Vasculitic neuropathy in HIV infection : a clinicopathological study.
Vasculitis causing peripheral neuropathy may be the first sign of HIV infection. We report four such cases in whom the onset of peripheral neuropathy led to the detection of HIV infection. Two patients presented with features of mononeuritis multiplex, while the other two had a lumbosacral polyradiculopathy. A prior history of blood transfusion was forthcoming in one of the patients. Sural nerve biopsies in all the four cases and the muscle biopsy in two, histologically showed evidence of vasculitis. Immunohistochemically, the viral antigen was not demonstrable in any of the biopsies, but on electron microscope, virus-like particles were identifiable in the Schwann cell cytoplasm and the perivascular macrophages in one case. To the best of our knowledge, this is the only report that has documented the virus in the Schwann cells as well as the perivascular macrophages lending credence to the fact that these viruses are neurotropic as well as lymphotropic. Immunoglobulin deposits were not demonstrable in any of the cases, suggesting that direct viral invasion may have a role in the pathogenesis of peripheral nerve vasculitis.
Although every part of the neuraxis with the exception of the neuromuscular junction is susceptible to HIV infection, the peripheral nervous system is one of the frequent targets. The incidence of nerve and muscle involvement varies in different studies from 15 to 50%. Of the various peripheral nerve syndromes with infection, vasculitis of the peripheral nerve occurs in
0.3 to 1% of patients. The other forms of HIV related neuropathy include a distal symmetric polyneuropathy (DSPN), inflammatory demyelinating polyneuropathy (IDP), progressive polyradiculopathy and autonomic neuropathy. We describe four cases in which vasculitis in peripheral nerve and/or muscle was the presenting manifestation of HIV infection. It is therefore essential to rule out the association of HIV seropositivity in cases of vasculitic neuropathy before instituting steroids or immunosuppressive therapy.
Case 1 : A 51 year old man presented in August 1996 with slowly evolving low back pain radiating down the posterior aspect of the thigh and leg, which was associated with numbness of both feet of 4 weeks duration. Two weeks later, he noticed weakness involving the proximal as well as distal muscles of both the lower limbs. A short febrile illness preceded the onset of the neurological symptoms for which he had received systemic antibiotics. Although, he was detected to have hyperglycaemia six months earlier, he was not on any hypoglycaemic agents. He was a taxi driver by profession and admitted to high risk behaviour. A neurological examination revealed mild muscle weakness (4/5 MRC grade) of both lower limbs, asymmetric but minimal impairment of touch and pain over both feet including the soles (right side more affected than the left), absent knee and ankle jerks and restricted straight leg raising beyond 70° on both sides. A provisional diagnosis of lumbosacral radiculopathy due to intervertebral disc prolapse was made. Myelogram confirmed a mild disc protrusion between L4 and L5. Following bed rest and analgesics, he reported improvement in the pain but the weakness progressed requiring significant assistance in ambulation. Clinical review in November 1996 revealed marked bilateral amyotrophy of the thigh muscles and occasional fasciculations in the hamstrings (right). The weakness was profound (Grade 0-3/5), asymmetric (right > left) distal as well as proximal and associated with hypotonia and areflexia of both lower limbs. The plantars were not elicitable and there was no objective sensory loss.
Laboratory investigations revealed normal haemogram and biochemical parameters including fasting blood glucose, blood urea, creatinine, serum calcium, and liver function tests were normal. Urine examination for Bence Jones protein and porphyrins was negative. Vasculitis work up that included RA factor, LE cell, ANA and HBs Ag, was negative. The first ESR was 70 mm in first hour (Westergren). Serum VDRL was reactive (1:8) but CSF VDRL was non reactive. Serum was positive for HIV antibodies by ELISA. CSF examination revealed 6 cells (lymphocytes), protein of 150 mg% and sugar of 52 mg%. Electrophysiological studies detected a severe predominantly axonal, motor sensory neuropathy in the lower limbs and a moderately severe motor and mild sensory neuropathy in the upper extremities. A concentric needle EMG of the tibialis anterior showed fibrillations and absent motor unit potentials (MUPs), while the abductor [digiti] minimi was normal. Left sural nerve biopsy was conducted for categorising the type of neuropathy. He received small volume plasma exchanges [eight] times (350-400 ml blood each sitting) and Benzathine Penicillin. Follow up in January 1997 revealed approximately 50% improvement in functional activity and moderate improvement in the MRC grade by atleast two, in all the muscles.
Case 2 : A 50 year old man was evaluated in June 1996 for subacutely evolving sensory motor symptoms in all four limbs of two months duration. Initially, he developed paraesthesia and distal weakness of the right lower limb followed by weakness of the first three [digits] within a few days. Four weeks later, he noticed weakness of the left half of the face followed by weakness and paraesthesia over the left foot. There were no features of involvement of other cranial nerves or sphincter dysfunction. A month preceding the onset of neurological symptoms, he had painful oedema of both feet which remitted within a few days of treatment (details not known). He reported weight loss and anorexia over the past few months and fever with evening rise of temperature since one week. Although he admitted to excessive alcohol consumption for the past twenty years, he denied any substance abuse or high risk behaviour.
Physical examination revealed fever, anaemia, hypertension (150/110 mmHg) and bilateral non tender matted cervical lymphadenopathy. There was moderate enlargement of both liver and spleen. Neurological examination revealed a left facial palsy, weakness (3/5 MRC grade) of median and ulnar innervated muscles of the right hand and the tibial and peroneal innervated muscles in both lower limbs (right slightly more than the left). Mild impairment of pain and touch was present along the right median nerve distribution in the upper limb and in a stocking distribution in the left lower limb. Ankle jerks were absent and plantar response was flexor. Laboratory investigations revealed haemoglobin of 8.3gm%, total leukocyte count-5200/cmm (Polymorphs-84%, lymphocyte-2%, eosinophils-3%, monocyte-1%), platetets-5.8 lacs/cmm, ESR-123 mm/1hr (Westergren) and peripheral smear showed dimorphic anaemia. Biochemical parameters were within normal limits. Total serum protein level was normal (7.9 gm%), however, the albumin fraction was reduced (2.9 gm%). LE cell, RA factor, ANA, and urine for Bence Jones protein were negative. Stool for occult blood was positive. CSF analysis revealed 5 cells/cmm, protein - 24 mg% and sugar - 41 mg%. CSF cytology did not reveal any abnormal/neoplastic cells. Mantoux test was positive (21 mm induration).
The serum was reactive for HIV by ELISA. Ultrasound examination of the abdomen confirmed the presence of hepatosplenomegaly with mild enlargement of the portal vein but there was no evidence of ascitis. Nerve conduction studies revealed a severe, asymmetric sensory motor predominantly axonal neuropathy and concentric needle EMG of the tibialis anterior and abductor pollicis brevis showed features of active denervation. The cervical node biopsy showed histological evidence of active and healed lesions of tuberculosis. The sural nerve was biopsied for diagnosis.
Case 3 : A 43 year old man presented to the neurology services in one of the hospitals in the city, with distal muscle weakness of the left upper limb of 3 months duration, followed by proximal muscle weakness of the right lower limb. He also complained of sensory impairment over the left lower limb. He had herpes zoster involving the ophthalmic branch of the right facial nerve in the past. On examination, he had left sided lower motor neurone facial palsy as well as left sided median, ulnar and femoral nerve palsies. There was wasting of the right sided quadriceps and the knee jerk on the right was not elicitable.
Analysis of the lumbar CSF revealed no abnormality. An electroneuromyogram showed features suggestive of sensory neuropathy involving the left median and ulnar as well as the right sural nerve in addition to motor axonopathy of the left median nerve. Routine haematological investigations showed total leukocyte count of 7200/cmm (67% polymorphs, 31% lymphocytes and 2% eosinophils), ESR - 86mm /1hour (Westergren). Serological tests for rheumatoid factor and VDRL were negative while HIV was positive. The chest X-ray was normal. The sural nerve and quadriceps muscle were biopsied and referred to this institute for histological evaluation and diagnosis.
Case 4 : A 65 year old lady sought the attention of a neurologist in south India for progressive weakness of all four limbs for the last two months. There was history of having received blood transfusion for anaemia in the past. She was not a diabetic or hypertensive. Examination revealed an anaemic, malnourished lady with features of mild dementia. Neurological examination revealed flaccid quadriparesis. There was predominant proximal muscle weakness. The deep tendon reflexes were preserved. Position sense in the lower limbs was impaired. There was no evidence of nerve thickening. Laboratory investigations revealed haemoglobin 10gm%, total leukocyte count - 1800/cmm and ESR110 mm in first 1 hour (Westergren). The liver function tests were slightly deranged, SGOT being
180 and SGPT 56 U/L, alkaline phosphatase - 485 U/L and creatinine phosphokinase - 2624U/L. The blood sample tested positive for HIV-1 by western blot. The sural nerve and quadriceps muscle were biopsied and referred to this institute for histologic evaluation.
The sural nerve was biopsied in all four cases while the quadriceps muscle was also obtained in 2 cases (Case 3 and 4). The nerves were fixed in formalin and embedded in paraffin. 5µthick transverse and longitudinal sections were stained with Haematoxylin and Eosin, Masson's trichrome for stromal component, Kulchitsky Pal for myelin and Bodian silver to highlight the axons. Immunohistochemical staining was also performed on paraffin sections of the nerves using monoclonal antibodies directed against phosphorylated epitope of M and H peptides of neurofilaments (SMI - 31, 1:1000), cytomegalovirus (DAKO, 1:50), p24 antigen of HIV (DAKO, 1:10) and polyclonal antihuman immunoglobulin (DAKO,1:50) by immunoperoxidase method employing DAB/H2O2 as chromogen. Portions of the nerves (cases 1 and 3) were transferred to glutaraldehyde, processed for araldite embedding and ultrathin sections were screened under JEOL 100CX electron microscope at 60 Kv. The muscle biopsies received from outstation were formalin fixed and paraffin embedded. Transverse and longitudinal sections were stained with H&E as well as Masson's trichrome stains for delineating the stromal component.
Histologically, the sural nerves from all four cases displayed a spectrum of changes varying in severity. The fascicular architecture of the nerves was well preserved but within each fascicle, there was a reduction in myelinated fibre density that ranged from mild (case 3) to moderate (cases 1 and 4) to marked (case 2) with replacement by endoneurial collagen. The common finding in all four biopsies was the striking vasculitis involving preferentially the epineurial vessels. Both medium and small sized epineurial arteries, arterioles and venules showed circumferential, inflammatory infiltrate of varying density comprising of lymphocytes, plasma cells and macrophages infiltrating the wall [Figure. 1a] and spilling into the surrounding epineurium. Some of the vessels showed transmural infiltration with luminal compromise [Figure. 1b]. In others, the epineurium showed a proliferation of small thin walled capillaries, a finding that suggests the presence of remote vasculitis with the resultant ischaemia inducing a neovascularisation. In cases 2 and 4, few medium sized muscular arteries revealed subintimal fibrous thickening, with thrombosis and recanalisation of lumina, fragmentation of the internal elastic lamina and irregular narrowing of the lumen providing tell tale evidence of long standing pathology. Only one of the cases (case 4) showed acute changes in the form of fibrinoid necrosis of the small sized muscular artery, transmural infiltration by polymorphs admixed with karyorrhectic debris. The endoneurium was oedematous with infiltration of the fascicle by a few inflammatory cells. In case 3, only a perivasculitis constituted by mild lymphoplasmacytic cuffing of the small epineurial arterioles and venules was seen. In all the four cases, the endoneurial vessels were either totally spared or showed a sparse sprinkling of lymphocytes in the adventitia, and the walls were thickened and hyalinised (possibly age related). The lining endothelium of the arterioles and venules on the endoneurium in all the cases was prominent, a finding that signifies an ongoing immune mediated pathology.
The degree of myelinated fiber loss delineated by the Kulchitsky pal stain was concordant with the extent of inflammatory vascular damage and ranged from a mild, patchy, non uniform loss (case 1, [Figure. 2a] to an almost total wipe out of the fibres (case 2, [Figure.2b]. Both small and large diameter fibres were involved but the former to a much greater extent with only large diameter fibres remaining in a few fascicles. Active disintegration of myelin, thinly myelinated fibres and sprouting were also evident. Axonal damage far exceeding the degree of myelin loss was demonstrable in all cases in keeping with the vasculitic pathology. Axonal swelling, disintegration and loss was well delineated by immunostaining using antibodies to neurofilament (SMI 31). (case 1, [Figure.3]. Immunostaining of the nerve biopsies failed to reveal CMV or HIV antigens (p24) in the inflammatory cells, schwann cells, vascular endothelium or medial smooth muscle cells. Immunoglobulin deposits were also not detectable on the vessel walls. The muscle biopsies showed well preserved fascicular architecture. Within the fascicles however, there was a marked variation in fibre size with many interspersed angulated fibres indicative of severe degree of neurogenic atrophy. The epimyseal vessels included in the biopsy showed florid vasculitis with mononuclear inflammatory cell infiltration in both the cases (cases 3 and 4). There was no increase in collagen demonstrable on Masson trichrome stain.
Electron microscopic examination of the nerve biopsies (cases 1 and 3) revealed significant reduction in the myelinated fiber density. Many actively disintegrating fibres with myelin degradation products within the Schwann cell cytoplasm were seen. Few of the axons showed a mild increase in neurofilaments within the axoplasm. Within the schwann cell cytoplasm [Figure.4], and the perivascular macrophages, many virus - like particles ranging in size from 100 to 200nm with a central or eccentric hypendensity resembling mature and immature HIV virions were found dispersed within the cytoplasm in case 1. Occasional virions were seen budding from the cytoplasmic membrane. Tubuloreticular inclusions commonly found in cases of HIV infection, were not seen within the endothelial cells.
All the four cases demonstrated evidence of vasculitis of the vasa nervosum on histology. Electron microscopically, virus -like particles were demonstrable within the schwann cell cytoplasm and perivascular macrophages in one case. However, immunohistochemically, HIV antigen was not detectable probably due to the low viral density and antigen load, which is in keeping with most studies in literature.,,
Vasculitis of the peripheral nerve can occur either as an isolated process or, more commonly as a manifestation of a systemic disorder. In Indian literature, the reported incidence of vasculitic neuropathy varies from 5.3% to 13.8% of all types of biopsy proven neuropathies. In HIV/AIDS, vasculitis of the peripheral nerve may be the first sign of HIV infection as was seen in all four of our cases. To the best of our knowledge, there have been no other reports of HIV associated vasculitic neuropathy in Indian literature so far. While it is an uncommon complication of HIV infection, it occurs in 0.1 to 3% of patients with AIDS related complex (ARC) or AIDS. Its occurrence has been noted even in asymptomatic seropositive patients. Le Faucheur et al studying 100 patients with HIV associated peripheral neuropathy found that the CD4 counts in patients with mononeuritis multiplex were lower (125/ml) than those with IDP (194/ml) and higher than patients with DSPN (108/ml in mild and 66/ml in severe). In most patients, the vasculitis is not systemic. Pathologically, studies show marked involvement of the microcirculation with inflammation and fibrinoid necrosis of arteries smaller than those that are typically affected in polyarteritis nodosa. Inflammatory cells have been immunologically characterised as CD8 + T cells and macrophages. This form of vasculitis was seen in all the four cases described in this report though we have not carried out phenotypic characterisation of the mononuclear inflammatory cells in these cases. A milder form of vasculitis in the form of perivascular cuffing by inflammatory cells without vascular necrosis or fibrosis was described by Lipkin et al.
This followed a benign course with spontaneous resolution in 2 weeks to 4 months. Vasculitis associated with CMV is seen in the later stages of HIV infection and is distinct both clinically and histopathologically by its rapid progression and involvement of endoneurial vessels, in the form of narcotising vasculitis with polymorph infiltration. The CD4 counts are usually less than 50/ml. CMV inclusions have been seen in the endothelial as well as inflammatory cells. CMV antigen was not demonstrable by immunohisto-chemistry in any of our cases.
The other forms of peripheral nerve involvement in HIV infection include DSPN which is the most common form of peripheral neuropathy in AIDS. While clinical and electophysiological abnormalities are detected in upto 35% of patients, pathological changes have been found in all patients dying of AIDS. Histologically, most workers describe axonal loss with little inflammation. Simpson et at studying 165 cases noted that the frequency of DSPN varied inversely with CD4 counts below 200/ml. Rance et al demonstrated degeneration of the gracile tract in the spinal cord and proposed that DSPN is a dying back neuropathy secondary to ganglionitis/gracile tract degeneration. A direct effect by the virus was also considered following isolation of the virus from the peripheral nerve in a single case and demonstration of virus like particles in the axoplasm of the nerve fibre in another case.
IDP occurs early in the course of HIV infection and may be the presenting disorder at the time of seroconversion. Except for the presence of CSF pleocytosis, the clinical manifestations, course and response to treatment are identical to that seen in HIV seronegative individuals. The pathogenesis too, may be similar, as circulating auto-antibodies reactive with peripheral nerve components have been reported, and the patients respond to different modes of immunomodulation such as plasmapheresis, corticosteroid and intravenous immunoglobulins. HIV has not been localised in the endoneurial cells in these patients but immune deposits have been seen in nerve biopsies. IDP can also occur later on at the stage of ARC and AIDS. IDP when associated with low CD4 counts is usually secondary to CMV infection.
The pathogenesis of vasculitis in HIV is largely speculative. The finding of immunoglobulin deposits and complement as well as immune complexes on the vessel wall in some studies, suggest an immune mediated disorder.,, Circulating immune complexes directed against the HIV virus itself or induced by the opportunistic infections are commonly observed in patients with AIDS. These complexes if deposited on vascular walls could conceivably initiate vascular injury, as in polyarteritis nodosa. A direct role by viral invasion of the peripheral nerve was also considered following isolation of the virus from peripheral nerve homogenates., But the viral antigens have never been detected in the peripheral nerve either by PCR or by immunohistochemistry even in the nerve from which the virus was isolated.,, Only Gherardi et al reported evidence of HIV viral replication in perivascular macrophages in two patients with narcotising vasculitis and AIDS by in situ hybridisation, suggesting that these could be local sites for replication of the virus. Under electron microscope, we observed virus like particles in the Schwann cells and perivascular macrophages in one of two cases examined. There has been only two other reports thus far documenting 'HIV -virus like' particles in the peripheral nerve, localised to the axoplasm in one patient with DSPN and perivascular macrophages surrounding small endoneurial vessels in a patient with narcotising vasculitis. Other factors implicated include the neurotoxic effects of circulating gp120, local release of tumour necrosis factor ? and other T-cell and macrophage related cytokines. In fact, tumour necrosis factor is a known to enhance HIV replication in vitro and also cause tissue damage in peripheral nerved. The pathogenesis of vasculitis in HIV/AIDS is therefore possibly a complex interaction between immune complexes, cytokines that induce the macrophages to enhance HIV replication and initiate the pathway of vascular injury resulting in vasculitis. The axonopathy could result from a direct toxic effect of the virus itself, lymphokine mediated injury or vasculitis related ischaemia. The axonal damage with limited reparative process may lead to progressive neuropathy with limited response to various therapies.
Although the reported incidence of HIV seropositivity in patients with systemic vasculitis is not high, the importance of ascertaining the HIV status in all patients presenting with mononeuritis multiplex is underscored by these four cases where the onset of peripheral neuropathy led to the recognition of HIV infection. The standard treatment for vasculitis may further depress immunity in HIV infected patients, who are already at risk of developing opportunistic infections, because of their altered immune state, use of corticosteroids and other immunosuppresants. Intravenous immunoglobulins may be the preferred mode of treatment in HIV seropositive patients with vasculitis.