Physiology in Dermatology PDF

PHYSIOTHERAPY IN DERMATOLOGY VICTORIA MASSALHA  LEARNING OBJECTIVES Gain knowledge and understanding of: The pathological changes which occur during dermatological disease or as a result of burns The common congenital deformities which require surgical intervention T...

PHYSIOTHERAPY IN DERMATOLOGY VICTORIA MASSALHA  LEARNING OBJECTIVES Gain knowledge and understanding of: The pathological changes which occur during dermatological disease or as a result of burns The common congenital deformities which require surgical intervention The medical, surgical and physiotherapeutic management of patients suffering from disease, deformity or burns The physical and psychological aspects of patients suffering from dermatological conditions, congenital deformities and burns  THE SKIN STRUCTURE AND FUNCTION  Anatomy Most extensive organ system including appendages (adnexa): hair, nails, glands (sweat - eccrine and apocrine; and sebaceous), specialized nerve receptors (changes in internal or external environment) such as touch, cold, heat, pain, and pressure Weighs ≈ 2.72kgs / six pounds Functions Protective shield against injury (also warning device), pathogens and water loss Temperature regulation Excretion through perspiration Pigmentary protection against UV light Production of oestrogen and vitamin D Storage of body fat Non-verbal communication Sense of Touch In babies, stimulus for brain development Characteristics Varies throughout body in thickness, colour and texture More hair follicles on head vs. none on soles of feet Soles of the feet and palms of the hands have much thicker layers  STRUCTURE Three layers performing specific functions EPIDERMIS DERMIS SUBCUTIS  Epidermis This is the thin outer layer (5 sub-layers) Stratum basale Stratum spinosum Stratum granulosum Stratum lucidum Stratum corneum Thick skin epidermis has all five strata (1.5mm in palms and soles) Thinner epidermal areas such as eyelids (0.10mm) have three or four of the five strata (never the stratum lucidum)  Layers of the Epidermis Stratum basale (deepest layer) Single layer of columnar or cuboidal cells which rest on the basal membrane separating dermis and epidermis Basal cells divide continuously to form keratinocytes replacing those shed at surface Only the deepest of these cells receive nourishment from dermis Cells are sloughed off on reaching surface (desquamation) Contains melanocytes, which produce melanin (pigment responsible for the colour of skin) Stratum spinosum (interlocking cells that support the skin) Contains langerhans cells (dendritic cells also found in lymph nodes containing Birbeck granules - cytoplasmic rod-shaped organelles) N.B. not to be confused with giant L. cells found in conditions such as leprosy and TB (formed by the fusion of macrophages and contain nuclei arranged in a circle or horse shoe) or Islets of Langerhans found in pancreas Stratum granulosum (thin middle layer) Keratinocytes (squamous cells, primary cell type of epidermis) Keratinization (production of keratin) is initiated in this layer Stratum lucidum This thick layer appears only in frequently used areas such as palms of the hands and soles of the feet (protects against UV light) Stratum corneum (fifth, outermost layer) aka the horny layer - continually shedding dead cells containing keratin (protein) Millions of dead cells are shed daily - new epidermis / 35–45dys Keratin acts as a barrier; keeps skin elastic and protects underlying cells from drying out Dermis Middle layer – true skin Major parts: collagen (strength), reticular fibres (support) and elastin (flexibility) Two layers: papillary (spongy / loose CT) and reticular (tough / dense CT) Layers are closely associated and difficult to differentiate Papillary layer Lies directly beneath the epidermis and connects to it via papillae (finger-like projections) Some papillae contain capillaries that nourish the epidermis Others contain Meissner's corpuscles, mechanoreceptors (sensitivity to light touch, lowest threshold) The double row of papillae in finger pads produces the ridged fingerprints on fingertips Merkel cells (touch receptors) clustered at epidermal ridges Similar ridged patterns on palms of the hands and soles of the feet keep skin from tearing and aid in gripping objects Merkel cells Reticular layer Contains collagen fibers that form a strong elastic network Network forms a pattern called cleavage (Langer's) lines. Surgical incisions usually made parallel to these lines (faster healing and less scarring) Also contains Pacinian corpuscles (sensory receptors that respond to transient pressure e.g. rough surfaces and vibration), sweat glands, lymph vessels, smooth muscle, hair follicles Thick skin Pacinian Corpuscle Subcutis Deepest layer, aka the subcutaneous layer Attaches skin to underlying bone and muscle Consists of loose connective tissue and elastin, main cell types: fibroblasts, macrophages and adipocytes Blood vessels (superficial and deep)  Arteriovenous anastomoses to bypass capillaries and regulate body temperature Arteriovenous anastomosis Also contains Peripheral nerves Adipose layer (50% of body’s fat) serves as padding and insulation for the body conserving heat Protects internal organs from injury by acting as a "shock absorber"  Dermatology clinics Skin diseases are on the rise possibly due to changing social and environmental factors Common dermatologic conditions: Psoriasis, eczema, acne, polymorphic light eruption, pigmentary disorders e.g. vitiligo (aka leukoderma) – loss of skin pigment, skin tumours and malignancy e.g. Mycosis fungoides (an unusual form of skin malignancy), alopecia areata (a form of hair loss), and leprosy  Opportunistic Dermatology  Exposure to many dermatological conditions can be increased during other placements  A broad spectrum of skin diseases may present primarily or as a secondary feature  General medicine and general surgical rotations give opportunities to observe the characteristic cutaneous manifestations of diseases which are predominantly systemic e.g. generalized itching due to renal disease  PHOTOTHERAPY Ultraviolet light treatment is given by experienced dermatology physiotherapists Effective tool in treating several conditions The treatment is carefully measured and controlled Treatments are usually two or three times weekly for six weeks Types of treatment: Short wave ultraviolet light (UVB) A mixture of long and short wave ultraviolet light (UVA & UVB) PUVA. This is long wave ultraviolet light with psoralens (a plant extract which sensitizes the skin to ultraviolet light)  Approach to Diagnosing Dermatologic Disease  History of presentation  Morphology  Differential  Directed Medical History & Examination  Diagnostic Testing  Dermatologist  Morphology 1  Language for describing / characterizing & clinically diagnosing dermatologic disease  Lesions  Any single area of altered skin  Solitary or Multiple  Rash or eruption  A widespread eruption of lesions  Color (erythematous, purpuric, violaceous..) Purpuric – (Latin: purpura - "purple") - red or purple discolorations on the skin that do not blanch on applying pressure Violaceous – violet or bluish purple  Morphology 2 Scaling or Hyperkeratosis  Visible increase in dead surface cells (stratum corneum)  Fissures & Cracks  Morphology 3 Lichenification  Palpably thickened skin with increased skin markings caused by chronic rubbing  Morphology 4  Crusting - when plasma exudes through an eroded epidermis, may be  Yellow-brown rough surface build up OR  Red / purple / black if bloody or haemorrhagic OR  Golden yellow or honey coloured  Morphology 4 Crust  Erythematous, scaling & papular eruption  Eroded, weeping  Serous (yellow-brown) + haemo-serous & purulent PLUS Honey colored exudate and crusting Diagnosis: Impetiginized (bacterially infected) Subacute Eczema  Impetiginized Eczema  Staphylococcus aureus or Streptococcus pyogenes usually responsible  Nephritogenic strains of strep can cause acute glomerulonephritis and infect the skin rather than throat  Morphology 5  Cutaneous Reaction Patterns include  Eczematous = Dermatitic (atopic dermatitis, allergic or irritant contact dermatitis, venous eczema, asteatotic [dry skin or winter] eczema)  Urticarial (= wheal or hives) (bug [infection], drug, allergy, pseudoallergic, autoimmune…)  Exanthematic = wide spread rash or skin eruption associated with a systemic infection (drug eruptions & autoimmune disorders often mimic infective exanthems)  Describing Skin Lesions Carefully describe ALL skin lesions Indicate the distribution of lesions (where these are on the body) Indicate configuration of lesions (shape and grouping) Indicate the colour of lesions