Central neuropathic itch from spinal-cord cavernous hemangioma: a human case, a possible animal model, and hypotheses about pathogenesis

Abstract

Cavernous hemangiomas (cavernomas) of the spinal cord are rare congenital malformations that comprise less than 5% of all intramedullary lesions. Despite this rarity, we describe the third case of central neuropathic itch associated with intramedullary cavernoma. Since fewer than 10 cases of central spinal itch from all causes have been published, this concurrence suggests the possibility of a specific association. A middle-aged man developed chronic disabling neuropathic itch and pain affecting his left shoulder and arm after frank hemorrhage of a midcervical cavernoma. We hypothesize that the relatively rostro-dorsal location of his lesion increased its likelihood of causing itch as well as pain. The microscopic pathology of cavernomas, specifically their gliotic rim containing hemosiderin-laden phagocytes, fosters ectopic firing of nearby neurons and makes cranial cavernomas highly epileptogenic. We hypothesize that these pathological features predispose cavernomas to cause central itch if they are located near, but spare, the central itch projection neurons in lamina I of the dorsal horn. Quisqualate injections into the deeper layers (neck) of the dorsal horns of rats produce pathologically similar lesions. Such rats develop unilateral dermatomal hyperalgesia and self-injurious scratching and biting (autotomy). Although this pathological grooming is currently interpreted as a response to chronic pain, we propose that it more likely models scratching provoked by central neuropathic itch, as seen in our patient and others. Study of quisqualate-injected rats may provide leads towards new treatments for neuropathic itch.

Sensory function after cavernous haemangioma: a case report of thermal hypersensitivity at and below an incomplete spinal cord injury

“…To summarize, although dysaesthesia, itch and pain have been previously described following IH, 2 here we confirm the diagnosis of NP symptoms and signs at and below spinal haemorrhage using a graded sensory testing regime. 3 The development of dysaesthesia and Figure 3 Real-time eVAS intensity ratings (42 ¼ painful) to tonic (10 s) thermal stimuli applied at and below the IH.…”

“…1 Furthermore, a recent clinical case of IH documented the presence of itch and dysaesthesia, although the presence of specific pain types following haemorrhage of a midcervical cavernoma was not fully explored. 2 As such a definitive diagnosis of NP with a comprehensive graded sensory testing regime 3 is required to clearly demonstrate the role of IH in sensory dysfunction, including description of the dermatomal distribution of pain symptoms and signs, corroborated with specific magnetic resonance imaging (MRI) imaging for haemosiderin.…”

The clinical outcomes after complete surgical resection of intramedullary cavernous angiomas: changes in motor and sensory symptoms

“…The remaining gliotic rim could be the cause of the low recovery rate because it may induce adjacent neural firing after surgery. 9 However, we believe that the removal of the gliotic rim could cause postoperative neurological deficits by the injuring the normal cord.…”

“…All patients suffered from progressive clinical symptoms and signs. We identified the three patterns of presentation published by Zevgaridis et al 9 Four patients (A, 29%) showed multiple episodes of discrete neurological deterioration with varying degrees of recovery between acute attacks. Seven patients (B, 50%) showed slow progression of neurological deterioration and three patients (C, 21%) experienced sudden-onset symptoms with rapid decline or gradual worsening.…”

Intractable Pruritus After Traumatic Spinal Cord Injury

“…The distinguishing factor between chronic pruritus and pain is the behavior that the two perceptions evoke. Pain triggers withdrawal, whereas pruritus triggers both reflex and conscious mechanical stimulation (eg, scratching) of the affected area (2).…”