Anhidrosis: A clue to an underlying autonomic disorder

Uncommon side effects of common drugs in patients with familial dysautonomia

PURPOSE

Patients with the autosomal recessive disorder of familial dysautonomia typically exhibit exacerbated adverse side effects to many common drugs. We aimed to catalog these adverse effects - with a focus on common drugs that are frequently administered to FD patients and compare their incidences to those within the general population.

METHODS

We used data of 595 FD patients from an international database with information on drugs received and adverse effects. To investigate the molecular causes of reported differences in drug responses in FD patients, we used expression microarrays to compare the mRNA expression profiles in peripheral blood leukocytes of FD patients (n = 12) and healthy individuals (n = 10).

RESULTS

Several drug classes, including cholinergics, anti-cholinergics, anti-convulsants, methylxanthines, SSRIs, and antibiotics caused either unreported symptoms or elevated rates of adverse events in FD patients. FD patients experienced different or more frequent adverse side effects than the general population in 31/123 drugs. These side effects included blood cell dyscrasias, amenorrhea, gastrointestinal bleeding, and bronchospasm. New findings include enhanced reaction of FD patients to H2 antagonist agents and to serotonin receptor agonists. We also detected eight genes differentially expressed between FD patients and healthy individuals that may underlie the differential drug responses of FD patients.

CONCLUSION

We provide evidence that suggests the use of several common drugs should be discontinued or reduced in FD patients.

Ross Syndrome: A Patient with a 23-Year History

We present a 60-year-old female with a 23-year history of anhidrosis with concomitant heat intolerance. At examination, we found a right-sided tonic pupil, absent tendon reflexes, and a segmental patch of compensatory hyperhidrosis in the left lower quadrant of her trunk. To further confirm this finding, a minor test (a starch-iodine test, which is used to evaluate the sudomotor function, sweating) was performed. Nerve conduction studies revealed evidence of a mild distal sensory polyneuropathy of the axonal type. Tilt-table testing showed signs of orthostatic hypotension with evidence of reduced sympathetic function. Skin biopsy excluded pathology in the sweat glands. Our patient met the criteria for a diagnosis of Ross syndrome. This case describes the long-term outcome of this rare entity and highlights how careful examination and bedside autonomic testing can confirm the diagnosis of autonomic neurological disorders.

Asymptomatic Severe Vagal and Sympathetic Cardiac Denervation in Holmes-Adie's Syndrome

A 40-year-old woman was found to have bilateral Adie's pupils and generalized muscle stretch areflexia. She did not have orthostatic hypotension but, in an ECG strip in the office, she appeared to have an almost fixed heart rate. We thus studied the heart rate variability (HRV) and the systolic blood pressure variability (SBPV) in supine and standing position and also during rhythmic breathing. We found a decreased HRV in the time domain with very low standard deviation in supine and standing position and during rhythmic breathing. HRV in the frequency domain was low with a decrease in the absolute power of HF and LF and a decrease in the sympathovagal balance in supine and standing positions. SBPV in the time and frequency domains was found to be normal. This patient with Holmes-Adie syndrome had an asymptomatic severe loss of HRV and a preserved SBPV. The global decrease in the HRV in the time and frequency domains indicated that she had both vagal and sympathetic cardiac denervation, whereas the preserved SBPV suggested normal innervation of the blood vessels.

Pupillary function in early multiple sclerosis

Autonomic pupillary function was assessed with pupillometry in 95 mildly or moderately disabled patients with multiple sclerosis (MS) and 81 healthy subjects. The parasympathetic pupillary function was measured as initial diameter (mm), time to minimum diameter (seconds), reflex amplitude (mm), relative reflex amplitude (%), and maximal constriction velocity (mm/seconds). To reflect the sympathetic pupillary function maximal redilatation velocity (mm/seconds), and time of 75% of redilatation (seconds) were measured. Of MS patients 85-99% were within the reference values of healthy subjects. In MS patients the effect of age was observed in the initial diameter, reflex amplitude, and time of 75% redilatation. There were no such age related effects in healthy subjects. In age adjusted analysis the initial diameter and time of 75% redilatation differed significantly from healthy controls. Autonomic pupillary functions were not associated with fatigue, visual defect, or bladder disturbance, as measured by Fatigue Severity Scale, Kurtzke's Functional System Scales, Expanded Disability Status Scale, or the Multiple Sclerosis Functional Composite. Our results suggest that both parasympathetic and sympathetic pupillary functions are disturbed already early in the course of MS. However, the disturbance is not severe at this stage of the disease. The dysfunction is age-dependent and thus possibly related to the dimished remyelination capacity of the central nervous system.