Although the entire neuraxis is susceptible, the most common neurologic complications of HIV-1 involve the peripheral nervous system. In addition to painful sensory neuropathy, other types of neuropathy seen are AIDP, CIDP, autonomic neuropathy, polyradiculopathy, mononeuropathies, mononeuritis multiplex, cranial neuropathies, and ALS-like motor neuropathy. With the advent of highly active antiretroviral therapy (HAART), the incidence of most neurologic complications has declined; however, the incidence of peripheral neuropathy has increased, with distal sensory polyneuropathy and antiretroviral toxic neuropathy being the most frequently reported forms. Abnormalities in calcium/calmodulin-dependent protein kinase (CAMKK2) gene predispose HIV-associated distal sensory peripheral neuropathy. Volumetric assessment of brain has revealed that atrophied posterior cingulate cortex is associated with neuropathic pain. Neuropathic pain is a disabling complication for which no satisfactory treatment is currently available. A Cochrane review failed to demonstrate efficacy of pregabalin in HIV neuropathy. Substantial reduction in the prevalence of distal sensory peripheral neuropathy takes place following combination antiretroviral treatment in treatment-naïve people with HIV. In this update, the author reviews the latest findings on the clinical presentation, management, and pathogenesis of these and other peripheral nerve complications of HIV-1 infection.
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• Peripheral nerve complications are one the most common neurologic complication of HIV infection.
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• HIV associated neuropathy is either because of the disease itself or to toxicity of antiretroviral therapy.
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• HIV associated neuropathy leads to significant morbidity and significantly affects the daily activities.
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• In addition to painful sensory neuropathy, other types of neuropathy seen are AIDP, CIDP, autonomic neuropathy, polyradiculopathy, mononeuropathies, mononeuritis multiplex, cranial neuropathies, and ALS-like motor neuropathy.
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• Current treatment for disabling neuropathic pain is far from satisfactory.
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• Drugs used for neuropathic pain include gabapentin, lamotrigine, pregabalin, amitriptyline, duloxetine, and high-dose topical capsaicin patches.
Historical note and terminology
Incidence. Neurologic complications of HIV-1 have been reported for over 20 years (27; 143), and it is widely appreciated that the entire neuraxis is susceptible to complications. With the advent of HAART and prolonged survival, the incidence of most neurologic complications has declined; however, the incidence of distal sensory polyneuropathy has increased, with distal sensory polyneuropathy and antiretroviral toxic neuropathy remaining the most frequently reported neurologic manifestations. Other peripheral nerve complications include acute or chronic demyelinating neuropathies, mononeuritis or mononeuritis multiplex, autonomic neuropathy, and polyradiculopathy (23).
In retrospective studies of patients with acquired immune deficiency syndrome, the incidence of peripheral neuropathy syndromes is estimated to be 10% (202; 126). When including patients with electrophysiologic evidence of polyneuropathy who lack clinical symptoms of peripheral neuropathy, the incidence rises to 40% (99; 204). This figure increases to 48% to 100% in pathologic studies (53; 135).
Prospective series reveal an incidence of peripheral neuropathy of 5% to 60%, depending on the disease stage and neuropathy definition (204; 31; 87; 95; 06; 185; 63). A study of 252 patients enrolled in a pre-HAART trial of HIV-infected individuals with memory complaints and CD4 counts less than 300 found a prevalence rate of 20% for asymptomatic neuropathy and 35% for symptomatic neuropathy. The estimated incidence rate of symptomatic distal sensory neuropathy was 36% after 12 months and 52% after 24 months (185). In the age of HAART therapy, the same group found the 1-year incidence of symptomatic distal sensory neuropathy decreased to 21% (186).
In a cross-sectional study from Uganda, among 800 participants (400 HIV- and 400 HIV+), neuropathy was present in 13% of the participants. Neuropathy was more common in HIV+ patients (19% vs. 7%, respectively). Older age significantly increased the risk of neuropathy in patients with HIV infection (184). HIV-infected pediatric patients are also vulnerable for peripheral neuropathy. In rural South Africa, 182 HIV-infected children on antiretroviral therapy were assessed for peripheral neuropathy. Symptoms of neuropathy were present in 48 children (28%), and signs were noted in 25 children (14%). A diagnosis of peripheral neuropathy was confirmed in 42 children (24%). Risk factors were co-trimoxazole prophylaxis and didanosine use (159).
When approaching the diagnosis and management of these complications, it is essential to determine 4 things: (1) the specific localization of the lesion (ie, spinal cord, nerve root, plexus, peripheral nerve, or multiple peripheral nerves); (2) the staging of the HIV infection (determined by the total CD4+ lymphocyte cell count, the total HIV viral load, and the patient’s clinical condition); (3) the patient’s medication regimen; and (4) the presence of concomitant disease processes.