Hamstring Syndrome of Tethered Sciatic Nerve – Newer Entity With Surgical Treatment

This syndrome comprises of pain in the gluteal region radiating down thigh to the posterior knee popliteal fossa. It is associated with hamstring weakness. A series of 43 cases were found in athletes and surgically rectified. This resulted in a 75% satisfaction rate.

Am J Sports Med. 2008 Sep 25. [Epub ahead of print] Surgical Release for Proximal Hamstring Syndrome. Young IJ, van Riet RP, Bell SN.
abstract

• Syndrome originally defined in 1988
• Sciatic nerve becomes tethered by a fibrotic band to proximal hamstring near buttock
• On average subjects had about 5 previous hamstring tears.
• Football players comprised a sizable group of the athletes
• Pain occurs with running
• Tenderness is by ischial tuberosity (seat bone) – this differentiates it from hamstring tears which are usually further down and palpable.
• Hamstring weakness tested with knee in 30 degrees flexion. “Examiner pulls down with one hand behind the heel while the patient resists and attempts to maintain position or flex beyond 30°, and the examiner’s other hand is placed on the belly of the hamstring to assess the quality of the muscular contraction”
• piriformis syndrome, sciatica, and neuropathy (nerve damage) are conditions requiring differentiation.

• MRI’s and bone scans mostly normal
• Nerve conduction studies – “abnormalities with slowing of the F or H wave of the sciatic nerve in 18 of 27 (67%).”
• Surgery involved release of sciatic nerve from hamstring
• Following surgery, pain fell from 6.5/10 to 2/10
• 75% were satisfied with results

Addendum:

A similar problem was a tethered sciatic nerve caused by an inflammatory reaction to injury in the buttock called nodular fasciitis – incredibly difficult to diagnose because Imaging is all negative (Something that is becoming more realized in many things).

Spine (Phila Pa 1976). 2010 Oct 1;35(21):E1137-40.
Intractable Sciatica due to Intraneural Nodular Fasciitis Detected by Positron Emission Tomography.
Kakutani K, Doita M, Nishida K, Akisue T, Maeno K, Zhang Z, Yurube T, Kurosaka M.
abstract here

• 37 year old hit buttock hard on bath tub
• Intense pain buttock radiating down leg to lateral calf
• surgical release piriformis did not help
• Imaging all negative
• resorted to PET scan which showed “an abnormal lesion in the sciatic nerve in the posterior compartment of the patient’s left thigh” tethering it.
• Surgical removal of an intraneural nodular fasciitis resolved issue.

Comment – you see what you know and you can’t trust imaging. With recurrent hamstring injuries, this will become a suspect.

Addendum question:

I was in the impression that you needed a previous ”undiagnosed” severe partial or complete proximal hamstring tear to get entrapment of the sciatic?
otherwise, could it be a pyriformis syndrome as a cause or even consequence of repetitive mild hamstring strain? My collegue has bilat hamstring (proximal and myotendinous jct) sprain and bilat pyriformis that seems to have started after.
I would apreciate some input
Thanks!

I am no expert but some things come to mind:

There appear to be different groups involved:

• athletes as per first article in which there is a history of repeated tears
• However nonathletes are represented – one study had people who were “ordinary people sent to the orthopaedic surgeon for consultation. Their athletic activities varied from none to some sports activity as a hobby.”
  as per:
  Entrapment of the proximal sciatic nerve by the hamstring tendons
  Kari SAIKKU, Jarkko VASENIUS, Pekka SAAR
  Acta Orthop. Belg., 2010, 76, 321-324 free article here
  This group appeared just to be blessed with a tight 1 band: their description: “one or more atypical
• tendinous structures along the long head of the biceps femoris adjacent to the sciatic nerve. These tendinous structures could be as tense as a violin string and extend to the thigh over the sciatic nerve. When a finger was placed along the sciatic nerve and the hip was flexed with the knee extended one could feel how these tendinous structures compressed the nerve. In most cases the diameter of these tendinous structures was about 1 cm ; it exceeded 2 cm in two cases.”
• 6/16 (37.5%) cases had bilateral issues

Symptoms in their study included

• tendernesss about ischial tuberosity  – subjects would point to that site as the primary pain area
• active flexion of the hip with the knee extended caused pain in the buttock radiating into the extremity – sounded like a Straight leg raise (SLR) to me…
• Their differentiation from piriformis would be that the patient points to a higher sore area with piriformis. My differentiation would be that it is sore on rectal examine in the greater sciatic notch – and it won’t come out with simple stretch and massage rectally.
• For diagnosing tethered sciatic nerve in hamstring – I would like  transverse sciatic massage not to set it right  – mentioned in another article:
  Diabetic Peripheral Neuropathy – Sciatic Nerve Treatment
  They found grabbing hamstring and push/pulling from side to side while leaving sciatic nerve alone underneath could free up the sciatic nerve (along with SLR) and help diabetic neuropathy cases.  I found mild cases of tethering in certain cases would come free with former stretch and leave the piriformis as a more likely suspect.  However in one case, a third lesion was found – an extruded lumbare disc so go figure.
• I notice when the above article took these patients to surgery they did: “A modified Kocher’s incision dividing the gluteus maximus muscle was used to explore the proximal sciatic
  nerve, with the exception of one case. The patients were lying on the unaffected side. The nerve was explored from the level of the piriformis muscle to below the level of the ischial tuberosity. Possible adhesions were released. Atypical tendinous structures were divided near their origin without loosening the hamstring tendons from the ischial tuberosity. If only adhesions
  between the sciatic nerve and the ischial tuberosity were observed, a subcutaneous tissue transplant was used after releasing the adhesions.” – they weren’t taking any chances of missing anything from piriformis down…
• Got to admit I see much more piriformis than tethered hamstrings so would go for the hamstrings being more important – but I’m no expert…
• Hope this helps

Addendum 2018:

Arthroscopy. 2018 Jan;34(1):122-125. doi: 10.1016/j.arthro.2017.08.260.
Editorial Commentary: Proximal Hamstring Syndrome: Another Pain in the Buttock.
Matsuda DK
https://www.ncbi.nlm.nih.gov/pubmed/29304958

• “Proximal hamstring injuries cause buttock pain and may result in significant weakness and sciatic neuralgia.
• Avulsion ruptures involving 2 or more tendons with >2-cm retraction may benefit from early open surgical repair. More chronic equivalents may benefit from Achilles allograft reconstruction.
• Chronic proximal hamstring syndrome causing posterior thigh and sit pain may occur from less severe, often repetitive injury to the proximal hamstring origin with secondary sciatic neuralgia from local adhesions or scar entrapment. Recalcitrant cases may benefit from surgical intervention, but the most effective procedure (tenotomy, resection of degenerative tissue with tenotomy vs repair, sciatic neurolysis) has not been established.
• The role of endoscopic surgery of the proximal hamstring is evolving, but currently may best be indicated for ischial bursectomy, debridement of degenerative tendon tissue, and/or sciatic neurolysis. Although endoscopic proximal hamstring repair is feasible for treating tears with mild retraction, the role of endoscopic (or open) surgery in repair of acute complete tears with <2-cm retraction or less severe injuries (partial tears or complete tears without retraction) is controversial because most of these injuries may respond to nonoperative management. In this setting, perhaps surgical treatment (open or endoscopic) should be reserved for patients who have failed nonsurgical management.”