Historically, lumbar sympathectomy was primarily done on patients with lower leg blood circulation problems and neuralgia. Later on, some patients with plantar (feet) hyperhidrosis saw good results in having their feet sweating stop after a lumbar sympathectomy. However, side effects such as retrograde ejaculation and general pain led to most surgeons around the world not recommending the procedure. At the time, L-2 was destroyed (by being cut or cauterized or resected).
Since the mid-2000s, lumbar sympathectomy has witnessed a resurgence in popularity. Just like with ETS surgery, clamping replaced cutting or cauterizing or resection (of the lumbar chain instead of the thoracic chain in this case), and clamping of L-3 or L-4 instead of L-2 became the treatment of choice for feet sweating ELS surgery (for hand sweating, ETS surgeons switched from T-2 to T-3 and/or T-4).
The resurgence in lumbar sympathectomy started in Brazil and Europe (specifically, Austria and France). In the US, only one surgeon currently performs lumbar sympathectomies with any kind of regularity.
September 2010 Austrian and Brazilian doctors' summary of 130 lumbar sympathectomy patients (mostly female).
December 2009 Austrian doctors' summary of 90 lumbar sympathectomy patients.
Dr. Reisfeld's page on lumbar sympathectomy. He is the only surgeon in the US with any significant experience in this procedure as of 2010.
Dr. Tarfusser's page on lumbar sympathectomy.
Korean experiences with chemical lumbar sympathectomy block (CLSB) for feet sweating.
UPDATE January 17 2012: At the end of December 2011, someone e-mailed me and wanted to urgently talk on the phone about Hidrex and Idromed (and also advise me about lumbar sympathectomy that he already had). I called that person, and he told me that he had lumbar sympathectomy 1.5 years ago, and the results were excellent for 1.5 years with no side effects. However, recently, the sweating had returned to almost original levels in his right foot, and 10 percent of original levels in his left foot. This person got operated on by Dr. Reisfeld, but was not keen to pay around $13k a second time for a repeat procedure and was thus curious about iontophoresis. If he calls or e-mails me again, I will update this interesting case. This person's health insurance provided almost no reimbursement for his surgery. So if you do end up going to Dr. Reisfeld, I would recommend asking for a free or highly discounted procedure in case of symptom recurrence within a few years.
The above study results sound promising, although most of the patients surveyed got the surgery done recently and cannot discuss long-term satisfaction rates. Moreover, there are some cases of significant side effects, including compensatory sweating, neuralgia, and one case of the dreaded retrograde ejaculation problem in one of the studies. Dr. Reisfeld's site lists other issues that can arise, including potential recurrence (rates of which are not measurable as of 2010 since the T-3 and T-4 level ELS procedures are quite recent), a temporary increase in hand sweating for some patients, and a potential need to do a more intensive open sympathectomy instead of an endoscopic one in a few tough cases.
My already significant feet sweating increased substantially after my ETS surgery that successfully cured my hand sweating, but I prefer to stick with Idromed (or nothing when busy/travelling) for now rather than undergo a lumbar sympathectomy. Because my feet do not sweat when I am asleep and because I can wear socks for most of the rest of the day (in case the feet start dripping -- which is usually half my waking time), I can cope with the problem a lot better than I could with the excessive sweaty hands problem. I would also most definitely rather have sweaty feet than risk some kind of sexual dysfunction or lower feet pain side effect in the long run. I feel like there will be a better solution within the next decade, just like the laser sweat ablation and miraDry procedures for curing armpit sweating, that have become popular since 2009.