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We appreciate the results of the study by van Dijket al 1 and add some results of our own regarding peripheral neuropathy and primary Sjögren’s syndrome.
The proportion of patients who fulfil the diagnostic criteria for Sjögren’s syndrome certainly depends on disease classification. Grant et al propose a distinct syndrome which includes patients with peripheral neuropathy and sicca complex.2 In their study minor salivary gland biopsy was positive in 73% of patients, which is in accordance with our studies.3 4 In our studies and those of Grantet al 2 labial gland biopsy was not performed until sicca symptoms were established. This supports the desirability of searching for a non-invasive test which should replace salivary gland biopsy.
In our study of 44 patients with chronic axonal neuropathy of small nerve fibres primary Sjögren’s syndrome was confirmed in 23%. The smaller proportion (4.6%) found by van Dijk et al 1 can be explained by the strict criteria used by inclusion of patients in our study. In other papers we stress the use of psychophysical methods besides routine electrophysiological tests in primary Sjögren’s syndrome.3 4 It seems that Dijket al 1 as well as Grantet al 2 ignored a group of patients with small nerve fibre involvement lacking the psychophysical assessment of thermal specific and thermal pain sensitivity as well as electrophysical evaluation of the autonomic nervous system.
We agree with the authors that in patients with peripheral neuropathy sicca symptoms are often unrecognised. All of our patients were referred to the outpatient’s clinic because of positive sensory symptoms. Mainly they had burning pain. In most patients routine electrophysiological findings were within normal limits whereas thermal specific and thermal pain sensitivity assessment as well as electrophysiological determination of autonomic nervous system function disclosed distinct abnormalities.
We are aware that there is no specific test to evaluate Sjögren’s syndrome or peripheral neuropathy with sicca complex as defined by Kennett and Harding.5 However, there is no reason to perform labial gland biopsy in each patient with chronic idiopathic axonal neuropathy as described in the study of van Dijket al.1 Finally, we want to stress the need for a non-invasive method for diagnosing Sjögren’s syndrome.3
We thank Denišlič and Meh for their comments on our study regarding Sjögren’s syndrome in patients with chronic idiopathic axonal polyneuropathy (CIAP).1-1 As another example of the wide range of peripheral nerve disorders in Sjögren’s syndrome, they stress the importance of recognising patients with small nerve fibre disease. We agree that these patients were excluded from our study, as axonal nerve fibre dysfunction on electrophysiological examination was required to confirm the clinical diagnosis of polyneuropathy in our study, and the routine neurophysiological investigations often do not show abnormalities in patients with small nerve fibre disease. When small nerve fibre dysfunction of unknown cause is present, we also perform an investigation for Sjögren’s syndrome as we described .
We do not recommend performing a labial salivary gland biopsy in every patient with CIAP. As in the figure, we suggest performing further tests for Sjögren’s syndrome in men with CIAP only when ocular or oral sicca symptoms are present and only a labial salivary gland biopsy when objective tests for tear gland and salivary gland dysfunction or serological abnormalities are also present. However, in women with CIAP we suggest a full investigation for Sjögren’s syndrome that includes a questionnaire for ocular and oral symptoms, a Schirmer’s test or Rose bengal staining score, and determination of serological abnormalities; when an abnormal result is found in any of these tests, a sublabial salivary gland biopsy should be performed to see if a diagnosis of Sjögren’s syndrome can be made.