract or gastrointestinal tract infection, was reported in two-thirds of patients. Profound autonomic failure with various degrees of sensory impairment characterized the neuropathic features in all patients. The initial symptoms were those related to autonomic disturbance or superficial sensory impairment in all patients, while deep sensory impairment accompanied by sensory ataxia subsequently appeared in 12 patients. The severity of sensory ataxia tended to become worse as the duration from the onset to the peak phase of neuropathy became longer (P<0.001). The distribution of sensory manifestations included the proximal regions of the limbs, face, scalp and trunk in most patients. It tended to be asymmetrical and segmental, rather than presenting as a symmetric polyneuropathy. Pain of the involved region was a common and serious symptom. In addition to autonomic and sensory symptoms, coughing episodes, psychiatric symptoms, sleep apnoea and aspiration, pneumonia made it difficult to manage the clinical condition. Nerve conduction studies revealed the reduction of sensory nerve action potentials in patients with sensory ataxia, while it was relatively preserved in patients without sensory ataxia. Magnetic resonance imaging of the spinal cord revealed a high-intensity area in the posterior column on T(2)*-weighted gradient echo image in patients with sensory ataxia but not in those without it. Sural nerve biopsy revealed small-fibre predominant axonal loss without evidence of nerve regeneration. In an autopsy case with impairment of both superficial and deep sensations, we observed severe neuronal cell loss in the thoracic sympathetic and dorsal root ganglia, and Auerbach's plexus with well preserved anterior hone cells. Myelinated fibres in the anterior spinal root were preserved, while those in the posterior spinal root and the posterior column of the spinal cord were depleted. Although recovery of sensory impairment was poor, autonomic dysfunction was ameliorated to some degree within several months in most patients. In conclusion, an immune-mediated mechanism may be associated with acute autonomic and sensory neuropathy. Small neuronal cells in the autonomic and sensory ganglia may be affected in the initial phase, and subsequently, large neuronal cells in the sensory ganglia are damaged.

The wide spectrum of clinical manifestations in Sjögren's syndrome-associated neuropathy

We assessed the clinicopathological features of 92 patients with primary Sjögren's syndrome-associated neuropathy (76 women, 16 men, 54.7 years, age at onset). The majority of patients (93%) were diagnosed with Sjögren's syndrome after neuropathic symptoms appeared. We classified these patients into seven forms of neuropathy: sensory ataxic neuropathy (n = 36), painful sensory neuropathy without sensory ataxia (n = 18), multiple mononeuropathy (n = 11), multiple cranial neuropathy (n = 5), trigeminal neuropathy (n = 15), autonomic neuropathy (n = 3) and radiculoneuropathy (n = 4), based on the predominant neuropathic symptoms. Acute or subacute onset was seen more frequently in multiple mononeuropathy and multiple cranial neuropathy, whereas chronic progression was predominant in other forms of neuropathy. Sensory symptoms without substantial motor involvement were seen predominantly in sensory ataxic, painful sensory, trigeminal and autonomic neuropathy, although the affected sensory modalities and distribution pattern varied. In contrast, motor weakness and muscle atrophy were observed in multiple mononeuropathy, multiple cranial neuropathy and radiculoneuropathy. Autonomic symptoms were often seen in all forms of neuropathy. Abnormal pupils and orthostatic hypotension were particularly frequent in sensory ataxic, painful, trigeminal and autonomic neuropathy. Unelicited somatosensory evoked potentials and spinal cord posterior column abnormalities in MRI were observed in sensory ataxic, painful and autonomic neuropathy. Sural nerve biopsy specimens (n = 55) revealed variable degrees of axon loss. Predominantly large fibre loss was observed in sensory ataxic neuropathy, whereas predominantly small fibre loss occurred in painful sensory neuropathy. Angiitis and perivascular cell invasion were seen most frequently in multiple mononeuropathy, followed by sensory ataxic neuropathy. The autopsy findings of one patient with sensory ataxic neuropathy showed severe large sensory neuron loss paralleling to dorsal root and posterior column involvement of the spinal cord, and severe sympathetic neuron loss. Degrees of neuron loss in the dorsal and sympathetic ganglion corresponded to segmental distribution of sensory and sweating impairment. Multifocal T-cell invasion was seen in the dorsal root and sympathetic ganglion, perineurial space and vessel walls in the nerve trunks. Differential therapeutic responses for corticosteroids and IVIg were seen among the neuropathic forms. These clinicopathological observations suggest that sensory ataxic, painful and perhaps trigeminal neuropathy are related to ganglioneuronopathic process, whereas multiple mononeuropathy and multiple cranial neuropathy would be more closely associated with vasculitic process.

Sensory neuron diseases

Sensory neuron diseases (SND) are a distinct subgroup of peripheral-nervous-system diseases, first acknowledged in 1948. Acquired SND have a subacute or chronic course and are associated with systemic immune-mediated diseases, vitamin intoxication or deficiency, neurotoxic drugs, and life-threatening diseases such as cancer. SND are commonly idiopathic but can be genetic diseases; the latter tend to involve subtypes of sensory neurons and are associated with certain clinical pictures. The loss of sensory neurons in dorsal root ganglia causes the degeneration of short and long peripheral axons and central sensory projections in the posterior columns. This pathological process leads to a pattern of sensory nerve degeneration that is not length dependent and explains distinct clinical and neurophysiological abnormalities. Here we propose a comprehensive approach to the diagnosis of acquired and hereditary SND and discuss clinical, genetic, neurophysiological, neuroradiological, and neuropathological assessments.

[Electrophysiologic study, diagnosis and cases of acquired sensory polyneuropathy]

Sensory neuropathies encompass a group of neuropathies affecting solely or predominantly peripheral sensory nerves. They are rarely encountered in clinical practice. The authors review sensory nerve conduction studies and compare the various recording technics. Values of compound sensory action potential amplitude and sensory nerve conduction velocity are analyzed. On the basis of clinical and electrophysiological sensory impairment, three types of neuropathies can be proposed: neuropathies with either large, small or total myelinated fibers involvement. Lastly definable causes of sensory neuropathies are reviewed.

[Involvements of the peripheral nervous system and primary Gougerot-Sjögren syndrome]

Peripheral neuropathy in primary Sjögren's syndrome is common although often unrecognized in mild forms of this affection. They are characterized by a predominently sensory deficiency and can be divided in several entities, of which the most important are: axonal distal symmetric polyneuropathy, either of sensory or sensory-motor presentation, which are supposed to be consecutive to ischemia induced by the vasculitis of the vasa nervorum; sensory neuronopathy mimicking the paraneoplastic syndromes from a clinical and electrophysiological point of view which are supposed to be linked to neuronal degeneration secondary to a lymphocytic infiltration of the dorsal root and ganglia; trigeminal sensory neuropathy, either alone or associated with one of the previously cited forms. The prescribed courses of etiological treatment consisting of corticosteroids and immunosuppressive agents are only effective in some acute forms. Tracking down systematically these peripheral neuropathies in patients affected by Sjögren's syndrome is the best way to recognize them. Alternatively, patients with unexplained neuropathies should be evaluated for the presence of Sjögren's syndrome.

Clinico-pathophysiological features of acute autonomic and sensory neuropathy: a long-term follow-up study

We evaluated the clinico-pathophysiological features of three patients with acute autonomic and sensory neuropathy (AASN) who were followed for over 3 years. Signs of an autonomic disturbance including vomiting, anhidrosis, urinary disturbances, orthostatic hypotension and reduced coefficient of variation of the R-R interval on electrocardiography gradually improved about 1 year after onset. However, all three exhibited severe generalized sensory impairment for all modalities with the development of persistent sensory ataxia. No sensory nerve action potentials could be elicited and no somatosensory evoked potentials could be obtained. Sural nerve biopsy revealed severe axonopathy. In two patients, a high-intensity area was observed in the posterior column of the spinal cord on T2*-weighted axial magnetic resonance images. The level of neuron-specific enolase in cerebrospinal fluid was markedly elevated in two patients, indicating spinal nerve root or sensory neuron damage. Motor nerve function was well preserved in all patients. Our findings suggests that the major lesion in patients with AASN, particularly those with a sensory deficit, is present in the dorsal root ganglion neurons, that is there is a ganglioneuronopathy.