The Digital Nerves and the Nerve Endings in Progressive Obliterative Vascular Disease of the Leg

N states of diminished arterial blood flow I in a limb, alterations in skin sensibility may occur. In some cases there may be spontaneous pain. This is distinct from the claudication which, particularly in the lower limbs, is an almost invariable accompaniment of inadequate circulation and is due to muscle ischaemia. The so-called ‘ischaemic neuritic’ pain is not common. In its more usual form it is described by the sufferer as a burning pain and located immediately below the skin, although a second component may be present in which pain shoots up the limb. It occurs in two main types of case. The first follows an acute arterial block with at first a poor blood flow which is adequate however to preserve the integrity of the skin. The second occurs at the opposite extreme in cases of long standing progressive arterial insufficiency. In both, the skin of the affected limb may atrophy but may return to an almost normal appearance when compared with its allegedly normal fellow. On testing skin sensation there is diminished sensibility to touch and pinprick, though in some cases hyperaesthesia and hyperpathia may develop. The picture is ordinarily labelled ‘ischaemic neuritis’ but short of this, careful inquiry in the majority of patients with arterial block establishes that at some time in their disease there has been a period of paraesthesia, of hypo-aesthesia or hyperaesthesia which has subsequently diminished. In a few cases this period of disturbed sensation progresses until the patient may present primarily with the diagnosis of ‘ischaemic neuritis’. In an investigation of the nerves of the leg in ischaemic neuritis we have had occasion to examine the skin of the foot, particularly that of the great toe, in a number of conditions. This preliminary paper reports the findings in four representative cases: one normal, one presumed normal but later shown to have some changes in the nervous structures, one from a chronic progressive athero-sclerotic obliterative process giving rise to spontaneous pain with the fully developed features of ‘ischaemic neuritis’ and one from an acute ischaemic process of minor degree in which, during the short period of life following an accident, the patient had neither subjective nor objective evidence of loss of sensibility on the skin of the foot and toes. For comparison the digital nerve of the great toe from a child of 3 years is described and figured.