**5.4 Intercapillary distance (ICD)**

It is the distance between apical tips of two capillaries and varies between 96 and 166 μm [8]. Avascular areas are defined as the areas in which two or more

**193**

disorders.

**Figure 3.**

**5.5 Microhemorrhages**

diseases such as scleroderma.

**6.1 Raynaud's phenomenon**

**6. Utility of capillary microscopy in rheumatology**

*Schematic representation of various capillary loop dimensions.*

malities encountered in patients with rheumatological diseases.

*Nailfold Capillaroscopy in Rheumatic Diseases DOI: http://dx.doi.org/10.5772/intechopen.92786*

capillaries are missing as compared to the other areas with low capillary density [9]. Other authors term an ICD of more than 500 μm as avascular areas [8]. These are typically seen in connective tissue diseases and are not associated with nonimmune

These are reddish brown punctate lesions found in the nail bed. These represent early vascular damage and are most prominently visualized in connective tissue

Rheumatologists frequently encounter situations in which patients present with complaints such as arthralgia, Raynaud's, lung disease, etc. However, many of these patients lack the typical clinical features to classify as a definite systemic connective tissue disease such as scleroderma, MCTD, and others. In such scenarios, NFC can serve as a useful modality in differentiating patients with and without connective tissue disease. The common nail abnormalities encountered include dilated loops, microhemorrhages, and capillary dropouts. Here we shall study the NFC abnor-

Raynaud's phenomenon is an exaggerated responsiveness of the vasculature to cold and other stimuli. It can be primary (in absence of an associated disorder) or secondary (associated with a systemic disease such as scleroderma). NFC can serve as a useful tool in distinguishing primary from secondary Raynaud's. Mannarino et al. [10] described three capillaroscopic patterns in patient with

*Nailfold Capillaroscopy in Rheumatic Diseases DOI: http://dx.doi.org/10.5772/intechopen.92786*

*Vascular Biology - Selection of Mechanisms and Clinical Applications*

to the transparent nature of the skin in them.

hemorrhages. The same are discussed in detail below.

derma, mixed connective tissue disease (MCTD), and dermatomyositis.

suboptimal resolution.

thumb are evaluated.

procedure.

analysis [4].

**5. Capillary parameters**

**5.2 Capillary density (CD)**

**5.3 Capillary width**

**5.1 Capillary shape**

used in optimum quantity, and too little or too much of the oil may result in

vi.A series of 4–12 overlapping images are taken in each finger to complete the

ix.Usually the fourth and fifth fingers provide the maximum information due

A normal capillary has a safety pin or inverted U appearance with an arterial and venous limbs. The venous arm is larger than the arterial arm. However, the capillary loops may exhibit morphological variations, such as crossed or meandering loops (with intertwining). Bushy or excessively tortuous capillaries are seen in sclero-

It is the number of capillaries in 1 mm length of the distal row of each finger or toe. A capillary loop is considered to be in the distal row, if the angle between the apex of that capillary loop and the two adjacent capillary loops is more than 90° [5]. Capillary density of more than 9 is usually taken as normal, albeit age-related changes in the parameter [6]. A mean CD for each finger is calculated by analyzing four fields in the same.

Literature has used different parameters while reporting on capillary width. Some studies have reported on the width of the apical loop, arterial limb, and venous limb, while the others have reported on the whole width of capillary loop (**Figure 3**). Here we shall consider the whole width of capillary loop while describing the dimensions. The normal capillary loop diameter ranges from 25 to 50 μm in adults. A capillary width of more than 90 μm is generally taken as an enlarged loop [7]. Uniformly enlarged capillaries are typically seen in SSc, dermatomyositis, and mixed connective tissue disease. The term giant capillary is used to denote a capil-

It is the distance between apical tips of two capillaries and varies between 96 and 166 μm [8]. Avascular areas are defined as the areas in which two or more

lary diameter of more than four times the normal size.

**5.4 Intercapillary distance (ICD)**

x.The parameters evaluated include capillary density, morphology, and

vii.Conventionally the medial four fingers of both the hands excluding the

viii.Fingers which have sustained a recent injury are excluded from the

**192**

**Figure 3.** *Schematic representation of various capillary loop dimensions.*

capillaries are missing as compared to the other areas with low capillary density [9]. Other authors term an ICD of more than 500 μm as avascular areas [8]. These are typically seen in connective tissue diseases and are not associated with nonimmune disorders.
