A Man With Muscle Stiffness and Later With Diplopia

A 31-year-old, right-handed man presented with left hip and low back spasms which eventually spread to all four limbs and the entire back bilaterally.

Neurologic examination showed normal mental status and cranial nerves. He had a well-developed musculature with pronounced lordosis ( Fig. 105-1 ) and had firm muscles, particularly of the lower back. There were no muscle rippling, Chvostek, Trousseau, or Babinski signs. Strength was normal. He had mildly hyperactive reflexes and normal sensation. There was no myotonia. The examination was otherwise unremarkable.

What is the Differential Diagnosis?

There are several diseases to be considered in the differential diagnosis of muscle stiffness ( Table 105-1 ). Most importantly, there was no evidence of long tract signs to suggest a myelopathy, and the stiffness was more prominent in the trunk and not focal, as in dystonia. He did not have slow relaxation of muscles to suggest hypothyroid myopathy, nor did he have clinical myotonia to suggest a myotonic syndrome, such as myotonia congenita. There was no evidence of muscle rippling to suggest rippling disease, and the stiffness was persistent and not exercise-induced, as seen in metabolic myopathies. This was present all the time, not just during relaxation after exercise, to suggest Brody disease ; also, there was no evidence of muscle fibrosis to suggest drug-induced muscle stiffness. Tetanus is another possibility, but the chronic presentation and lack of trismus are against this. Tetany might present with muscle stiffness, but such patients usually have positive Chvostek or Trousseau signs, which were not present in this patient.

Table 105-1

Differential Diagnosis of Muscle Stiffness/Spasms

Reprinted from Ahmed S, Bertorini T, Narayanaswami P, Senthilkumar K. Clinical approach to a patient presenting with muscle stiffness. J Clin Neuromuscul Dis . 2003;4(3):151.

Central

Akinetic-rigid syndromes (i.e., Parkinson disease, progressive supranuclear palsy)

Stiff-person syndrome

Progressive encephalomyelitis with rigidity

Dystonias

Tetanus

Myelopathy

Peripheral nerve

Neuromyotonia

Tetany

Benign cramps

Muscle

Hypothyroid myopathy

Myotonic syndromes

Myotonic dystrophy (DM1 and DM2)

Proximal myotonic myopathy

Myotonia congenital

Paramyotonia congenital

Schwartz–Jampel syndrome and

Metabolic myopathies (with exercise-induced spasms)

Myophosphorylase deficiency (McArdle disease)

Phosphofructokinase deficiency (Tarui disease)

Phosphorylase b kinase deficiency

Phosphoglycerate mutase deficiency

Phosphoglycerate kinase deficiency

Lactate dehydrogenase deficiency

Brody disease

Rippling muscle disease

Muscle fibrosis

Muscular dystrophies (i.e., Emery–Dreifuss type)

Drug-induced muscle fibrosis

Another possibility is neuromyotonia, or Isaacs syndrome; patients with this have stiffness with impaired relaxation, muscle aches, and cramps that are generalized and have difficulty relaxing the grip, but percussion myotonia is not frequent. Electromyographic studies show evidence of myokymia and other spontaneous discharges; the disease is caused by antibodies against voltage-gated potassium channels.

Stiff-person syndrome (SPS) is an important consideration as it manifests with marked lordosis and difficulty in relaxing muscles, as in this case. Fig. 105-2 shows the steps for the evaluation of patients with muscle spasms.

An EMG Test was Performed

Motor Nerve Studies

Nerve and Site	Latency (ms)	Amplitude (mV)	Conduction Velocity (m/s)
Ulnar Nerve R.	Normal ≤ 3.6	Normal ≥ 8	Normal ≥ 50
Wrist	2.8	11	–
Below elbow	6.7	11	54
Above elbow	8.7	10	60

Peroneal Nerve R.	Normal ≤ 5.7	Normal ≥ 3	Normal ≥ 40
Ankle	3.8	6	–
Fibular head	11.4	6	44
Knee	12.8	6	50

F-Wave and Tibial H-Reflex Studies

Nerve	Latency (ms)	Normal Latency ≤ (ms)
Ulnar nerve R.	28.8	30
Peroneal nerve R.	51.2	54
H-reflex R.	33.8	34
H-reflex L.	33.5	34

Sensory Nerve Studies

Nerve	Onset Latency (ms)	Normal Onset Latency ≤ (ms)	Peak Latency (ms)	Normal Peak Latency ≤ (ms)	Amp (μV)	Normal Amp ≥ (μV)	Conduction Velocity (m/s)	Normal Conduction Velocity ≥ (m/s)
Ulnar nerve R.	2.1	2.5	2.6	3.1	22	13	57	50
Sural nerve R.	3.2	3.5	3.7	4.0	15	11	44	40

EMG Data

Muscle	Insrt Activity	Fibs	Pos Waves	Fasc	Amp	Dur	Poly	Pattern
Deltoid R.	Norm	None	None	None	Norm	Norm	None	Full
Biceps brachii R.	Norm	None	None	None	Norm	Norm	None	Full
Triceps R.	Norm	None	None	None	Norm	Norm	None	Full
First dorsal interosseous R.	Norm	None	None	None	Norm	Norm	None	Full
Lumbar paraspinals R.	Norm	None	None	None	Norm	None	None	Full ^a
Tensor fasciae latae R.	Norm	None	None	None	Norm	Norm	None	Full ^a
Vastus lateralis R.	Norm	None	None	None	Norm	Norm	None	Full ^a
Tibialis anterior R.	Norm	None	None	None	Norm	Norm	None	Full
Vastus lateralis L.	Norm	None	None	None	Norm	Norm	None	Full
Gastrocnemius L.	Norm	None	None	None	Norm	Norm	None	Full ^a