The patient presents with fatigue, postprandial nausea, diarrhea, food allergies, and nighttime tachycardia. She was diagnosed with mast cell syndrome (MCAS). Autonomic testing has shown anxiety; mild postural tachycardia syndrome (POTS), neuropathic form; and small fiber neuropathy, mixed, length-dependent.
Autonomic testing showed mixed small fiber neuropathy, which can be responsible for both sensory complaints and dysautonomia. Dysautonomia was generalized but mild. The patient has generalized hypermobility spectrum disorder (GHSD).
Patient became unresponsive during the first minute of the tilt; she was tachycardic but the blood pressure and cerebral blood flow were stable. Psychogenic pseudosyncope can be superimposed on postural tachycardia syndrome (POTS). Pseudosyncope, small fiber neuropathy, and POTS can be associated with hypermobile Ehlers-Danlos syndrome.
The tilt test showed a combination of anxiety, postural tachycardia syndrome (POTS), and presyncope. The POTS in this patient was mild, but anxiety may exacerbate symptoms.
Small fiber neuropathy, mixed, length-dependent can be autoimmune even if no antineuronal antibodies can be found. Yet the seronegative small fiber neuropathy may still respond to therapy with immune globulins.
Small fiber neuropathy, mixed, length-dependent, is associated with antibodies against the N-type calcium channel. Tilt showed hypocapnic cerebral hypoperfusion.
This case demonstrates severe autonomic failure with orthostatic hypotension affecting cardiovagal and sympathetic adrenergic fibers and associated with small fiber neuropathy. Small fiber neuropathy is severe, mixed, and affecting sensory and autonomic fibers, non–length-dependent. Orthostatic cerebral blood flow velocity was reduced throughout the tilt, indicative of autoregulation failure.
This case describes neuropathic postural tachycardia syndrome (POTS) with striational antibodies that can be associated with small fiber neuropathy and respond to IVIG.
This patient is an example of a typical autonomic failure associated with diabetes mellitus. Autonomic testing showed generalized autonomic failure with orthostatic hypotension and severe small fiber neuropathy affecting both sensory and autonomic fibers.
