***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Acute neuritis and persistent pain are the most significant clinical manifestations of herpes zoster and are end points for clinical trials therapy . In an acyclovir and prednisone study , patients were categorized according to pain severity and number of lesions at presentation  . Risk categories were defined according to the magnitude of risk ratios ( RRs ) and a comparison of Kaplan-Meier survival estimates . For acute neuritis and zoster-associated pain , RRs defined rate of resolution . Patients who presented with  severe or incapacitating pain  and a large number of lesions were less likely to achieve resolution of both acute neuritis and zoster-associated pain ( RR , 18.0 ; 95 % confidence interval [ CI ] , 6 . 6 - 48.6 , and RR , 5.3 ; 95 % CI , 4.2 - 17.2 , respectively ) . These analyses identify the subgroups of patients for whom aggressive interventions are most strongly indicated We studied the effects of spinal cord stimulation ( SCS ) on  postherpetic neuralgia ( PHN ) .  Data of 28 patients were prospect ively investigated over a median period of 29 ( quartiles 9–39 ) mo . In addition , four patients with acute herpes zoster ( HZ ) pain were studied simultaneously . After intractable pain for more than 2 yr , long-term pain relief was achieved in 23 ( 82 % ) PHN patients ( median , 70 yr ) during SCS treatment confirmed by a median decrease from 9 to 1 on the visual analog scale ( P < 0.001 ) . In five cases with serious comorbidity , the initial pain alleviation could not be stabilized . Spontaneous improvement was always confirmed or excluded by SCS inactivation tests at quarterly intervals . Eight patients discontinued SCS permanently because of complete pain relief after stimulation periods of 3–66 mo , whereas 2 reestablished SCS because of recrudescence after 2 and 6 mo . Considerable impairments in everyday life , objectified by the pain disability index , were also significantly improved ( P < 0.001 ) . In 4 patients with acute HZ pain  , SCS was promptly effective and after periods of 2.5 ( quartiles 2–3 ) months the pain had subsided . SCS seems to offer a therapeutic option for pharmacological nonresponders Objective : The purpose of this study was to investigate the effects of continuous epidural blockade on  acute zoster-associated pain  , compared with intermittent epidural blocks . Design : The design was a retrospective , nonr and omized study . Setting : The study was conducted at a university hospital in Japan from 1982 through 1992 . Patients : A total of 178 otherwise healthy patients hospitalized with moderate or severe herpes zoster lesions . Interventions : Group A ( n = 66 ) had intermittent epidural blocks using 1 % mepivacaine , 4–6 ml , three to six times daily ; group B ( n = 43 ) were given intermittent epidural blocks and parenteral acyclovir ( 500 mg/day ) or vidara- bine ( 600 mg/day ) for 5 days ; group C ( n = 69 ) were administered a continuous epidural 0.5 % bupivacaine infusion ( 0.3–1.0 ml/h ) for ∼2 weeks and antiviral agents followed by intermittent blocks . Main Outcome Measures : The number of treatment days was used as the outcome measure . Results : The length of treatment was significantly shorter in group C than in groups A or B. For moderate lesions the means ( days ) were 36.2 [ 95 % confidence interval ( CI ) , 31.4–41.7 ) , 45.6 ( 95 % CI , 34.0–61.4 ) , and 26.8 ( 95 % CI , 22.3–32.3 ) for groups A , B , and C , respectively ( p < 0.01 ) . For severe lesions they were 73.3 ( 95 % CI , 55.1–97.7 ) , 81.7 ( 95 % CI , 59.1–113.0 ) , and 44.9 ( 95 % CI , 35.2–57.3 ) for groups A , B , and C , respectively ( p < 0.01 ) . Conclusions : Continuous epidural blockade for patients with acute zoster  can shorten the duration of treatment and may reduce the incidence of postherpetic neuralgia OBJECTIVE To evaluate the relief of acute pain and possible preventive effects on postherpetic neuralgia through the use of an epidural blockade in the acute stage of herpes zoster . DESIGN Prospect i ve , nonr and omized , comparative clinical trial . SETTING A dermatologic clinic in a university hospital . PATIENTS Sixty-five consecutive patients with pain due to acute herpes zoster were treated for a 7-day hospitalization period from July 1 , 1996 , through June 30 , 1997 . INTERVENTION The consecutive patients were divided into 2 groups . Group A consisted of 30 patients who were seen from July 1 , 1996 , through December 31 , 1996 , and who were treated with intravenous acyclovir ( 5 mg/kg ) for 7 days . Group B consisted of 35 patients who were seen from January 1 , 1997 , through June 30 , 1997 , and who were treated with intravenous acyclovir ( 5 mg/kg ) and an epidural blockade for 7 days . The changes in the intensity of pain and the total duration of pain in both groups were assessed for 12 to 18 months . MAIN OUTCOME MEASURES The number of days required for relief of pain and the total duration of pain . RESULTS The mean + /- SD number of days required for relief of pain , which was rated on a scale of 100 ( worst pain ) to 0 ( no pain ) , was significantly fewer in group B than in group A : it took 2.6 + /- 1.1 days to go from 100 to 50 on the relief-of-pain scale in group B , but 3.8 + /- 1.1 days in group A ( P = .03 ) , and 12.5 + /- 6.4 days to go from 100 to 10 in group B , but 20.1 + /- 14.6 days in group A ( P = .04 ) . The duration of late residual pain was significantly shorter in group B ( 5.9 + /- 5.8 days ) than in group A ( 11.9 + /- 7.5 days ) ( P = .03 ) . The total duration of pain was also significantly shorter in group B ( 18.5 + /- 9.3 days ) than in group A ( 31.6 + /- 17.6 days ) ( P = .04 ) . CONCLUSIONS We believe that an epidural blockade combined with an antiviral agent is a very effective treatment modality for the pain of acute herpes zoster , and we recommend its use for the prevention of postherpetic neuralgia , with a view to shortening the total duration of pain , especially late residual pain Background : Treatment of herpes zoster ( HZ ) includes the use of acyclovir with or without steroids . An alternative therapy is the epidural administration of local anesthetics with or without steroids . This trial compared the efficacy of these two treatment regimens in the prevention of  post‐herpetic neuralgia ( PHN ) Seventy-two patients older than 60 years of age who received a diagnosis of herpes zoster ( HZ ) were entered into a r and omized , double-blind , placebo-controlled trial of daily amitriptyline 25 mg . Treatment with either amitriptyline or placebo continued for 90 days after diagnosis . Pain prevalence at 6 months was the primary outcome . Results showed that early treatment with low-dose amitriptyline  reduced pain prevalence by more than one-half ( p < 0.05 ; odds ratio , 2.9:1 ) This finding makes a strong case for the pre-emptive administration of amitriptyline , in combination with an antiviral drug , to elderly patients with acute herpes zoster A ntiviral drugs decrease the pain and enhance the resolution of acute herpes zoster lesions in immunocompetent patients ( l-6 ) . However , the effect of antiviral therapy on postherpetic neuralgia ( PHN ) remains controversial . Whereas some studies reported a lower incidence of prolonged pain with antiviral therapy ( 4 ) , others found no benefit with respect to prolonged pain ( 5 ) . In an attempt to improve patient comfort and long-term outcome with respect to PHN , combinations of different drugs have also been evaluated ( 5 - 7 ) . Anecdotal reports have suggested that electroacupuncture may be helpful in the management of herpes-related pain ( 8,9 ) . Clinical experience with a novel form of electroanalgesia known as percutaneous electrical nerve stimulation ( PENS ) in the treatment of patients with acute herpes zoster suggested that it is effective in decreasing herpes-related pain and is associated with rapid resolution of the cutaneous lesions ( Craig WF , Taylor SM , Fort Worth Center for Pain Management , personal communication , 1997 ) . Therefore , we design ed this clinical study to compare PENS therapy with a st and ard antiviral regimen with respect to the severity of the associated pain , impact on the patient ’s physical activity and quality of sleep , resolution of the herpes lesions , and incidence and severity of PHN 
    Output:
    
In general , the review s support short-term benefit of antiviral drugs , but note limited evidence for a reduction in the incidence of PHN .
Famciclovir and valaciclovir , however , were shown to reduce the duration of PHN .
Oral steroids reduced the severity of acute HZ pain , but had no effect on the incidence , severity , or duration of PHN .