Journal of Neurology Research, ISSN 1923-2845 print, 1923-2853 online, Open Access
Article copyright, the authors; Journal compilation copyright, J Neurol Res and Elmer Press Inc
Journal website http://www.neurores.org

Case Report

Volume 6, Number 5-6, December 2016, pages 118-123

Suspected Anterior Horn Disease Mistaken as a Mass in the Sacral Plexus: A Case Report

Figures

Figure 1.
Figure 1. Photographs of lower limbs of patient show marked muscle atrophy of posterior compartment of right calf (A) and evidence of pes cavus (B). The left plantar muscle is normal (C).
Figure 2.
Figure 2. MRI of pelvis. (A), (B), (C) are coronal and (D), (E), (F) are axial images of the pelvis. Coronal (A) and axial (D) T2-weighted images and coronal maximum intensity projection (MIP) sampling perfection with application optimized contrasts using varying flip angle evolutions (SPACE) image (B) shows a 2.2-cm diffuse nerve swelling probably representing a mass and increased signal intensity in right S1 spinal nerve as it courses out of the sacral foramen. The lesion of diffuse nerve swelling does not show enhancement on coronal (C) and axial (F) T1-gadolinium enhancement sequence. Fat-suppressed turbo-spin-echo (TSE) T1 axial image (E) shows low signal intensity along the right swelling lesion anterior to sacrum. Axial T1-weighted images (G) of the thigh shows fat replacement and atrophic change in right adductor magus, semimembranosus, and semitendinosus muscles and increased signal intensity. Axial T1-weighted image (H) of the calf shows fat replacement and atrophic change in right gastrocnemius, soleus, plantaris and posterior compartment muscles.

Tables

Table 1. Result of Nerve Conduction Study of Bilateral Lower Extremities
 
Latency (ms)Conduction velocity (m/s)Amplitude (motor, mV/sensory, μV)
RTLTNLRTLTNLRTLTNL
RT: right; LT: left; NL: normal range; NR: no response; EDB: extensor digitorum brevis; B. Fib: below fibular head; Poplit: popliteal fossa; Fib head: fibular head.
Initial
  Motor nerve
    Peroneal nerve
      EDB
        Ankle3.12.7≤ 6.57.48.8≥ 4
        B. Fib9.08.34750≥ 41.87.08.0
        Poplit10.59.44751≥ 40.06.07.8
    Tibial nerve
      Ankle8.83.2≤ 5.82.824.6≥ 5
      Knee18.99.73555≥ 40.61.923.3
    Plantar
      Medial8.43.0≤ 5.43.336.5≥ 3.5
      Lateral8.24.3≤ 6.31.819.4≥ 3.0
  Sensory nerve
    Lateral femoral cutaneous nerve2.82.5≤ 3.06158≥ 40.311.813.6≥ 2
    Peroneal nerve2.82.8≤ 4.448.050≥ 40.54838.1≥ 4.0
    Sural nerve3.43.3≤ 4.43535≥ 34.614.414.8≥ 6.0
    Plantar
      Medial2.32.910.612.1
      Lateral2.43.011.213.7
After 11 months
  Motor nerve
    Peroneal nerve
      EDB
        Ankle4.82.8≤ 6.59.210.7≥ 4
        B. Fib11.18.54853≥ 41.88.610.5
        Poplit12.49.45467≥ 40.08.510.5
    Tibial nerve
      Ankle8.83.5≤ 5.82.724.6≥ 5
      Knee18.99.93555≥ 40.61.923.3
    Plantar
      Medial8.43.0≤ 5.43.236.5≥ 3.5
      Lateral8.24.3≤ 6.31.819.4≥ 3.0
  Sensory nerve
    Lateral femoral cutaneous nerve3.13.0≤ 3.06158≥ 40.311.813.6≥ 2
    Peroneal nerve2.72.9≤ 4.45248≥ 40.59.110.8≥ 4.0
    Sural nerve3.63.2≤ 4.43538≥ 34.619.312.1≥ 6.0
    Plantar
      Medial2.42.910.212.1
      Lateral2.33.010.813.7

 

Table 2. Result of Electromyography of Bilateral Lower Extremities
 
MuscleInsertional activityFibrillationPositive sharp waveMUAPIP
RT: right; LT: left; MUAP: motor unit action potential; IP: interference pattern; NP: non-production of MUAP; RIP: reduced interference pattern; FIP: full interference pattern.
Gluteus maximus
  RTNormal--NormalFIP
  LTNormal--NormalFIP
Gluteus medius
  RTNormal--NormalFIP
  LTNormal--NormalFIP
Vastus lateralis
  RTNormal--NormalFIP
  LTNormal--NormalFIP
Biceps femoris short and long head
  RTNormal--NormalFIP
  LTNormal--NormalFIP
Semimembranosus
  RT↑+++IncreasedRIP
  LTNormal--NormalFIP
Semitendinosus
  RT↑-++NormalRIP
  LTNormal--NormalFIP
Tibialis anterior
  RTNormal--NormalFIP
  LTNormal--NormalFIP
Peroneus longus
  RTNormal--NormalFIP
  LTNormal--NormalFIP
Tibialis posterior
  RT↑+++IncreasedRIP
  LTNormal--NormalFIP
Gastrocnemius medius
  RT↑+++IncreasedRIP
  LTNormal--NormalFIP
Abductor halluces brevis
  RT↑-++NP-
  LTNormal--NormalFIP
Abductor digiti quinti pedis
  RT↑-++NP-
  LTNormal--NormalFIP
Paraspinal (C4-T1, L1-S2)
  RTNormal----
  LTNormal----