The pattern of cutaneous innervation of the human foot

Neurotransmitters, neuropeptides and their receptors interact with immune response in healthy and psoriatic skin

Psoriasis is a chronic inflammatory disease with a multifactorial origin that affects the skin. It is characterized by keratinocyte hyperproliferation, which results in erythemato-squamous plaques. Just as the immune system plays a fundamental role in psoriasis physiopathology, the nervous system maintains the inflammatory process through the neuropeptides and neurotransmitters synthesis, as histamine, serotonin, calcitonin gene-related peptide, nerve growth factor, vasoactive intestinal peptide, substance P, adenosine, glucagon-like peptide, somatostatin and pituitary adenylate cyclase polypeptide. In patients with psoriasis, the systemic or in situ expression of these chemical mediators and their receptors are altered, which affects the clinical activity of patients due to its link to the immune system, provoking neurogenic inflammation. It is important to establish the role of the nervous system since it could represent a therapeutic alternative for psoriasis patients. The aim of this review is to offer a detailed review of the current literature about the neuropeptides and neurotransmitters involved in the physiopathology of psoriasis.

Cutaneous afferent innervation of the human foot sole: what can we learn from single-unit recordings?

Cutaneous afferents convey exteroceptive information about the interaction of the body with the environment and proprioceptive information about body position and orientation. Four classes of low-threshold mechanoreceptor afferents innervate the foot sole and transmit feedback that facilitates the conscious and reflexive control of standing balance. Experimental manipulation of cutaneous feedback has been shown to alter the control of gait and standing balance. This has led to a growing interest in the design of intervention strategies that enhance cutaneous feedback and improve postural control. The advent of single-unit microneurography has allowed the firing and receptive field characteristics of foot sole cutaneous afferents to be investigated. In this review, we consolidate the available cutaneous afferent microneurographic recordings from the foot sole and provide an analysis of the firing threshold, and receptive field distribution and density of these cutaneous afferents. This work enhances the understanding of the foot sole as a sensory structure and provides a foundation for the continued development of sensory augmentation insoles and other tactile enhancement interventions.

Stress, symmetry, and psoriasis: possible role of neuropeptides

The role of stress as a triggering factor in the exacerbation of psoriasis and the clinically symmetric distribution of psoriatic plaques suggested a possible role for neuropeptides in the etiopathogenesis of psoriasis. Several observations by other investigators involving substance P suggested to us a possible role for substance P as a modulator of the inflammatory response in psoriasis. A hypothesis for the role of substance P that would account for the temporal onset with stress, the clinical symmetry of lesions, and the histopathologic features of psoriasis is presented.

Free neurovascular flap from the first web of the foot in hand reconstruction

To identify an anatomically reliable and functionally acceptable neurovascular free flap for use in hand reconstruction, 50 fresh cadaver feet were dissected under the operating microscope, with particular attention paid to the anatomy of the first web area. A distal communicating artery was seen in 100% of dissections, allowing either dorsal or plantar donor artery inflow to nourish the entire flap area. Because of the ease of dissection, the first dorsal metatarsal or dorsalis pedis is suggested as the donor artery, and a dorsal branch of the greater saphenous venous system is suggested as the donor vein. The deep peroneal nerve was seen to consistently innervate the first web and, along with the plantar digital nerves, is suggested as an anatomically identifiable donor nerve. Either part of the foot first web may be used alone or together as a free flap. When indicated further dorsal skin may be incorporated into the web flap to expand its application. Two-point discrimination studies of the lateral plantar surface of the great toe in 50 normal individuals showed an average of 11.2 mm. This was significantly better as a potential donor flap than the medial dorsum of the foot where the average was 32 mm. A single case demonstrating the application of this flap in hand reconstruction is presented.