Journal ofNeurology, Neurosurgery, and Psychiatry 1992;55:65-67 65

SHORT REPORT J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.55.1.65 on 1 January 1992. Downloaded from

The syndrome after a proximal lesion

Paul Augustijn, Jan Vanneste

Abstract 39 m/s, lowest normal value 40-63 m/s4). The Three patients in whom the first symp- distal motor latencies (DML) were also pro- toms ofthe (TTS) longed in the peroneal nerves (right side emerged after an acute event proximal to 5-9 ms; left side 5-1 ms; normal 4-8 ms4). The but not affecting the are described. HofEnan reflexes elicited from the right soleus These patients suggest that a pre-existing muscles were slightly slowed on both sides. asymptomatic TTS may become mani- with concentric needles fest after a mechanism akin to that de- showed active denervation potentials in the scribed in the "double crush" syndrome. and the extensor digitorum brevis muscle of the right . The time-related association of the vascular event The tarsal tunnel syndrome (TTS), consisting and the neurological symptoms suggested of entrapment of the posterior aggravation of a Sl-, pre-exist- beneath the flexor retinaculum and causing ing , or both. Symptomatic and paraesthesia in the foot, was first treatment was prescribed. He was not seen described by Lam and Keck in 1962.' 2 The again until four years later for increase of the most common causes are local post-traumatic same painful paraesthesia in the right foot. The deformities, constrictive adhesions, local ten- TTS was now considered and seemed probable osynovitis, chronic stasis of posterior tibial in view of a positive sign of Tinel at the medial veins, and other more rare causes.3We know of ankle of the right foot and atrophy of the right no report of TTS emerging after more prox- abductor hallucis muscle. Neurophysiological imally situated tibial nerve involvement. We abnormalities were similar to those found four describe three patients with this condition. years previously, but additional investigations were consistent with the TTS,4 including a slowed sensory nerve conduction velocity of Case reports the right (23 m/s, normal: Patient 1 27-96 m/s); this contrasted with a normal con- A 63 year old man presented at the emergency duction velocity ofthe left medial plantar nerve

department 36 hours after acute embolic (34 m/s). The DML in the tibial nerves were http://jnnp.bmj.com/ occlusion of the right common femoral artery. asymmetrical (right 5-1 ms, left 4 0 ms, normal Clinical examination showed a livid and cold 5-1l1 ms4). Division ofa clearly thickened flexor leg with absent arterial pulsations. Embolec- retinaculum resulted in disappearance of the tomy resulted in restoration of the circulation symptoms, with no recurrence on follow up. but he then complained ofpainful paraesthesia, most pronounced in the calf and the sole of the Patient 2 right foot. He was known to have stage II non- A 57 year old man presented with symptomatic Hodgkin lymphoma, which had been treated subacute obstruction of the left superficial on September 30, 2021 by guest. Protected copyright. with a combination of cyclophosphamide, femoral artery. A popliteal bypass with a ven- adriamycin, vincristine, and prednisone. The ous graft was performed 24 hours later but lymphoproliferative disease was in a stable resulted in pain, paraesthesia, and numbness in condition. Neurological examination showed a the sole of the left foot, which were considered diminished reflex in the right ankle and diffuse as residual symptoms of limb ischaemia. Per- hypaesthesia in both feet. Radiography of the sistence of his complaints led to neurological lumbar spine showed a grade 1/4 L5-S1 spon- examination, which showed a positive Tinel's dylolisthesis, and a radiculogram with sign at the medial and hypalgesia at Department of metrizamide showed minimal compression of the ventro-medial side of the sole of the left , the L5 and SI roots on both sides. St Lucasziekenhuis, foot. Results of nerve conduction studies and were J Tooropstraat 164, Conduction velocities of the nerves electromyography were consistent with the 1061 AE Amsterdam, measured under control of skin temperature, clinical diagnosis of TTS: the DML derived The Netherlands which was kept between 33°-36° C by warming abductor hallucis muscle P Augustijn from the (6-8 ms; J Vanneste up the leg in hot water (also done for the two normal 5-11 ms) was prolonged, which con- other patients). Low normal or slightly dimin- a DML derived from the Correspondence to: trasted with normal Dr Vanneste ished motor nerve conduction velocities were (5-0 ms; normal 5-3 ms). Received 29 October 1990 found for the right (33 m/s) and the left There was also denervation activity in the left and in final revised form nerves 41-65 con- 8 April 1991. (41 m/s) peroneal (normal m/s4) abductor hallucis and a complete sensory Accepted 16 April 1991. and for right and left tibial nerves (40 and duction block of the left medial plantar nerve 66 Augustijn, Vanneste

over the flexor retinaculum. Surgical decom- resulted in "decompensation" ofa pre-existing J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.55.1.65 on 1 January 1992. Downloaded from pression ofthe tibial nerve at the ankle resulted asymptomatic TTS, via a mechanism similar to in complete and persistent improvement. that described by Fullerton in CTS5: she compared normal subjects and patients with Patient 3 CTS and found a greater susceptibility to A 38 year old football player was admitted with ischaemia in patients with CTS, with early a right sided fracture at the distal third of the failure of motor nerve conduction. Later, tibia and fibula. No evidence was detected of a Upton and McComas described a series of second lesion near the medial malleolus. The patients in whom the median or ulnar nerves fracture was treated with repositioning, trac- were compressed at two different sites and tion, and immobilisation. Two weeks later the proposed their so-called "double crush theory" patient experienced increasing pain and numb- to explain that the occurrence of symptoms ness on the medial side of the right foot. was facilitated by a concomitant cervical radi- Neurological signs consisted of impaired plan- culopathy.6 The proximal compression would tar flexion of the third, fourth, and fifth toes, decrease the resistance ofthe nerve to a second, hypalgesia in the sole of the foot, and diffuse more distal entrapment. This would facilitate hypaesthesia in the tibial and peroneal nerves the occurrence of the distal to the fracture. Percussion of the calf at or an compression neuropathy. the site of the fracture elicited paraesthesia in Experimental studies have added further the sole of the foot. Motor nerve conduction arguments to the double crush theory. Shimpo studies showed a normal conduction of the et al tied silk ligatures round the of right tibial nerve to the gastrocnemius muscle guinea pigs to produce permanent nerve con- (DML 3-6 ms; normal 5-3 ms) and a distal striction.7 They found that local plantar nerve conduction block to the abductor hallucis mus- lesions developed in the sole of the foot of the cle. A total conduction block of the medial affected side, possibly due to the pressure from plantar nerve was present on the right side. the floor of the cage. They suggested an Electromyography showed active denervation increased sensitivity to local pressure occurred potentials in the abductor hallucis muscle. A in atrophic nerve fibres distal to the constric- tibial nerve lesion or entrapment at the site of tion. Nemoto et al found that the loss of nerve the fracture was suspected. Surgical explora- function after a double lesion in sciatic nerves tion and neurolysis ofa slightly entrapped tibial of dogs was greater than the sum of the deficits nerve were carried out but did not result in after each separate lesion.8 They concluded neurological improvement. Six months later that proximal compression of a nerve could TTS was considered; this was confirmed by lessen its ability to withstand further compres- clinical re-evaluation and neurophysiological sion more distally. data, which were the same as six months In patients who have suffered severe and previously. At surgical intervention distinct prolonged limb ischaemia one of the mechan- fibrosis ofthe flexor retinaculum and a severely isms leading to a double crush phenomenon compressed and atrophic tibial nerve were might be that axonal anoxia and subsequent found. Neurolysis led to decreased pain and deficient oxidative phosphorylation result in numbness in the sole of the foot. disturbed axoplasm transport, which is closely dependent on oxidative metabolism.9 This

might lead to an increased susceptibility of the http://jnnp.bmj.com/ Discussion distal axon to further ischaemic or compressive Our three patients were characterised by the damage.7 In two of our patients prolonged onset or aggravation of neurological symptoms ischaemia of the leg probably resulted in in one foot after an event in the leg, proximal to ischaemic nerve damage,'0 as has been pre- the tarsal tunnel. Although restoration ofnerve viously described by Welti et al" and Ferguson function was not documented by post- and Liversedge. 2 These authors described operative neurophysiological reassessment, selective peroneal palsies after acute limb TTS seemed most probable in view of the ischaemia, attributing this ischaemic mono- on September 30, 2021 by guest. Protected copyright. persistent improvement after tarsal tunnel neuropathy to an increased susceptibility ofthe decompression in all patients. nerve after a relatively poor blood supply in the In patient 1 aggravation ofthe radiculopathy region of the fibular head. We could trace no or the polyneuropathy after the vascular opera- more reports on TTS emerging after a second tion was suspected. In patient 3 damage or more proximal lesion so further studies are compression ofthe tibial nerve at the site ofthe needed to confirm the theory that some cases of trauma seemed the most probable cause. Con- TTS may be due to a "double lesion neuro- sequently the diagnosis of TTS was consider- pathy", a term that seems more appropriate ably delayed in these two patients. We cannot than "double crush syndrome",11 as in most totally exclude alternative mechanisms ex- cases nerve damage is not due to crushing. plaining the rapid onset of TTS; there may have been prolonged compression ofthe medial We thank Drs H van Duyn and M Laman for ankle during the operation but this was tech- neurophysiological advice. nically improbable. A concomitant traumatic lesion to the ankle in patient 3 was conceivable, but this was neither nor 1 Lam SJS. A tarsal tunnel syndrome. Lancet 1962;ii:1354-5. clinically radiologically 2 Keck C. The tarsal tunnel syndrome. J Bone Joint Surg apparent. The most plausible aetiology is that 1962;44A:180-2. an ischaemic 1 and or traumatic 3 Edwards WG, Lincoln CR, Bassett FH, Goldner JL. The (patients 2) tarsal tunnel syndrome: diagnosis and treatment. JAMA (patient 3) proximal nerve damage may have 1969;207:716-20. The tarsal tunnel syndrome after a proximal lesion 67

4 Oh SJ. Tarsal tunnel syndrome. In: Clinical electromyo- K, Mori Y. An experimental study on the "double crush" J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.55.1.65 on 1 January 1992. Downloaded from graphy: nerve conduction studies. Baltimore: University hypothesis. J Hand Surg 1987;12A:552-9. Park Press, 1984:408-10. 9 Ochs S. Basic properties of axoplasmic transport. In: 5 Fullerton MP. Effect of ischaemia on nerve conduction in . Dyck PJ, Thomas PK, Lambert carpal tunnel syndrome. J Neurol Neurosurg Psychiatry EH, Bunge R, eds. Philadelphia: Saunders, 1984:453-76. 1963;26:385-97. 10 Daube JR, Dyck PJ. Neuropathy due to peripheral vascular 6 Upton ARM, McComas AJ. The double crush in nerve- diseases. In: Peripheral neuropathy. Dyck PJ, Thomas PK, entrapment syndromes. Lancet 1973ii:359-61. Lambert EH, Bunge R, eds. Philadelphia: Saunders, 7 Shimpo T, Gilliatt RW, Kennett RP, Allen PJ. Suscep- 1984;1459-78. tibility to pressure neuropathy distal to a constricting 11 Welti JJ, Melekian B, Reveillaud M. Paralysies peri- ligature in the guinea-pig. J Neurol Neurosurg Psychiatry pheriques ischimiques. Pr Med 1961;69:333-4. 1987;50:1625-32. 12 Ferguson FR, Liversedge LA. Ischaemic lateral popliteal 8 Nemoto K, Matsumoto N, Tazaki K, Horiuchi Y, Uchinishi nerve palsy. Br Med J 1954;2:333-5. http://jnnp.bmj.com/ on September 30, 2021 by guest. Protected copyright.